A NEW SPECIES OF FRESHWATER CRAB (DECAPODAPOTAMONAUTIDAE)FROM THE SWAMP FORESTS OF

KWAZULU-NATAL SOUTH AFRICA BIOCHEMICAL ANDMORPHOLOGICALEVIDENCE

BY

GAVIN GOUWS13 BARBARA A STEWART1 and PATRICK E REAVELL21 Department of Zoology University of Stellenbosch Private Bag X1 Matieland 7602

South Africa2 Department of Botany University of Zululand Private Bag X1001 KwaDlangezwa 3886

South Africa

ABSTRACT

Potamonautid river crabs were collected from ve localities in northeastern KwaZulu-Natal todetermine biochemical and morphological differentiation among these populations Two distinctforms were included in these collections One of the forms could be identi ed as Potamonautessidneyi whereas the other was previously unknown Biochemical analysis of 21 presumptiveallozyme loci showed the two forms to be distinct separating at a genetic identity value of 0829 A xed allele difference at the HEX locus in the sympatric populations of the two forms indicated thatthey were reproductively isolated Morphometric analysis of seven carapace variables by means ofa discriminant function analysis showed the two forms to be distinct The unidenti ed form whichappears to be con ned to patches of swamp forest in northeastern KwaZulu-Natal is described inthis paper as Potamonautes lividus sp nov

REacuteSUMEacute

Des crabes de riviegravere du genre Potamonautes ont eacuteteacute reacutecolteacutes dans cinq localiteacutes de la reacutegionnord-orientaledu KwaZulu-Natal a n de deacuteterminer les diffeacuterences biochimiqueset morphologiquesentre les diffeacuterentes populations Deux formes distinctes eacutetaient preacutesentes dans ces reacutecoltes Lrsquounede ces formes a pu ecirctre identi eacutee comme Potamonautes sidneyi tandis que lrsquoautre eacutetait inconnuejusqursquoagrave preacutesent Lrsquoanalysebiochimiquede 21 loci enzymatiquesa montreacute que les deux formes eacutetaientdistinctes seacutepareacutees par une valeur drsquoidentiteacute geacuteneacutetique de 0829 Une diffeacuterence alleacutelique xe aulocus HEX dans les populations sympatriques des deux formes indique qursquoils sont isoleacutes du point devue reproductifLrsquoanalyse morphomeacutetrique de sept variables de la carapace au moyen drsquoune analysediscriminante a montreacute que les deux formes eacutetaient distinctes La forme non-identieacutee qui apparaicirctcon neacutee agrave des pans de forecirct mareacutecageuse au nord-est du KwaZulu-Natal est deacutecrite dans ce travailcomme Potamonautes lividus sp nov

3 e-mail ggouwslandsunacza

cdeg Koninklijke Brill NV Leiden 2001 Crustaceana 74 (2) 137-160

138 G GOUWS B A STEWART amp P E REAVELL

INTRODUCTION

Freshwater crabs of the family Potamonautidae Bott 1970 are common through-out the rivers of KwaZulu-Natal South Africa Of the three species documentedfrom the province (Barnard 1935 1950) two Potamonautes sidneyi Rathbun1904 and Potamonautes dentatus Stewart Coke amp Cook 1995 are known to occurfrom the low-lying midlands to the coast

The earliest records of Potamonautes sidneyi from the rivers of the province dateback to 1910 Stebbing (1910) documented collections made at Port Natal Lenz(1912) referred to collections made at Lake Sibayi and elsewhere in Zululandand Barnard (1935) reported collections in the Transvaal Museum made atOliviershoek in the northern Drakensberg Potamonautes dentatus however hasonly recently been described from the Mgeni River Inyamvubu River and othertributaries of the Tugela River (Stewart et al 1995)

Collections made near Empangeni and Richards Bay revealed specimens thatcould not be identi ed as any of the species known from the province of KwaZulu-Natal The specimens were characterized by having a highly vaulted carapacea medially reduced postfrontal crest in ated arched chelipeds a downwardprojecting frontal lobe rounded downward sloping epibranchial corners anda characteristic silver-blue carapace sheen and bright orange to red chelipedsand pereopods The specimens appear to exclusively inhabit small patches ofswamp forest and associated herbaceous wetland with characteristic swamp forestvegetation assemblages (Wessels 1997) and spongy peat-soil in which thesecrabs form shallow U-shaped burrows partly lled with water The uniquemorphological characteristics and habitat requirements of this form raised thequestion whether it could be delineated as a species separate to those previouslyknown from the province

This paper provides empirical morphological and biochemical evidence for anew species of potamonautid river crab from the swamp forests of northeasternKwaZulu-Natal described as Potamonautes lividus sp nov Results are discussedagainst the broader evidence of variation and differentiation within the genusPotamonautes and the putative new species is compared to species known fromSouth Africa and further a eld

MATERIALS AND METHODS

Collection mdash Crabs were collected from ve localities ( g 1) using handnetsbaited with ox-heart Individuals of the undescribed form (form A) were easilyidenti able in the eld due to the much in ated carapace downward projecting

POTAMONAUTES LIVIDUS NOV 139

Fig 1 Sampling localities in northeasternKwaZulu-Natal South Africa

140 G GOUWS B A STEWART amp P E REAVELL

frontal lobe and characteristic colouration Potamonautes sidneyi (form B) indi-viduals could be identi ed following the descriptions and illustrations of Barnard(1950) and Bott (1955) by the presence of a sharp postfrontal crest scabrosityof the epibranchial corners and broad limbs Individuals of the undescribed form(form A) were collected from a patch of swamp-forest dominated by Syzygiumcordatum Hochst (common waterberry) trees and characterized by spongy hy-dromorphic peat soil at the University of Zululand campus a similar forest alongthe Mdibi stream (an af uent of Lake Mzingazi) north of Richards Bay and aFicus trichopoda Bak and Barringtonia racemosa (L) Roxb dominated swamp-forest near the Mapelane Nature Reserve Populations of P sidneyi were sampledfrom marshy grassland near Dakaneni village outside Hluhluwe Game Reserveand the upper reaches of the Manzibomvu River within the Hluhluwe Game Re-serve Potamonautes sidneyi populations were also sampled from the University ofZululand campus and Mdibi swamp-forest where they occur sympatrically withthe undescribed form (form A) Crabs were killed by overnight freezing Unfor-tunately specimens of P sidneyi from the Mdibi swamp-forest were unsuitablefor genetic analysis as specimens were processed days after capture and proteindenaturation could not be avoided due to repeated freezing and thawing duringtransportation

Biochemical analysis mdash Muscle and digestive-gland tissue (hepatopancreas)were removed from each specimen by dissection Tissue samples were stored incryogenic tubes at iexcl80plusmnC until electrophoresis was ready to be performed Tissuewas homogenized in 001 M Tris buffer (pH 8) using a glass rod attached to avariable-speed electric motor The samples were centrifuged for ve minutes at12000 rpm prior to use Filter paper wicks (Whatmans 3) were dipped into thesupernatant and inserted into the horizontal 13 starch gel (Sigma Chemicals CoSt Louis Missouri USA)

Three electrophoretic buffer systems were used (A) a discontinuous Tris-citrate-borate-lithium hydroxide buffer with a gel buffer pH 87 and an electrodebuffer pH 80 (Ridgeway Sherburne amp Lewis 1970) (B) a continuous Tris-borate-EDTA buffer system at pH 86 (Markert amp Faulhaber 1965) and (C) a continuousTris-citrate buffer system at pH 69 (Whitt 1970) Gels were run inside a fridge(4plusmnC) for 4 hours at 40 mA These were then sliced horizontally into 3 or 4 slicesand the sites of enzymatic activity histochemically stained in a 2 agar overlay(Shaw amp Prasad 1970)

Of 24 isozyme loci originally screened 21 were reliably interpretable andincluded in the analyses (table I) A sample of Potamonautes depressus Krauss1843 from the Coleford Nature Reserve was included in each run as a referencepopulation to provide continuity in scoring across all populations For each locusthe most common allele of the Coleford population was assigned a value of 100

POTAMONAUTES LIVIDUS NOV 141

TABLE IEnzymes and buffer systems used to determine biochemical variation in six populations of Potamo-

nautes spp studied

Enzyme Abbreviation EC Number Buffer Tissue Loci

Arginine kinase ARK 2733 A m 1Diaphorase DIA 1622 A h 1Glucose-6-phosphateisomerase GPI 5319 A m 1Hexokinase HEX 2711 B m 1Isocitrate dehydrogenase IDH 11142 C m 2Lactate dehydrogenase LDH 11127 A m 1Malate dehydrogenase MDH 11137 C m 2Malic enzyme ME 11140 B m 1Mannose-phosphate isomerace MPI 5318 B m 1Peptidase (glycyl-leucine as substrate) GL 3411ndash B m 1Peptidase (leucyl-glycyl-glycylas substrate) LGG 3411ndash A h 3Peptidase (leucyl-tyrosineas substrate) LT 3411ndash A B m h 2Peptidase (phenylamine-prolineas substrate) PHP 3411ndash B h 1Phosphoglucomutase PGM 5422 B m 2Phosphoglusonatedehydrogenase PGD 11144 C m 1

Buffer (A) discontinuous Tris-citrate-borate-lithium hydroxide buffer system (Ridgeway et al1970) (B) continuous Tris-borate-EDTA buffer system (Markert amp Faulhaber 1965) and (C) con-tinuous Tris-citrate buffer system (Whitt 1970) Tissue (m) muscle tissue and (h) hepatopancreas (digestive gland)

and all other alleles were scored relative to this value Where more than one locusstained for a particular enzyme the most anodally migrating one was labeled 1and the others labeled sequentially

All numerical analyses were performed using the BIOSYS-1 program (Swof-ford amp Selander 1981) Allele and genotype frequencies were calculated Geno-type frequencies were tested for deviation from frequencies expected under Hardy-Weinberg equilibrium by means of a Acirc2-goodness-of- t test Where more than twoalleles occurred at a locus the genotype frequencies were pooled Percentage poly-morphic loci were calculated for each population using no criterion (loci wereconsidered polymorphic if more than one allele was present at a locus) The meanexpected heterozygosity (H) was also calculated for each locus using unbiasedestimates (Nei 1978) The mean unbiased genetic identity (I ) and distance (D)were calculated for each pairwise comparison (Nei 1978) and a dendrogram con-structed using the measures of genetic identity and the UPGMA clustering algo-rithm (Sneath amp Sokal 1973)

Morphological analyses mdash Prior to dissection crabs were sexed and measuredusing digital Vernier-calipers and a portable computer The populations used forthe genetic analysis were supplemented with morphometric data from specimens

142 G GOUWS B A STEWART amp P E REAVELL

collected earlier at the above localities Seven carapace variables were recorded formorphometric analyses These were carapace length along the medial line (CL)carapace width at the widest part (CWW) posterior carapace width (CWP) thedistance between the postfrontal crest and the anterior carapace margin (PFCD)distance between the medial margins of the orbits (ED) distance between theexorbital teeth (CWA) and the carapace height (CH)

Data were log transformed (common logarithms) prior to analysis All statisticalanalyses were performed using the Statistica Version 51 program (StatSoft Inc1996) Morphological variation between the two forms was determined by meansof a stepwise discriminant function analysis using seven carapace variablesClassi cation functions were calculated using the jackknife procedure ensuringan unbiased classi cation function for determining group assignment Individualswere then reassigned to a group based on the highest a posteriori probability Afrequency histogram of individual canonical variable scores calculated from thediscriminant function analysis was plotted to reveal discrimination between thetwo forms Linear regression analyses were used to test for variation within speci cvariables between the two forms

Gonopods and mouthparts were removed and examined qualitatively using aLeitz stereoscopic dissection microscope and illustrated using a camera lucida orphotographed using a Wild MPS45 camera unit

RESULTS

Biochemical analysis mdash Of the 21 reliably scorable loci nine (ARK LT-1ME LDH MPI PGD DIA LGG-1 and LGG-3) were monomorphic across allpopulations analysed Twelve loci were polymorphic (table II) The LT-2 locus wasthe only locus polymorphic in each population The total number of alleles rangedfrom two in HEX MDH-1 IDH-1 GL PGM-2 PHP-2 and LGG-2 to ve in GPIWithin populations the maximum number of alleles was four found in GPI in theManzibomvu population

Out of thirty cases of polymorphism for all enzyme loci and populations three(10) were shown to deviate from genotype frequencies expected under Hardy-Weinberg equilibrium The LT-2 locus in the University of Zululand A population(Acirc2 D 9468 df D 3 P D 0024) the PHP locus in the Mdibi population(Acirc2 D 7037 df D 1 P D 0008) and the PGM-2 locus in the Dakanenipopulation (Acirc2 D 250 df D 1 P D 0000) were out of equilibrium due toa de cit of heterozygotes carrying the rare allele All other loci conformed toHardy-Weinberg expectations thus supporting a purely genetic interpretation ofthe polymorphisms observed

POTAMONAUTES LIVIDUS NOV 143

TABLE IIDistribution of allele frequencies at nine polymorphic loci in six populations of Potamonautes spp

studied N D sample size refer to table I for enzyme abbreviations

Population

Locus Zululand A Mdibi Mapelane Zululand B Dakaneni Manzibomvu

IDH-2N 41 24 25 13 25 13120 0012 0729 0380 0000 0000 000080 0988 0229 0000 1000 1000 100045 0000 0043 0620 0000 0000 0000

GPIN 56 26 25 13 25 13165 0045 0000 0000 0000 0000 0000150 0000 0000 0000 0000 0000 0038100 0000 0000 0000 0000 0000 003840 0938 1000 1000 0962 0880 0846

iexcl80 0018 0000 0000 0038 0120 0077

HEXN 41 26 25 13 25 13100 1000 1000 1000 0000 0000 000095 0000 0000 0000 1000 1000 1000

MDH-1N 41 26 25 13 25 13100 0988 1000 1000 1000 1000 100090 0012 0000 0000 0000 0000 0000

MDH-2N 41 26 25 13 25 13100 1000 1000 1000 0962 0960 100075 0000 0000 0000 0000 0040 000065 0000 0000 0000 0038 0000 0000

IDH-1N 41 26 25 13 23 7150 0000 0000 0000 1000 0891 0929135 1000 1000 1000 0000 0109 0071

LT-2N 41 26 25 13 25 13250 0049 0019 0020 0000 0000 0000100 0854 0885 0840 0923 0980 0769

0 0098 0096 0140 0077 0020 0231

PGM-1N 52 26 25 13 25 13110 0365 0000 0000 0000 0000 0000100 0212 0000 0000 0038 0140 003890 0423 1000 1000 0923 0800 096275 0000 0000 0000 0038 0060 0000

(continued overleaf)

144 G GOUWS B A STEWART amp P E REAVELL

TABLE II(Continued)

Population

Locus Zululand A Mdibi Mapelane Zululand B Dakaneni Manzibomvu

GLN 41 26 25 13 25 1390 1000 0962 1000 1000 1000 100075 0000 0038 0000 0000 0000 0000

PGM-2N 56 26 25 13 25 13100 1000 1000 1000 0000 0040 000075 0000 0000 0000 1000 0960 1000

PHPN 41 26 25 13 25 13105 1000 0808 1000 1000 1000 100090 0000 0192 0000 0000 0000 0000

LGG-2N 41 26 25 13 24 13100 0854 0942 1000 0846 0979 069290 0146 0058 0000 0154 0021 0308

Genetic variability was low in all populations The percentage polymorphicloci (no criterion) ranged from 95 to 333 in the Mapelane and Dakanenipopulations respectively The mean unbiased expected heterozygosity varied from0034 (in the University of Zululand B population) to 0063 (in the Universityof Zululand A and Manzibomvu populations) The mean number of alleles perlocus ranged from 11 (in the Mapelane population) to 14 (in the Dakaneni andUniversity of Zululand A populations)

The dendrogram constructed based on the genetic identity values obtained bypairwise comparison of populations (table III) clearly distinguished two clusters( g 2) The group representing the form A populations clearly separated from thegroup representing the form B (Potamonautes sidneyi) populations at a geneticidentity value of I D 0829 D D 0187 Three loci contributed signi cantly tothis separation one of them diagnostically The HEX locus showed a xed alleledifference between the individuals of the two forms with the form A individualsbeing xed for the allele HEX100 and the form B (P sidneyi) individuals xed forthe HEX95 allele Strong heterogeneity was observed between the populations ofthe two forms at the IDH-1 and PGM-2 loci With the exception of one individualin the Dakaneni population having a homozygote with the PGM-2100 allele form Aand form B were characterized by the xation of alleles PGM-2100 and PGM-275

POTAMONAUTES LIVIDUS NOV 145

TABLE IIICoef cient matrix of Neirsquos (1978) unbiased genetic identity (above diagonal) and unbiased geneticdistance (below diagonal) for pairwise comparisons of the six populations of Potamonautes studied

Population

Zululand A Mdibi Mapelane Zululand B Dakaneni Manzibomvu

Zululand A currencurrencurrencurrencurren 0958 0949 0840 0855 0842

Mdibi 0043 currencurrencurrencurrencurren 0986 0821 0832 0822

Mapelane 0052 0014 currencurrencurrencurrencurren 0813 0825 0814

Zululand B 0174 0197 0206 currencurrencurrencurrencurren 0998 0999

Dakaneni 0157 0184 0193 0002 currencurrencurrencurrencurren 0994

Manzibomvu 0172 0196 0206 0001 0006 currencurrencurrencurrencurren

Fig 2 UPGMA dendrogram constructed from the matrix of Neirsquos (1978) unbiased genetic identi-ties (I ) using allozyme data from 21 loci

respectively Identity-values for within form comparisons varied from 0949 to0986 (D D 0014 to 0052) and 0994 to 0999 (D D 0001 to 0006) for form Aand form B respectively

Morphometric analysis mdash Individuals from the form A populations couldeasily be distinguished from the form B (P sidneyi) individuals by the possessionof a much more vaulted carapace in ated chelipeds a postfrontal crest whichdiminishes medially and the characteristic silver-blue carapace sheen and brightorange to red chelipeds and pereopods Mature form B (P sidneyi) individualsfrequently attained a larger size class (with CL being representative of size) thandid the mature form A individuals

146 G GOUWS B A STEWART amp P E REAVELL

Three carapace variables (ED CH and CWP) contributed signi cantly to thediscrimination between the two forms in the discriminant function analysis Thehistogram plot of observed canonical variable scores ( g 3) clearly separates thetwo forms with the canonical variable means of the form A and form B individualscalculated at iexcl0996 and 1965 respectively The classi cation function (the linearfunction of variables which best discriminates the individuals of one group fromthe other speci ed groupings) was calculated for individuals of each form Theclassi cation function of the form A group was

Y D 306704 (Log CWP) iexcl 26103 (Log ED) iexcl 228513 (Log CH) iexcl 64156

and of the form B (P sidneyi) group

Y D 35097 (Log ED) iexcl 315543 (Log CH) C 347231 (Log CWP) iexcl 88367

Using the classi cation functions individuals were reassigned to groups basedon highest a posteriori probabilities Of the form A individuals 9437 (134of 142) were correctly classi ed with eight individuals being reassigned to theform B group Of the form B individuals 8889 were correctly reassigned to theP sidneyi group with eight of the 72 individuals being reassigned to the form Agroup

Fig 3 Histogram of scores for specimens of Potamonautes lividus sp nov (form A) and P sidneyiRathbun 1904 (form B) along the canonical variable calculated from a discriminant function

analysis using seven carapace variables

POTAMONAUTES LIVIDUS NOV 147

Comparison of regressions of the most discriminating variables between the twoforms regressed over CL in turn also showed signi cant differences between thetwo forms CH regressed over CL showed highly signi cant differences betweenthe two forms (SS D 0011 df D 1 F D 31266 P lt 0001) as did ED(SS D 0011 df D 1 F D 8333 P lt 0005) and CWP (SS D 0006 df D 1F D 8136 P lt 0005) These represent the most discriminating variables andtheir regressions are represented graphically ( g 4a b c) PFCD (SS D 0199df D 1 F D 52671 P lt 0001) CWW (SS D 0003 df D 1 F D 30963P lt 0001) and CWA (SS D 0001 df D 1 F D 6182 P lt 002) also showedthat there were signi cant differences between the two forms but the discriminantfunction analysis showed them to be redundant in constructing the model

Qualitative analysis mdash Examination of gonopods and mouthparts revealed onlyslight differences in gonopod morphology The terminal segment of gonopod 1of the undescribed form was relatively short and triangular whereas the terminalsegment of gonopod 1 of P sidneyi appears to be substantially longer and moreslender Although the terminal segment is bent away from the medial line in bothforms the terminal segment in P sidneyi possesses a lobe or ange that extendsinwards giving the terminal segment an S-shaped appearance The gonopods andmandibular palps of the two forms are illustrated in g 5

DISCUSSION

The data presented above clearly indicate that the two forms of freshwatercrabs from KwaZulu-Natal are distinct The form A specimens are smaller with amore vaulted carapace that is relatively narrower posteriorly and that possessesa relatively narrower frontal lobe (ED) than that of the Potamonautes sidneyiindividuals

Not only are the two forms clearly distinct both biochemically and morpho-logically but strong evidence suggests that they are reproductively isolated Thepresence of a diagnostic locus HEX xed for alternate alleles in the sympatricpopulation of the two forms indicates that a lack of gene ow and thus repro-ductive isolation exist between the two forms This allows for species recognitionunder the Biological Species Concept (Mayr 1970) under which species are de- ned as ldquogroups of actually or potentially interbreeding populations which arereproductively isolated from other such groupsrdquo (Mayr 1963 19) or ldquogeneticallyisolated (in nature) from other such groupsrdquo (Bock 1986 33) In his model of al-lopatric speciation Bock (1986) suggested that newly evolved species in sympatrywould exert mutually selective demands on each other by means of reproductive

148 G GOUWS B A STEWART amp P E REAVELL

Fig 4 Comparisons of the regressions of (A) Log CH (carapace height) over Log CL (carapacelength) (B) Log ED (eye distance) over Log CL and (C) Log CWP (posterior carapace width) overLog CL between form A (Potamonautes lividus sp nov) and form B (P sidneyi Rathbun 1904) All

differences are signi cant (at the P lt 0005 level)

POTAMONAUTES LIVIDUS NOV 149

Fig 5 A-E form A (Potamonautes lividus sp nov composite of male holotype SAM A43540and unaccessioned material) A carapace outline B left mandibular palp anterior view C leftmandibular palp posterior view D left gonopod 1 anterior view and E left gonopod 1 posteriorview F-J form B (Potamonautes sidneyi Rathbun 1904 unaccessioned specimen) F carapaceoutline G left mandibular palp anterior view H left mandibular palp posterior view I left

gonopod 1 anterior view J left gonopod 1 posterior view

150 G GOUWS B A STEWART amp P E REAVELL

interference and ecological competition This would lead to a divergence of mor-phological and behavioural aspects of feeding reproduction and other ecologicalfeatures The different gonopod morphologies of the two forms may re ect this

The three form A populations clustered separately from the three P sidneyipopulations at a I -value of 0829 Stewart (1997a) calculated the separationI -value between P parvispina Stewart 1997 and P perlatus H Milne Edwards1837 to be 068 An I -value of 066 separated both P perlatus and P brinckiBott 1960 in the Western Cape (Stewart 1997b) and P unispinus Stewart ampCook 1998 and P sidneyi in Mpumalanga (Stewart amp Cook 1998) An I -valueof 0599 was obtained separating P clarus Gouws Stewart amp Coke 2000 andP depressus (Gouws et al 2000) The only species in the genus delineated using ahigher I -value was P granularis Daniels Stewart amp Gibbons 1998 which wasseparated from P perlatus in the Olifants River at a I -value of 088 (Danielset al 1998a 1999) Although slightly higher than most interspeci c values inthe genus the value obtained in this study nevertheless falls within the range (035to 085) speci ed by Thorpe (1982) to indicate congeneric species differencesAllopatric populations showing I -values of less than 085 are unlikely to beconspeci c (Thorpe amp Soleacute-Cava 1994) With the exception of two cases allpairwise comparisons between allopatric populations of the two forms yieldedI -values less than 085

Identity-values were high for comparisons within both the form A (0949 to0986) and P sidneyi (0994 to 0999) groups Intraspeci c I -values are generallyhigh in the genus Potamonautes and disjunct populations within a species tendto be genetically undifferentiated Intraspeci c I -values obtained in six studies(Stewart 1997a b Stewart amp Cook 1998 Daniels et al 1998b 1999) involvingsix Potamonautes species varied from 0902 to 1000 (D D 0000 to 0103)An intraspeci c I -value of 075 was obtained in a comparison of two groups ofP brincki populations across the Cape Peninsula and Cape Flats However thismost probably indicates a species difference and requires further investigation(Stewart 1997b) Given the high intraspeci c I -values characteristic of the genusand those obtained for comparisons within each form the I -value obtainedfor the comparison between the two forms most likely represents a speciesdifference

Bock (1986) also de ned a species as possessing a set of three distinctcharacteristics genetic unity reproductive unity and ecological unity Biochemicaldata provide support for compliance with the rst two criteria for both formsWhile no empirical evidence is as yet available con rming the third factor adegree of macro- and microhabitat segregation and thus ecological segregationis evident between the two forms Potamonautes sidneyi is widespread acrossthe province (Stewart et al 1995) while the other form appears to have a

POTAMONAUTES LIVIDUS NOV 151

more limited distribution in northeastern KwaZulu-Natal restricted to patches ofswamp forest with particular oral assemblages The swamp forests are oftencharacterized by Barringtonia racemosa Syzygium cordatum Ficus trichopodaHibiscus tiliaceus L Rauvola caffra Sond Voacanga thouarsii Roem amp SchultRaphia australis Oberm amp Strey and Podocarpus falcatus (Thunb) R Br exMirb with the fern Stenochlaena tenuifolia (Desv) T Moore often present in theunderstorey (Bruton 1980 Moll 1980) Within the swamp forests the sympatricpopulations appear to show a degree of microhabitat segregation Observationssuggest that P sidneyi has a closer association with water as individuals were nevercollected great distances away from seepage pools and channels owing throughthe forest Conversely individuals of the swamp-forest form were most oftencollected farther from water and their burrows were often among the vegetationObservations suggest that this form is more terrestrial Individuals were noticedto move to higher elevations when the water table rose through the hydromorphicpeat soil ooding their burrows and the surface and they were also more active oncloudy overcast days Evidence of terrestrial adaptation is most likely to be foundin the structure and histology of the organs and tissues involved in respirationfactors such as branchial chamber shape and volume gill structure and formulaand the structure and vascularization of the branchiostegite lining are knownto re ect changes brought upon by the constraints of the terrestrial environment(Greenaway amp Taylor 1976 Diacuteaz amp Rodriacuteguez 1977 Taylor amp Greenaway1979 Cumberlidge 1986 1991 Takeda et al 1996) Although the availabilityof material prohibited the investigation of this aspect future research may prove tobe fruitful and highlight a greater distinction between the two forms

Studies on terrestrial adaptation supplemented by behavioural data that couldillustrate microhabitat and ecological segregation would quantify further thedegree of differentiation between the two forms However two independent datasets biochemical and morphological present strong evidence for the speci c statusof the swamp-forest form

TAXONOMY

Potamonautes lividus sp nov ( gs 6-7)

Material examined mdash Holotype South African Museum (SAM) A43540 one male CL D255 mm Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws andL Hoenson Allotype SAM A43541 one female CL D 245 mm Ficus and Barringtonia swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S 32plusmn2401800E)coll 27 January 1997 by B A Stewart G Gouws and L Hoenson Other material SAM A43542two males Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws

152 G GOUWS B A STEWART amp P E REAVELL

and L Hoenson SAM A43543 one female Lake Nhlabane north of Richards Bay (28plusmn3800500S32plusmn1601700E) coll 27 April 1993 by the University of Zululand Zoology Department SAMA43544 three males one female Mdibi swamp forest along Mdibi stream 8 km north of RichardsBay (28plusmn4202400S 32plusmn0902600E) coll 26 January 1997 by B A Stewart P A Cook M CokeP E Reavell G Gouws and L Hoenson SAM A43545 one male one female Syzygium forestUniversity of Zululand campus (28plusmn5102500S 31plusmn5100200E) coll 24 January 1997 by B A StewartP A Cook P E Reavell G Gouws and L Hoenson SAM A43546 two males two femalesUniversity of Zululand stream owing through campus (28plusmn550S 31plusmn410E) coll 10 September 1995by P E Reavell SAM A41313 one male one female swamp forest Empangeni (28plusmn5102500S31plusmn5100200E) coll 2 August 1994 by M Coke SAM A41155 one male University of ZululandSyzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S 31plusmn450E) coll 10 December1988 by P E Reavell SAM A41153 three males smaller holes in hydromorphic soil Syzygiumcordatum swamp forest University of Zululand (28plusmn450S 31plusmn450E) coll 20 March 1994 byP E Reavell SAM A41156 one female Syzygium cordatum swamp forest University of Zululand(28plusmn450S 31plusmn450E) coll 18 May 1992 by P E Reavell SAM A41154 one male one femaleUniversity of Zululand Syzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S31plusmn450E) coll 10 May 1990 by P E Reavell SAM A43547 two males one female swamp forestUniversity of Zululand (28plusmn450S 31plusmn450E) coll 1 April 1994 by P E Reavell SAM A43548one male one female Syzygium and Bridelia dominated swamp forest University of Zululand(28plusmn5102500S 31plusmn5100200E) coll 7 October 1996 by P E Reavell SAM A43549 one female Mdibiswamp forest Lake Msingazi catchment area north of Richards Bay (28plusmn420S 32plusmn090E) coll5 December 1996 by P E Reavell Albany Museum mdash GEN910 one female Mpolozi swampsMapelane (28plusmn2601300S 32plusmn2402500E) coll 13 February 1991 Albany Museum mdash GEN965 twomales ve females NrsquoKoninga Valley Richards Bay (28plusmn450S 32plusmn030E) coll 7 April 1988

Other material mdash The following specimens included in the collections of the South AfricanMuseum warrant further investigation as although they bear some resemblance to the speciesdescribed below their identi cation is uncertain SAM A41276 one male one female Mbonenidam Mkuze Game Reserve (27plusmn3705700S 32plusmn1504500E) coll 28 October 1994 by M Coke SAMA41299 two males Nxwala stream Mkuze Game Reserve (27plusmn4302300S 32plusmn1601000E) coll 10November 1994 by O Bourquin SAM A41277 one male Rainpool south of entrance False BayPark (28plusmn0000100S 32plusmn2102100E) coll 26 October 1994 by M Coke SAM A41300 two malesKangela rainpoolN2 near Mtubatuba (28plusmn2200000S 32plusmn1103600E) coll 25 October 1994 by M Cokeand SAM A41211 one male Ntambanana (Ntrabanana) Zululand coll by H H Curson

Type locality mdash South Africa KwaZulu-Natal Barringtonia and Ficus swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S32plusmn2401800E)

Distribution mdash At present known only from the swamp forests (characterizedby Barringtonia racemosa Syzygium cordatum and Ficus trichopoda vegetationand spongy hydromorphic peat-soil) in the vicinity of Richards Bay Empangeniand the Mapelane Nature Reserve It is probable that the distribution of the speciesmay extend into low-lying areas to the east of the Drakensberg escarpment in theprovince of Mpumalanga and into Mozambique

Etymology mdash From the Latin ldquolividusrdquo meaning ldquobluerdquo or ldquolight bluerdquoreferring to the characteristic silver-blue sheen of the carapace The epitheton isan adjective agreeing in gender with the (masculine) generic name

POTAMONAUTES LIVIDUS NOV 153

Fig 6 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A wholeanimal dorsal aspect B whole animal ventral aspect C cephalothorax frontal aspect

Diagnosis mdash Carapace distinctly vaulted and relatively narrow posteriorlyEpibranchial teeth absent and anterolateral margin of the carapace smooth Post-frontal crest indistinct medially with frontal lobe projecting downwards Cara-pace characteristically orange to red with silver-blue sheen Chelipeds and limbs

154 G GOUWS B A STEWART amp P E REAVELL

bright orange to red with lighter cheliped and dactyl tips Chela in ated and highlyarched

Description of male holotype mdash Size Measurements of the holotype and theranges of other specimens are given in table IV

Carapace ( gs 6A C 7A) Carapace and limbs characteristically orange tored with the carapace possessing a silver-blue sheen when alive Preserved spec-imens (70 ethanol) appear less orange and the carapace retains a blue-greycolour Cephalothorax ovoid distinctly vaulted branchial region highly convex( g 6A C) maximum height and width at anterior third (ratio CHCL D 065CWWCL D 145) Anterior margin straight Urogastric grooves moderately wellde ned Cardiac grooves shallow and poorly de ned Carapace otherwise smoothPostfrontal crest smooth curves forward medially Postfrontal crest diminishesabove inner orbit margins though well de ned immediately lateral to forked mid-point groove by means of two indentations anterior to crest indicating epigas-tric lobes Exorbital teeth moderately sharp but small Epibranchial teeth ab-sent Anterolateral margin posterior to postfrontal crest smooth margin curvingin over carapace in branchial region though indistinctly Each ank has a longitu-dinal groove dividing the subhepatic from the pterygostomial region with verticalgroove running from longitudinal groove joining anterolateral margin between ex-orbital tooth and postfrontal crest

Sternites ( gs 6B 7B) Sternites 1 and 2 fused no suture visible First suture(sternal groove) between sternites 2 and 3 complete Second sternal groove

TABLE IVPotamonautes lividus sp nov wet weight (in g) and measurements (in mm) for the male holotype

and ranges for other individuals examined (maximum of 77 males and 70 females)

Variable Abbreviation Holotype Males Females

Wet weight WW 242 05-214 07-183Carapace length CL 255 84-247 89-276Carapace widest width CWW 370 114-360 118-373Carapace posterior width CWP 281 90-269 86-306Distance between postfrontal crest

and anterior margin PFCD 43 12-222 15-46Distance between orbits ED 114 42-119 43-123Distance between exorbital teeth CWA 259 96-254 96-262Carapace height CH 165 48-171 50-162Width of sixth abdominal segment AW6 75 28-74 31-240Major cheliped propodus length MCPL 427 71-402 76-291Major cheliped propodus height MCPH 198 28-189 28-142Pereopod 2 merus length P2ML 189 50-181 51-171Pereopod 2 merus width P2MW 58 19-56 18-59

POTAMONAUTES LIVIDUS NOV 155

Fig 7 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A carapaceoutline B thoracic sternum C right cheliped dactylus and propodus D left cheliped dactylusand propodus E left third maxilliped F left mandible and mandibular palp posterior view G leftmandibular palp posterior view H left mandibular palp anterior view I left gonopod 1 anteriorview J terminal segment left gonopod 1 anterior view K left gonopod 1 posterior view L leftgonopod 2 anterior view Scale lines represent 1 mm except for A-D where they represent 10 mm

156 G GOUWS B A STEWART amp P E REAVELL

between sternites 3 and 4 complete laterally becoming shallower mediallysloping sharply towards abdominopelvic region

Third maxillipeds ( gs 6C 7E) Filling entire buccal frame except for ovalefferent respiratory openings short agellum present on exopods ischium smoothwith moderately deep vertical groove

Mandibular palp ( g 7F G H) Mandibular palp with two segments terminalsegment undivided with a dense tuft of setae on posterior surface of angeof terminal segment Margins generally hirsute Subterminal segment slightlyenlarged distally

Chelipeds and walking legs ( gs 6A 7C D) Chelipeds markedly unequaldactylus of right cheliped strongly arched 163 times length of dactylus of leftcheliped Both dactyli armed with up to 20 cutting teeth three to four of whichare slightly larger and more prominent Propodus of right cheliped markedlyin ated 168 times longer and 20 times wider than that of left cheliped Pollexpossesses 20 cutting teeth four to ve of which are more prominent Carpi ofboth chelipeds possess one prominent and three rudimentary teeth Margins ofmeri granulose small blunt spine on anterior surface no spine on anterior-inferiormargin Pereopods generally slender (pereopod 2 merus length width D 328 andpereopod 5 merus lengthwidth D 271) P3 longest P5 shortest ventral marginsof propodi and meri smooth dorsal margin with ne sharp bristles dactyli endingin sharp points with margins bearing a series of sharp spinelike bristles

Pleon ( gs 6B 7B) First ve segments broad and short last two segmentslonger terminal segment rounded at distal end

Pleopods ( g 7I J K) Pleopod 1 (gonopod 1) terminal segment short 025times length of subterminal segment terminal segment curves away from mid-line when viewed posteriorly widest at base ending in pointed tip Subterminalsegment of pleopod 1 tapers distally inner lateral margin slightly irregular outerlateral margin straighter both margins hirsute Posterior surface with twisting lon-gitudinal groove extending length of subterminal and terminal segment Groovenot visible on anterior surface Posterior surface and margins of groove hirsutePleopod 2 (gonopod 2) terminal segment lament-like 05 the length of subter-minal segment curving slightly towards medial line proximally curves away frommedial line distally ( g 7L) Subterminal segment widest at base tapering sharplyinwards at 04 of length forms narrow process supporting terminal segment

Variation mdash All individuals are characteristically dark orange to red witha silver-blue sheen to the carapace while the chelipeds vary in colour frombright orange-red to a lighter yellow-orange All individuals are characterized byhighly vaulted carapaces and downwardly projecting frontal lobes The postfrontalcrest which is most pronounced laterally (from directly above the orbits to theanterolateral margin) and incomplete medially is often more distinct in the smaller

POTAMONAUTES LIVIDUS NOV 157

individuals Chelipeds are not always typically arched enclosing a large ovoidspace as in the holotype Chelipeds of smaller individuals although in ated areless arched and often tight closing with the small cutting teeth more obviousChelipeds of females and small males in particular from the Mdibi and Universityof Zululand localities have propodi that are relatively high with in ated palmsand relatively short tightly closing chelae which project slightly downwardsHeterochely has been demonstrated in most Potamonautes-species occurring inSouth Africa (Siegfried 1972 Raubenheimer 1986 Stewart et al 1995 Stewart1997a b Stewart amp Cook 1998 Daniels et al 1998a Gouws et al 2000) Withinthe species 76 of the specimens were right-handed with 11 being left-handedand 13 being of equal or subequal (differing by less than one millimeter) sizeOf the males 79 were right-handed 8 left-handed and 13 equal or subequalFemales had 74 right-handedness 13 left-handedness and in 13 of caseschelipeds were equal or subequal The abdomen of mature females completelyoverlaps the coxae of the pereopods The smallest mature female had a CL of167 mm with the largest immature female having a CL of 159 indicating that thepubertal moult occurs approximately between the 14 mm and 18 mm size classes

Remarks mdash Potamonautes lividus sp nov can readily be distinguished from theten other species in the genus Potamonautes known to occur within South AfricaPotamonautes warreni Calman 1918 P dentatus P parvispina and P unispinusall bear a singular spine or a series of teeth on the anterolateral margins whereasP lividus sp nov is smooth Potamonautes perlatus P sidneyi and P granularisare all larger crabs with in ated arched carapaces with complete distinct post-frontal crests and scabrosity or granulation of the anterior margins orbits epi-branchial corners or postfrontal crests Potamonautes lividus sp nov has smoothcarapace margins and a incomplete postfrontal crest The terminal segment ofgonopod 1 in P lividus sp nov is relatively short and triangular and curves awayfrom the medial line when viewed posteriorly while that of P sidneyi is relativelylonger more slender and more S-shaped The postfrontal crest of P sidneyi mayjoin the anterolateral margin at a relatively sharp angle and form a pronouncedepibranchial corner along the anterolateral margin The anterolateral margin inP lividus sp nov is more rounded and the epibranchial corners slope down to-wards the anks Potamonautes granularis is chocolate brown with orange tips tothe chelipeds Potamonautes brincki is a smaller crab with a smoother carapacethough also chocolate to reddish-brown in colour with a nely granulated antero-lateral margin which does not curve in over the carapace in the branchial region(Stewart 1997b) Potamonautes depressus and P clarus both have rounded epi-branchial corners and smooth carapaces though these are relatively shallow andhave attened dorsal surfaces Both are characterized by long slender limbs Pota-monautes depressus is brown to green-brown in colour while P clarus is brightorange in colour

158 G GOUWS B A STEWART amp P E REAVELL

A number of species from further a eld bear a super cial resemblance toP lividus sp nov particularly with regard to carapace morphology though in mostcases they can be readily distinguished Potamonautes pilosus Hilgendorf 1898 isknown from East Africa and is a small crab with a CWW of less than 25 mmSpecimens possess a weak postfrontal crest which along with the anterolateralmargin can be granulated (Hilgendorf 1898 Bott 1955) Potamonautes neumanniHilgendorf 1898 is known from East Africa and has a characteristically vaultedcarapace without a complete distinct postfrontal crest (Hilgendorf 1898 Bott1955) The postfrontal crest is more distinct in P lividus particularly laterally andthe exorbital teeth are sharper and more de ned in P lividus than in P neumanniThe terminal segment of gonopod 1 is longer and more slender in P neumannithan in P lividus and curves distinctly outwards The subterminal segment ofgonopod 1 is wider at its apex in P neumanni than in P lividus Additionally thecarapace of preserved specimens of P neumanni is typically grey in colour whileliving specimens are violet in colour with bright olive-green limbs and chelipeds(Hilgendorf 1898) Potamonautes ballayi acristatus Bott 1955 has an incompletepostfrontal crest only present above the orbits and small and blunt exorbital teethThe major chela although highly arched and the minor chela are long and moreslender than those of P lividus sp nov The terminal segment of gonopod 1 ofP granviki Colosi 1924 is curved towards the medial line when viewed posteriorly(Bott 1955) The chelae of both P berardi berardi Audouin 1826 and P b ignestiiParisi 1923 are relatively short and high with stout downward-projecting ngersThe anterior margin of the frontal lobe of P b berardi shows a distinct invaginationand the anterolateral margin appears sharp and less rounded than in P lividus spnov while the postfrontal crest of P b ignestii is complete and has a fairly longmedial groove Potamonautes emini emini Hilgendorf 1892 are generally smallcrabs with a less in ated carapace and short stout chelipeds The subterminaland terminal segments of gonopod 1 are of more or less equal size (Bott 1955)Potamonautes e semilunaris Bott 1955 and P luashiensis Bott 1955 are alsosmall crabs (CWW lt 20 mm) with the postfrontal crest only visible laterally andin the case of P luashiensis the anterolateral margin and postfrontal crest mayshow granulation Potamonautes didieri Rathbun 1904 possesses a more completerounded postfrontal crest and shorter more stout chelipeds (Bott 1955)

ACKNOWLEDGEMENTS

Financial assistance was kindly provided by the World Wildlife Fund - SouthAfrica the Foundation for Research Development and the University of ZululandThe KwaZulu-Natal Nature Conservation Services provided accommodation and

POTAMONAUTES LIVIDUS NOV 159

logistic support Liz Hoenson Peter Cook Mike Coke and Tyrone Ridgway arethanked for assistance in the eld and Michelle van der Merwe is thanked foraiding in the photography and drafting of gures The authors wish to thank ananonymous reviewer for comments on the manuscript

REFERENCES

BARNARD K H 1935 Scienti c results of the Vernay-Lang Kalahari expedition March toSeptember 1930 Crustacea Ann Transvaal Mus 16 481-492

mdash mdash 1950 Descriptive catalogue of South African decapod Crustacea (crabs and shrimps) AnnSouth African Mus 38 1-837

BOCK W J 1986 Species concepts speciation and macroevolution In K IWATSUKIP H RAVEN amp W J BOCK (eds) Modern aspects of species 31-57 (University of TokyoPress Tokyo)

BOTT R 1955 Die Suumlsswasserkrabben von Afrika (Crust Decap) und ihre StammesgeschichteAnn Mus R Congo Belge (C Zool) 1 (33) 209-352 pls 1-30

BRUTON M N 1980 An outline of the ecology of the Mgobezeleni lake system at Sodwana withemphasis on the mangrove community In M N BRUTON amp K H COOPER (eds) Studieson the ecology of Maputaland 408-426 (Rhodes University Grahamstown)

CUMBERLIDGE N 1986 Ventilation of the branchial chambers in the amphibious West Africanfreshwater crab Sudanonautes (Convexonautes) aubryi monodi (Balss 1929) (BrachyuraPotamonautidae)Hydrobiol 134 53-65

mdash mdash 1991 The respiratory system of Globonautes macropus (Rathbun 1898) a terrestrialfreshwater crab from Liberia (GecarcinucoideaGecarcinucidae)Crustaceana 61 (1) 69-80

DANIELS S R B A STEWART amp M J GIBBONS 1998a Potamonautes granularis sp nov(Brachyura Potamonautidae) a new cryptic species of river crab from the Olifants Riversystem South Africa Crustaceana 71 (8) 885-903

mdash mdash mdash mdash amp mdash mdash 1998b Genetic and morphometric variation in the potamonautid river crabPotamonautes parvispina (Decapoda Potamonautidae) from two Western Cape rivers SouthAfrica Journ nat Hist London 32 1245-1258

mdash mdash mdash mdash amp mdash mdash 1999 Genetic structure among populations of Potamonautes perlatus(Decapoda Potamonautidae) from the Olifants River system in the Western Cape SouthAfrica Journ Zool London 249 (2) 137-142

DIacuteAZ H amp G RODRIacuteGUEZ 1977 The branchial chamber in terrestrial crabs a comparative studyBiol Bull Woods Hole 153 485-504

GOUWS G B A STEWART amp M COKE 2000 Evidence for a new species of river crab(Decapoda Brachyura Potamonautidae) from the Drakensberg South Africa Journ CrustBiol 20 (4) 743-758

GREENAWAY P amp H H TAYLOR 1976 Aerial gas exchange in Australian arid-zone crabParathelphusa transversa Von Martens Nature London 262 711-713

HILGENDORF F 1898 Die Land- und Suumlsswasser-Dekapoden Ostafrikas Die Thierwelt DeutschOst-Afrikas 4 (7) 1-37

LENZ H 1912 Afrikanische Crustaceen aus schwedischen Sammlungen Ark Zool 7 (29) 1-10MARKERT C L amp I FAULHABER 1965 Lactate dehydrogenase isozyme patterns of sh Journ

exp Zool 159 319-332MAYR E 1963 Animal species and evolution i-xiv 1-797 (Harvard University Press Cambridge

Massachusetts)mdash mdash 1970 Populations species and evolution i-xv 1-453 (Harvard University Press Cambridge

Massachusetts)

138 G GOUWS B A STEWART amp P E REAVELL

INTRODUCTION

Freshwater crabs of the family Potamonautidae Bott 1970 are common through-out the rivers of KwaZulu-Natal South Africa Of the three species documentedfrom the province (Barnard 1935 1950) two Potamonautes sidneyi Rathbun1904 and Potamonautes dentatus Stewart Coke amp Cook 1995 are known to occurfrom the low-lying midlands to the coast

The earliest records of Potamonautes sidneyi from the rivers of the province dateback to 1910 Stebbing (1910) documented collections made at Port Natal Lenz(1912) referred to collections made at Lake Sibayi and elsewhere in Zululandand Barnard (1935) reported collections in the Transvaal Museum made atOliviershoek in the northern Drakensberg Potamonautes dentatus however hasonly recently been described from the Mgeni River Inyamvubu River and othertributaries of the Tugela River (Stewart et al 1995)

Collections made near Empangeni and Richards Bay revealed specimens thatcould not be identi ed as any of the species known from the province of KwaZulu-Natal The specimens were characterized by having a highly vaulted carapacea medially reduced postfrontal crest in ated arched chelipeds a downwardprojecting frontal lobe rounded downward sloping epibranchial corners anda characteristic silver-blue carapace sheen and bright orange to red chelipedsand pereopods The specimens appear to exclusively inhabit small patches ofswamp forest and associated herbaceous wetland with characteristic swamp forestvegetation assemblages (Wessels 1997) and spongy peat-soil in which thesecrabs form shallow U-shaped burrows partly lled with water The uniquemorphological characteristics and habitat requirements of this form raised thequestion whether it could be delineated as a species separate to those previouslyknown from the province

This paper provides empirical morphological and biochemical evidence for anew species of potamonautid river crab from the swamp forests of northeasternKwaZulu-Natal described as Potamonautes lividus sp nov Results are discussedagainst the broader evidence of variation and differentiation within the genusPotamonautes and the putative new species is compared to species known fromSouth Africa and further a eld

MATERIALS AND METHODS

Collection mdash Crabs were collected from ve localities ( g 1) using handnetsbaited with ox-heart Individuals of the undescribed form (form A) were easilyidenti able in the eld due to the much in ated carapace downward projecting

POTAMONAUTES LIVIDUS NOV 139

Fig 1 Sampling localities in northeasternKwaZulu-Natal South Africa

140 G GOUWS B A STEWART amp P E REAVELL

frontal lobe and characteristic colouration Potamonautes sidneyi (form B) indi-viduals could be identi ed following the descriptions and illustrations of Barnard(1950) and Bott (1955) by the presence of a sharp postfrontal crest scabrosityof the epibranchial corners and broad limbs Individuals of the undescribed form(form A) were collected from a patch of swamp-forest dominated by Syzygiumcordatum Hochst (common waterberry) trees and characterized by spongy hy-dromorphic peat soil at the University of Zululand campus a similar forest alongthe Mdibi stream (an af uent of Lake Mzingazi) north of Richards Bay and aFicus trichopoda Bak and Barringtonia racemosa (L) Roxb dominated swamp-forest near the Mapelane Nature Reserve Populations of P sidneyi were sampledfrom marshy grassland near Dakaneni village outside Hluhluwe Game Reserveand the upper reaches of the Manzibomvu River within the Hluhluwe Game Re-serve Potamonautes sidneyi populations were also sampled from the University ofZululand campus and Mdibi swamp-forest where they occur sympatrically withthe undescribed form (form A) Crabs were killed by overnight freezing Unfor-tunately specimens of P sidneyi from the Mdibi swamp-forest were unsuitablefor genetic analysis as specimens were processed days after capture and proteindenaturation could not be avoided due to repeated freezing and thawing duringtransportation

Biochemical analysis mdash Muscle and digestive-gland tissue (hepatopancreas)were removed from each specimen by dissection Tissue samples were stored incryogenic tubes at iexcl80plusmnC until electrophoresis was ready to be performed Tissuewas homogenized in 001 M Tris buffer (pH 8) using a glass rod attached to avariable-speed electric motor The samples were centrifuged for ve minutes at12000 rpm prior to use Filter paper wicks (Whatmans 3) were dipped into thesupernatant and inserted into the horizontal 13 starch gel (Sigma Chemicals CoSt Louis Missouri USA)

Three electrophoretic buffer systems were used (A) a discontinuous Tris-citrate-borate-lithium hydroxide buffer with a gel buffer pH 87 and an electrodebuffer pH 80 (Ridgeway Sherburne amp Lewis 1970) (B) a continuous Tris-borate-EDTA buffer system at pH 86 (Markert amp Faulhaber 1965) and (C) a continuousTris-citrate buffer system at pH 69 (Whitt 1970) Gels were run inside a fridge(4plusmnC) for 4 hours at 40 mA These were then sliced horizontally into 3 or 4 slicesand the sites of enzymatic activity histochemically stained in a 2 agar overlay(Shaw amp Prasad 1970)

Of 24 isozyme loci originally screened 21 were reliably interpretable andincluded in the analyses (table I) A sample of Potamonautes depressus Krauss1843 from the Coleford Nature Reserve was included in each run as a referencepopulation to provide continuity in scoring across all populations For each locusthe most common allele of the Coleford population was assigned a value of 100

POTAMONAUTES LIVIDUS NOV 141

TABLE IEnzymes and buffer systems used to determine biochemical variation in six populations of Potamo-

nautes spp studied

Enzyme Abbreviation EC Number Buffer Tissue Loci

Arginine kinase ARK 2733 A m 1Diaphorase DIA 1622 A h 1Glucose-6-phosphateisomerase GPI 5319 A m 1Hexokinase HEX 2711 B m 1Isocitrate dehydrogenase IDH 11142 C m 2Lactate dehydrogenase LDH 11127 A m 1Malate dehydrogenase MDH 11137 C m 2Malic enzyme ME 11140 B m 1Mannose-phosphate isomerace MPI 5318 B m 1Peptidase (glycyl-leucine as substrate) GL 3411ndash B m 1Peptidase (leucyl-glycyl-glycylas substrate) LGG 3411ndash A h 3Peptidase (leucyl-tyrosineas substrate) LT 3411ndash A B m h 2Peptidase (phenylamine-prolineas substrate) PHP 3411ndash B h 1Phosphoglucomutase PGM 5422 B m 2Phosphoglusonatedehydrogenase PGD 11144 C m 1

Buffer (A) discontinuous Tris-citrate-borate-lithium hydroxide buffer system (Ridgeway et al1970) (B) continuous Tris-borate-EDTA buffer system (Markert amp Faulhaber 1965) and (C) con-tinuous Tris-citrate buffer system (Whitt 1970) Tissue (m) muscle tissue and (h) hepatopancreas (digestive gland)

and all other alleles were scored relative to this value Where more than one locusstained for a particular enzyme the most anodally migrating one was labeled 1and the others labeled sequentially

All numerical analyses were performed using the BIOSYS-1 program (Swof-ford amp Selander 1981) Allele and genotype frequencies were calculated Geno-type frequencies were tested for deviation from frequencies expected under Hardy-Weinberg equilibrium by means of a Acirc2-goodness-of- t test Where more than twoalleles occurred at a locus the genotype frequencies were pooled Percentage poly-morphic loci were calculated for each population using no criterion (loci wereconsidered polymorphic if more than one allele was present at a locus) The meanexpected heterozygosity (H) was also calculated for each locus using unbiasedestimates (Nei 1978) The mean unbiased genetic identity (I ) and distance (D)were calculated for each pairwise comparison (Nei 1978) and a dendrogram con-structed using the measures of genetic identity and the UPGMA clustering algo-rithm (Sneath amp Sokal 1973)

Morphological analyses mdash Prior to dissection crabs were sexed and measuredusing digital Vernier-calipers and a portable computer The populations used forthe genetic analysis were supplemented with morphometric data from specimens

142 G GOUWS B A STEWART amp P E REAVELL

collected earlier at the above localities Seven carapace variables were recorded formorphometric analyses These were carapace length along the medial line (CL)carapace width at the widest part (CWW) posterior carapace width (CWP) thedistance between the postfrontal crest and the anterior carapace margin (PFCD)distance between the medial margins of the orbits (ED) distance between theexorbital teeth (CWA) and the carapace height (CH)

Data were log transformed (common logarithms) prior to analysis All statisticalanalyses were performed using the Statistica Version 51 program (StatSoft Inc1996) Morphological variation between the two forms was determined by meansof a stepwise discriminant function analysis using seven carapace variablesClassi cation functions were calculated using the jackknife procedure ensuringan unbiased classi cation function for determining group assignment Individualswere then reassigned to a group based on the highest a posteriori probability Afrequency histogram of individual canonical variable scores calculated from thediscriminant function analysis was plotted to reveal discrimination between thetwo forms Linear regression analyses were used to test for variation within speci cvariables between the two forms

Gonopods and mouthparts were removed and examined qualitatively using aLeitz stereoscopic dissection microscope and illustrated using a camera lucida orphotographed using a Wild MPS45 camera unit

RESULTS

Biochemical analysis mdash Of the 21 reliably scorable loci nine (ARK LT-1ME LDH MPI PGD DIA LGG-1 and LGG-3) were monomorphic across allpopulations analysed Twelve loci were polymorphic (table II) The LT-2 locus wasthe only locus polymorphic in each population The total number of alleles rangedfrom two in HEX MDH-1 IDH-1 GL PGM-2 PHP-2 and LGG-2 to ve in GPIWithin populations the maximum number of alleles was four found in GPI in theManzibomvu population

Out of thirty cases of polymorphism for all enzyme loci and populations three(10) were shown to deviate from genotype frequencies expected under Hardy-Weinberg equilibrium The LT-2 locus in the University of Zululand A population(Acirc2 D 9468 df D 3 P D 0024) the PHP locus in the Mdibi population(Acirc2 D 7037 df D 1 P D 0008) and the PGM-2 locus in the Dakanenipopulation (Acirc2 D 250 df D 1 P D 0000) were out of equilibrium due toa de cit of heterozygotes carrying the rare allele All other loci conformed toHardy-Weinberg expectations thus supporting a purely genetic interpretation ofthe polymorphisms observed

POTAMONAUTES LIVIDUS NOV 143

TABLE IIDistribution of allele frequencies at nine polymorphic loci in six populations of Potamonautes spp

studied N D sample size refer to table I for enzyme abbreviations

Population

Locus Zululand A Mdibi Mapelane Zululand B Dakaneni Manzibomvu

IDH-2N 41 24 25 13 25 13120 0012 0729 0380 0000 0000 000080 0988 0229 0000 1000 1000 100045 0000 0043 0620 0000 0000 0000

GPIN 56 26 25 13 25 13165 0045 0000 0000 0000 0000 0000150 0000 0000 0000 0000 0000 0038100 0000 0000 0000 0000 0000 003840 0938 1000 1000 0962 0880 0846

iexcl80 0018 0000 0000 0038 0120 0077

HEXN 41 26 25 13 25 13100 1000 1000 1000 0000 0000 000095 0000 0000 0000 1000 1000 1000

MDH-1N 41 26 25 13 25 13100 0988 1000 1000 1000 1000 100090 0012 0000 0000 0000 0000 0000

MDH-2N 41 26 25 13 25 13100 1000 1000 1000 0962 0960 100075 0000 0000 0000 0000 0040 000065 0000 0000 0000 0038 0000 0000

IDH-1N 41 26 25 13 23 7150 0000 0000 0000 1000 0891 0929135 1000 1000 1000 0000 0109 0071

LT-2N 41 26 25 13 25 13250 0049 0019 0020 0000 0000 0000100 0854 0885 0840 0923 0980 0769

0 0098 0096 0140 0077 0020 0231

PGM-1N 52 26 25 13 25 13110 0365 0000 0000 0000 0000 0000100 0212 0000 0000 0038 0140 003890 0423 1000 1000 0923 0800 096275 0000 0000 0000 0038 0060 0000

(continued overleaf)

144 G GOUWS B A STEWART amp P E REAVELL

TABLE II(Continued)

Population

Locus Zululand A Mdibi Mapelane Zululand B Dakaneni Manzibomvu

GLN 41 26 25 13 25 1390 1000 0962 1000 1000 1000 100075 0000 0038 0000 0000 0000 0000

PGM-2N 56 26 25 13 25 13100 1000 1000 1000 0000 0040 000075 0000 0000 0000 1000 0960 1000

PHPN 41 26 25 13 25 13105 1000 0808 1000 1000 1000 100090 0000 0192 0000 0000 0000 0000

LGG-2N 41 26 25 13 24 13100 0854 0942 1000 0846 0979 069290 0146 0058 0000 0154 0021 0308

Genetic variability was low in all populations The percentage polymorphicloci (no criterion) ranged from 95 to 333 in the Mapelane and Dakanenipopulations respectively The mean unbiased expected heterozygosity varied from0034 (in the University of Zululand B population) to 0063 (in the Universityof Zululand A and Manzibomvu populations) The mean number of alleles perlocus ranged from 11 (in the Mapelane population) to 14 (in the Dakaneni andUniversity of Zululand A populations)

The dendrogram constructed based on the genetic identity values obtained bypairwise comparison of populations (table III) clearly distinguished two clusters( g 2) The group representing the form A populations clearly separated from thegroup representing the form B (Potamonautes sidneyi) populations at a geneticidentity value of I D 0829 D D 0187 Three loci contributed signi cantly tothis separation one of them diagnostically The HEX locus showed a xed alleledifference between the individuals of the two forms with the form A individualsbeing xed for the allele HEX100 and the form B (P sidneyi) individuals xed forthe HEX95 allele Strong heterogeneity was observed between the populations ofthe two forms at the IDH-1 and PGM-2 loci With the exception of one individualin the Dakaneni population having a homozygote with the PGM-2100 allele form Aand form B were characterized by the xation of alleles PGM-2100 and PGM-275

POTAMONAUTES LIVIDUS NOV 145

TABLE IIICoef cient matrix of Neirsquos (1978) unbiased genetic identity (above diagonal) and unbiased geneticdistance (below diagonal) for pairwise comparisons of the six populations of Potamonautes studied

Population

Zululand A Mdibi Mapelane Zululand B Dakaneni Manzibomvu

Zululand A currencurrencurrencurrencurren 0958 0949 0840 0855 0842

Mdibi 0043 currencurrencurrencurrencurren 0986 0821 0832 0822

Mapelane 0052 0014 currencurrencurrencurrencurren 0813 0825 0814

Zululand B 0174 0197 0206 currencurrencurrencurrencurren 0998 0999

Dakaneni 0157 0184 0193 0002 currencurrencurrencurrencurren 0994

Manzibomvu 0172 0196 0206 0001 0006 currencurrencurrencurrencurren

Fig 2 UPGMA dendrogram constructed from the matrix of Neirsquos (1978) unbiased genetic identi-ties (I ) using allozyme data from 21 loci

respectively Identity-values for within form comparisons varied from 0949 to0986 (D D 0014 to 0052) and 0994 to 0999 (D D 0001 to 0006) for form Aand form B respectively

Morphometric analysis mdash Individuals from the form A populations couldeasily be distinguished from the form B (P sidneyi) individuals by the possessionof a much more vaulted carapace in ated chelipeds a postfrontal crest whichdiminishes medially and the characteristic silver-blue carapace sheen and brightorange to red chelipeds and pereopods Mature form B (P sidneyi) individualsfrequently attained a larger size class (with CL being representative of size) thandid the mature form A individuals

146 G GOUWS B A STEWART amp P E REAVELL

Three carapace variables (ED CH and CWP) contributed signi cantly to thediscrimination between the two forms in the discriminant function analysis Thehistogram plot of observed canonical variable scores ( g 3) clearly separates thetwo forms with the canonical variable means of the form A and form B individualscalculated at iexcl0996 and 1965 respectively The classi cation function (the linearfunction of variables which best discriminates the individuals of one group fromthe other speci ed groupings) was calculated for individuals of each form Theclassi cation function of the form A group was

Y D 306704 (Log CWP) iexcl 26103 (Log ED) iexcl 228513 (Log CH) iexcl 64156

and of the form B (P sidneyi) group

Y D 35097 (Log ED) iexcl 315543 (Log CH) C 347231 (Log CWP) iexcl 88367

Using the classi cation functions individuals were reassigned to groups basedon highest a posteriori probabilities Of the form A individuals 9437 (134of 142) were correctly classi ed with eight individuals being reassigned to theform B group Of the form B individuals 8889 were correctly reassigned to theP sidneyi group with eight of the 72 individuals being reassigned to the form Agroup

Fig 3 Histogram of scores for specimens of Potamonautes lividus sp nov (form A) and P sidneyiRathbun 1904 (form B) along the canonical variable calculated from a discriminant function

analysis using seven carapace variables

POTAMONAUTES LIVIDUS NOV 147

Comparison of regressions of the most discriminating variables between the twoforms regressed over CL in turn also showed signi cant differences between thetwo forms CH regressed over CL showed highly signi cant differences betweenthe two forms (SS D 0011 df D 1 F D 31266 P lt 0001) as did ED(SS D 0011 df D 1 F D 8333 P lt 0005) and CWP (SS D 0006 df D 1F D 8136 P lt 0005) These represent the most discriminating variables andtheir regressions are represented graphically ( g 4a b c) PFCD (SS D 0199df D 1 F D 52671 P lt 0001) CWW (SS D 0003 df D 1 F D 30963P lt 0001) and CWA (SS D 0001 df D 1 F D 6182 P lt 002) also showedthat there were signi cant differences between the two forms but the discriminantfunction analysis showed them to be redundant in constructing the model

Qualitative analysis mdash Examination of gonopods and mouthparts revealed onlyslight differences in gonopod morphology The terminal segment of gonopod 1of the undescribed form was relatively short and triangular whereas the terminalsegment of gonopod 1 of P sidneyi appears to be substantially longer and moreslender Although the terminal segment is bent away from the medial line in bothforms the terminal segment in P sidneyi possesses a lobe or ange that extendsinwards giving the terminal segment an S-shaped appearance The gonopods andmandibular palps of the two forms are illustrated in g 5

DISCUSSION

The data presented above clearly indicate that the two forms of freshwatercrabs from KwaZulu-Natal are distinct The form A specimens are smaller with amore vaulted carapace that is relatively narrower posteriorly and that possessesa relatively narrower frontal lobe (ED) than that of the Potamonautes sidneyiindividuals

Not only are the two forms clearly distinct both biochemically and morpho-logically but strong evidence suggests that they are reproductively isolated Thepresence of a diagnostic locus HEX xed for alternate alleles in the sympatricpopulation of the two forms indicates that a lack of gene ow and thus repro-ductive isolation exist between the two forms This allows for species recognitionunder the Biological Species Concept (Mayr 1970) under which species are de- ned as ldquogroups of actually or potentially interbreeding populations which arereproductively isolated from other such groupsrdquo (Mayr 1963 19) or ldquogeneticallyisolated (in nature) from other such groupsrdquo (Bock 1986 33) In his model of al-lopatric speciation Bock (1986) suggested that newly evolved species in sympatrywould exert mutually selective demands on each other by means of reproductive

148 G GOUWS B A STEWART amp P E REAVELL

Fig 4 Comparisons of the regressions of (A) Log CH (carapace height) over Log CL (carapacelength) (B) Log ED (eye distance) over Log CL and (C) Log CWP (posterior carapace width) overLog CL between form A (Potamonautes lividus sp nov) and form B (P sidneyi Rathbun 1904) All

differences are signi cant (at the P lt 0005 level)

POTAMONAUTES LIVIDUS NOV 149

Fig 5 A-E form A (Potamonautes lividus sp nov composite of male holotype SAM A43540and unaccessioned material) A carapace outline B left mandibular palp anterior view C leftmandibular palp posterior view D left gonopod 1 anterior view and E left gonopod 1 posteriorview F-J form B (Potamonautes sidneyi Rathbun 1904 unaccessioned specimen) F carapaceoutline G left mandibular palp anterior view H left mandibular palp posterior view I left

gonopod 1 anterior view J left gonopod 1 posterior view

150 G GOUWS B A STEWART amp P E REAVELL

interference and ecological competition This would lead to a divergence of mor-phological and behavioural aspects of feeding reproduction and other ecologicalfeatures The different gonopod morphologies of the two forms may re ect this

The three form A populations clustered separately from the three P sidneyipopulations at a I -value of 0829 Stewart (1997a) calculated the separationI -value between P parvispina Stewart 1997 and P perlatus H Milne Edwards1837 to be 068 An I -value of 066 separated both P perlatus and P brinckiBott 1960 in the Western Cape (Stewart 1997b) and P unispinus Stewart ampCook 1998 and P sidneyi in Mpumalanga (Stewart amp Cook 1998) An I -valueof 0599 was obtained separating P clarus Gouws Stewart amp Coke 2000 andP depressus (Gouws et al 2000) The only species in the genus delineated using ahigher I -value was P granularis Daniels Stewart amp Gibbons 1998 which wasseparated from P perlatus in the Olifants River at a I -value of 088 (Danielset al 1998a 1999) Although slightly higher than most interspeci c values inthe genus the value obtained in this study nevertheless falls within the range (035to 085) speci ed by Thorpe (1982) to indicate congeneric species differencesAllopatric populations showing I -values of less than 085 are unlikely to beconspeci c (Thorpe amp Soleacute-Cava 1994) With the exception of two cases allpairwise comparisons between allopatric populations of the two forms yieldedI -values less than 085

Identity-values were high for comparisons within both the form A (0949 to0986) and P sidneyi (0994 to 0999) groups Intraspeci c I -values are generallyhigh in the genus Potamonautes and disjunct populations within a species tendto be genetically undifferentiated Intraspeci c I -values obtained in six studies(Stewart 1997a b Stewart amp Cook 1998 Daniels et al 1998b 1999) involvingsix Potamonautes species varied from 0902 to 1000 (D D 0000 to 0103)An intraspeci c I -value of 075 was obtained in a comparison of two groups ofP brincki populations across the Cape Peninsula and Cape Flats However thismost probably indicates a species difference and requires further investigation(Stewart 1997b) Given the high intraspeci c I -values characteristic of the genusand those obtained for comparisons within each form the I -value obtainedfor the comparison between the two forms most likely represents a speciesdifference

Bock (1986) also de ned a species as possessing a set of three distinctcharacteristics genetic unity reproductive unity and ecological unity Biochemicaldata provide support for compliance with the rst two criteria for both formsWhile no empirical evidence is as yet available con rming the third factor adegree of macro- and microhabitat segregation and thus ecological segregationis evident between the two forms Potamonautes sidneyi is widespread acrossthe province (Stewart et al 1995) while the other form appears to have a

POTAMONAUTES LIVIDUS NOV 151

more limited distribution in northeastern KwaZulu-Natal restricted to patches ofswamp forest with particular oral assemblages The swamp forests are oftencharacterized by Barringtonia racemosa Syzygium cordatum Ficus trichopodaHibiscus tiliaceus L Rauvola caffra Sond Voacanga thouarsii Roem amp SchultRaphia australis Oberm amp Strey and Podocarpus falcatus (Thunb) R Br exMirb with the fern Stenochlaena tenuifolia (Desv) T Moore often present in theunderstorey (Bruton 1980 Moll 1980) Within the swamp forests the sympatricpopulations appear to show a degree of microhabitat segregation Observationssuggest that P sidneyi has a closer association with water as individuals were nevercollected great distances away from seepage pools and channels owing throughthe forest Conversely individuals of the swamp-forest form were most oftencollected farther from water and their burrows were often among the vegetationObservations suggest that this form is more terrestrial Individuals were noticedto move to higher elevations when the water table rose through the hydromorphicpeat soil ooding their burrows and the surface and they were also more active oncloudy overcast days Evidence of terrestrial adaptation is most likely to be foundin the structure and histology of the organs and tissues involved in respirationfactors such as branchial chamber shape and volume gill structure and formulaand the structure and vascularization of the branchiostegite lining are knownto re ect changes brought upon by the constraints of the terrestrial environment(Greenaway amp Taylor 1976 Diacuteaz amp Rodriacuteguez 1977 Taylor amp Greenaway1979 Cumberlidge 1986 1991 Takeda et al 1996) Although the availabilityof material prohibited the investigation of this aspect future research may prove tobe fruitful and highlight a greater distinction between the two forms

Studies on terrestrial adaptation supplemented by behavioural data that couldillustrate microhabitat and ecological segregation would quantify further thedegree of differentiation between the two forms However two independent datasets biochemical and morphological present strong evidence for the speci c statusof the swamp-forest form

TAXONOMY

Potamonautes lividus sp nov ( gs 6-7)

Material examined mdash Holotype South African Museum (SAM) A43540 one male CL D255 mm Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws andL Hoenson Allotype SAM A43541 one female CL D 245 mm Ficus and Barringtonia swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S 32plusmn2401800E)coll 27 January 1997 by B A Stewart G Gouws and L Hoenson Other material SAM A43542two males Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws

152 G GOUWS B A STEWART amp P E REAVELL

and L Hoenson SAM A43543 one female Lake Nhlabane north of Richards Bay (28plusmn3800500S32plusmn1601700E) coll 27 April 1993 by the University of Zululand Zoology Department SAMA43544 three males one female Mdibi swamp forest along Mdibi stream 8 km north of RichardsBay (28plusmn4202400S 32plusmn0902600E) coll 26 January 1997 by B A Stewart P A Cook M CokeP E Reavell G Gouws and L Hoenson SAM A43545 one male one female Syzygium forestUniversity of Zululand campus (28plusmn5102500S 31plusmn5100200E) coll 24 January 1997 by B A StewartP A Cook P E Reavell G Gouws and L Hoenson SAM A43546 two males two femalesUniversity of Zululand stream owing through campus (28plusmn550S 31plusmn410E) coll 10 September 1995by P E Reavell SAM A41313 one male one female swamp forest Empangeni (28plusmn5102500S31plusmn5100200E) coll 2 August 1994 by M Coke SAM A41155 one male University of ZululandSyzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S 31plusmn450E) coll 10 December1988 by P E Reavell SAM A41153 three males smaller holes in hydromorphic soil Syzygiumcordatum swamp forest University of Zululand (28plusmn450S 31plusmn450E) coll 20 March 1994 byP E Reavell SAM A41156 one female Syzygium cordatum swamp forest University of Zululand(28plusmn450S 31plusmn450E) coll 18 May 1992 by P E Reavell SAM A41154 one male one femaleUniversity of Zululand Syzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S31plusmn450E) coll 10 May 1990 by P E Reavell SAM A43547 two males one female swamp forestUniversity of Zululand (28plusmn450S 31plusmn450E) coll 1 April 1994 by P E Reavell SAM A43548one male one female Syzygium and Bridelia dominated swamp forest University of Zululand(28plusmn5102500S 31plusmn5100200E) coll 7 October 1996 by P E Reavell SAM A43549 one female Mdibiswamp forest Lake Msingazi catchment area north of Richards Bay (28plusmn420S 32plusmn090E) coll5 December 1996 by P E Reavell Albany Museum mdash GEN910 one female Mpolozi swampsMapelane (28plusmn2601300S 32plusmn2402500E) coll 13 February 1991 Albany Museum mdash GEN965 twomales ve females NrsquoKoninga Valley Richards Bay (28plusmn450S 32plusmn030E) coll 7 April 1988

Other material mdash The following specimens included in the collections of the South AfricanMuseum warrant further investigation as although they bear some resemblance to the speciesdescribed below their identi cation is uncertain SAM A41276 one male one female Mbonenidam Mkuze Game Reserve (27plusmn3705700S 32plusmn1504500E) coll 28 October 1994 by M Coke SAMA41299 two males Nxwala stream Mkuze Game Reserve (27plusmn4302300S 32plusmn1601000E) coll 10November 1994 by O Bourquin SAM A41277 one male Rainpool south of entrance False BayPark (28plusmn0000100S 32plusmn2102100E) coll 26 October 1994 by M Coke SAM A41300 two malesKangela rainpoolN2 near Mtubatuba (28plusmn2200000S 32plusmn1103600E) coll 25 October 1994 by M Cokeand SAM A41211 one male Ntambanana (Ntrabanana) Zululand coll by H H Curson

Type locality mdash South Africa KwaZulu-Natal Barringtonia and Ficus swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S32plusmn2401800E)

Distribution mdash At present known only from the swamp forests (characterizedby Barringtonia racemosa Syzygium cordatum and Ficus trichopoda vegetationand spongy hydromorphic peat-soil) in the vicinity of Richards Bay Empangeniand the Mapelane Nature Reserve It is probable that the distribution of the speciesmay extend into low-lying areas to the east of the Drakensberg escarpment in theprovince of Mpumalanga and into Mozambique

Etymology mdash From the Latin ldquolividusrdquo meaning ldquobluerdquo or ldquolight bluerdquoreferring to the characteristic silver-blue sheen of the carapace The epitheton isan adjective agreeing in gender with the (masculine) generic name

POTAMONAUTES LIVIDUS NOV 153

Fig 6 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A wholeanimal dorsal aspect B whole animal ventral aspect C cephalothorax frontal aspect

Diagnosis mdash Carapace distinctly vaulted and relatively narrow posteriorlyEpibranchial teeth absent and anterolateral margin of the carapace smooth Post-frontal crest indistinct medially with frontal lobe projecting downwards Cara-pace characteristically orange to red with silver-blue sheen Chelipeds and limbs

154 G GOUWS B A STEWART amp P E REAVELL

bright orange to red with lighter cheliped and dactyl tips Chela in ated and highlyarched

Description of male holotype mdash Size Measurements of the holotype and theranges of other specimens are given in table IV

Carapace ( gs 6A C 7A) Carapace and limbs characteristically orange tored with the carapace possessing a silver-blue sheen when alive Preserved spec-imens (70 ethanol) appear less orange and the carapace retains a blue-greycolour Cephalothorax ovoid distinctly vaulted branchial region highly convex( g 6A C) maximum height and width at anterior third (ratio CHCL D 065CWWCL D 145) Anterior margin straight Urogastric grooves moderately wellde ned Cardiac grooves shallow and poorly de ned Carapace otherwise smoothPostfrontal crest smooth curves forward medially Postfrontal crest diminishesabove inner orbit margins though well de ned immediately lateral to forked mid-point groove by means of two indentations anterior to crest indicating epigas-tric lobes Exorbital teeth moderately sharp but small Epibranchial teeth ab-sent Anterolateral margin posterior to postfrontal crest smooth margin curvingin over carapace in branchial region though indistinctly Each ank has a longitu-dinal groove dividing the subhepatic from the pterygostomial region with verticalgroove running from longitudinal groove joining anterolateral margin between ex-orbital tooth and postfrontal crest

Sternites ( gs 6B 7B) Sternites 1 and 2 fused no suture visible First suture(sternal groove) between sternites 2 and 3 complete Second sternal groove

TABLE IVPotamonautes lividus sp nov wet weight (in g) and measurements (in mm) for the male holotype

and ranges for other individuals examined (maximum of 77 males and 70 females)

Variable Abbreviation Holotype Males Females

Wet weight WW 242 05-214 07-183Carapace length CL 255 84-247 89-276Carapace widest width CWW 370 114-360 118-373Carapace posterior width CWP 281 90-269 86-306Distance between postfrontal crest

and anterior margin PFCD 43 12-222 15-46Distance between orbits ED 114 42-119 43-123Distance between exorbital teeth CWA 259 96-254 96-262Carapace height CH 165 48-171 50-162Width of sixth abdominal segment AW6 75 28-74 31-240Major cheliped propodus length MCPL 427 71-402 76-291Major cheliped propodus height MCPH 198 28-189 28-142Pereopod 2 merus length P2ML 189 50-181 51-171Pereopod 2 merus width P2MW 58 19-56 18-59

POTAMONAUTES LIVIDUS NOV 155

Fig 7 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A carapaceoutline B thoracic sternum C right cheliped dactylus and propodus D left cheliped dactylusand propodus E left third maxilliped F left mandible and mandibular palp posterior view G leftmandibular palp posterior view H left mandibular palp anterior view I left gonopod 1 anteriorview J terminal segment left gonopod 1 anterior view K left gonopod 1 posterior view L leftgonopod 2 anterior view Scale lines represent 1 mm except for A-D where they represent 10 mm

156 G GOUWS B A STEWART amp P E REAVELL

between sternites 3 and 4 complete laterally becoming shallower mediallysloping sharply towards abdominopelvic region

Third maxillipeds ( gs 6C 7E) Filling entire buccal frame except for ovalefferent respiratory openings short agellum present on exopods ischium smoothwith moderately deep vertical groove

Mandibular palp ( g 7F G H) Mandibular palp with two segments terminalsegment undivided with a dense tuft of setae on posterior surface of angeof terminal segment Margins generally hirsute Subterminal segment slightlyenlarged distally

Chelipeds and walking legs ( gs 6A 7C D) Chelipeds markedly unequaldactylus of right cheliped strongly arched 163 times length of dactylus of leftcheliped Both dactyli armed with up to 20 cutting teeth three to four of whichare slightly larger and more prominent Propodus of right cheliped markedlyin ated 168 times longer and 20 times wider than that of left cheliped Pollexpossesses 20 cutting teeth four to ve of which are more prominent Carpi ofboth chelipeds possess one prominent and three rudimentary teeth Margins ofmeri granulose small blunt spine on anterior surface no spine on anterior-inferiormargin Pereopods generally slender (pereopod 2 merus length width D 328 andpereopod 5 merus lengthwidth D 271) P3 longest P5 shortest ventral marginsof propodi and meri smooth dorsal margin with ne sharp bristles dactyli endingin sharp points with margins bearing a series of sharp spinelike bristles

Pleon ( gs 6B 7B) First ve segments broad and short last two segmentslonger terminal segment rounded at distal end

Pleopods ( g 7I J K) Pleopod 1 (gonopod 1) terminal segment short 025times length of subterminal segment terminal segment curves away from mid-line when viewed posteriorly widest at base ending in pointed tip Subterminalsegment of pleopod 1 tapers distally inner lateral margin slightly irregular outerlateral margin straighter both margins hirsute Posterior surface with twisting lon-gitudinal groove extending length of subterminal and terminal segment Groovenot visible on anterior surface Posterior surface and margins of groove hirsutePleopod 2 (gonopod 2) terminal segment lament-like 05 the length of subter-minal segment curving slightly towards medial line proximally curves away frommedial line distally ( g 7L) Subterminal segment widest at base tapering sharplyinwards at 04 of length forms narrow process supporting terminal segment

Variation mdash All individuals are characteristically dark orange to red witha silver-blue sheen to the carapace while the chelipeds vary in colour frombright orange-red to a lighter yellow-orange All individuals are characterized byhighly vaulted carapaces and downwardly projecting frontal lobes The postfrontalcrest which is most pronounced laterally (from directly above the orbits to theanterolateral margin) and incomplete medially is often more distinct in the smaller

POTAMONAUTES LIVIDUS NOV 157

individuals Chelipeds are not always typically arched enclosing a large ovoidspace as in the holotype Chelipeds of smaller individuals although in ated areless arched and often tight closing with the small cutting teeth more obviousChelipeds of females and small males in particular from the Mdibi and Universityof Zululand localities have propodi that are relatively high with in ated palmsand relatively short tightly closing chelae which project slightly downwardsHeterochely has been demonstrated in most Potamonautes-species occurring inSouth Africa (Siegfried 1972 Raubenheimer 1986 Stewart et al 1995 Stewart1997a b Stewart amp Cook 1998 Daniels et al 1998a Gouws et al 2000) Withinthe species 76 of the specimens were right-handed with 11 being left-handedand 13 being of equal or subequal (differing by less than one millimeter) sizeOf the males 79 were right-handed 8 left-handed and 13 equal or subequalFemales had 74 right-handedness 13 left-handedness and in 13 of caseschelipeds were equal or subequal The abdomen of mature females completelyoverlaps the coxae of the pereopods The smallest mature female had a CL of167 mm with the largest immature female having a CL of 159 indicating that thepubertal moult occurs approximately between the 14 mm and 18 mm size classes

Remarks mdash Potamonautes lividus sp nov can readily be distinguished from theten other species in the genus Potamonautes known to occur within South AfricaPotamonautes warreni Calman 1918 P dentatus P parvispina and P unispinusall bear a singular spine or a series of teeth on the anterolateral margins whereasP lividus sp nov is smooth Potamonautes perlatus P sidneyi and P granularisare all larger crabs with in ated arched carapaces with complete distinct post-frontal crests and scabrosity or granulation of the anterior margins orbits epi-branchial corners or postfrontal crests Potamonautes lividus sp nov has smoothcarapace margins and a incomplete postfrontal crest The terminal segment ofgonopod 1 in P lividus sp nov is relatively short and triangular and curves awayfrom the medial line when viewed posteriorly while that of P sidneyi is relativelylonger more slender and more S-shaped The postfrontal crest of P sidneyi mayjoin the anterolateral margin at a relatively sharp angle and form a pronouncedepibranchial corner along the anterolateral margin The anterolateral margin inP lividus sp nov is more rounded and the epibranchial corners slope down to-wards the anks Potamonautes granularis is chocolate brown with orange tips tothe chelipeds Potamonautes brincki is a smaller crab with a smoother carapacethough also chocolate to reddish-brown in colour with a nely granulated antero-lateral margin which does not curve in over the carapace in the branchial region(Stewart 1997b) Potamonautes depressus and P clarus both have rounded epi-branchial corners and smooth carapaces though these are relatively shallow andhave attened dorsal surfaces Both are characterized by long slender limbs Pota-monautes depressus is brown to green-brown in colour while P clarus is brightorange in colour

158 G GOUWS B A STEWART amp P E REAVELL

A number of species from further a eld bear a super cial resemblance toP lividus sp nov particularly with regard to carapace morphology though in mostcases they can be readily distinguished Potamonautes pilosus Hilgendorf 1898 isknown from East Africa and is a small crab with a CWW of less than 25 mmSpecimens possess a weak postfrontal crest which along with the anterolateralmargin can be granulated (Hilgendorf 1898 Bott 1955) Potamonautes neumanniHilgendorf 1898 is known from East Africa and has a characteristically vaultedcarapace without a complete distinct postfrontal crest (Hilgendorf 1898 Bott1955) The postfrontal crest is more distinct in P lividus particularly laterally andthe exorbital teeth are sharper and more de ned in P lividus than in P neumanniThe terminal segment of gonopod 1 is longer and more slender in P neumannithan in P lividus and curves distinctly outwards The subterminal segment ofgonopod 1 is wider at its apex in P neumanni than in P lividus Additionally thecarapace of preserved specimens of P neumanni is typically grey in colour whileliving specimens are violet in colour with bright olive-green limbs and chelipeds(Hilgendorf 1898) Potamonautes ballayi acristatus Bott 1955 has an incompletepostfrontal crest only present above the orbits and small and blunt exorbital teethThe major chela although highly arched and the minor chela are long and moreslender than those of P lividus sp nov The terminal segment of gonopod 1 ofP granviki Colosi 1924 is curved towards the medial line when viewed posteriorly(Bott 1955) The chelae of both P berardi berardi Audouin 1826 and P b ignestiiParisi 1923 are relatively short and high with stout downward-projecting ngersThe anterior margin of the frontal lobe of P b berardi shows a distinct invaginationand the anterolateral margin appears sharp and less rounded than in P lividus spnov while the postfrontal crest of P b ignestii is complete and has a fairly longmedial groove Potamonautes emini emini Hilgendorf 1892 are generally smallcrabs with a less in ated carapace and short stout chelipeds The subterminaland terminal segments of gonopod 1 are of more or less equal size (Bott 1955)Potamonautes e semilunaris Bott 1955 and P luashiensis Bott 1955 are alsosmall crabs (CWW lt 20 mm) with the postfrontal crest only visible laterally andin the case of P luashiensis the anterolateral margin and postfrontal crest mayshow granulation Potamonautes didieri Rathbun 1904 possesses a more completerounded postfrontal crest and shorter more stout chelipeds (Bott 1955)

ACKNOWLEDGEMENTS

Financial assistance was kindly provided by the World Wildlife Fund - SouthAfrica the Foundation for Research Development and the University of ZululandThe KwaZulu-Natal Nature Conservation Services provided accommodation and

POTAMONAUTES LIVIDUS NOV 159

logistic support Liz Hoenson Peter Cook Mike Coke and Tyrone Ridgway arethanked for assistance in the eld and Michelle van der Merwe is thanked foraiding in the photography and drafting of gures The authors wish to thank ananonymous reviewer for comments on the manuscript

REFERENCES

BARNARD K H 1935 Scienti c results of the Vernay-Lang Kalahari expedition March toSeptember 1930 Crustacea Ann Transvaal Mus 16 481-492

mdash mdash 1950 Descriptive catalogue of South African decapod Crustacea (crabs and shrimps) AnnSouth African Mus 38 1-837

BOCK W J 1986 Species concepts speciation and macroevolution In K IWATSUKIP H RAVEN amp W J BOCK (eds) Modern aspects of species 31-57 (University of TokyoPress Tokyo)

BOTT R 1955 Die Suumlsswasserkrabben von Afrika (Crust Decap) und ihre StammesgeschichteAnn Mus R Congo Belge (C Zool) 1 (33) 209-352 pls 1-30

BRUTON M N 1980 An outline of the ecology of the Mgobezeleni lake system at Sodwana withemphasis on the mangrove community In M N BRUTON amp K H COOPER (eds) Studieson the ecology of Maputaland 408-426 (Rhodes University Grahamstown)

CUMBERLIDGE N 1986 Ventilation of the branchial chambers in the amphibious West Africanfreshwater crab Sudanonautes (Convexonautes) aubryi monodi (Balss 1929) (BrachyuraPotamonautidae)Hydrobiol 134 53-65

mdash mdash 1991 The respiratory system of Globonautes macropus (Rathbun 1898) a terrestrialfreshwater crab from Liberia (GecarcinucoideaGecarcinucidae)Crustaceana 61 (1) 69-80

DANIELS S R B A STEWART amp M J GIBBONS 1998a Potamonautes granularis sp nov(Brachyura Potamonautidae) a new cryptic species of river crab from the Olifants Riversystem South Africa Crustaceana 71 (8) 885-903

mdash mdash mdash mdash amp mdash mdash 1998b Genetic and morphometric variation in the potamonautid river crabPotamonautes parvispina (Decapoda Potamonautidae) from two Western Cape rivers SouthAfrica Journ nat Hist London 32 1245-1258

mdash mdash mdash mdash amp mdash mdash 1999 Genetic structure among populations of Potamonautes perlatus(Decapoda Potamonautidae) from the Olifants River system in the Western Cape SouthAfrica Journ Zool London 249 (2) 137-142

DIacuteAZ H amp G RODRIacuteGUEZ 1977 The branchial chamber in terrestrial crabs a comparative studyBiol Bull Woods Hole 153 485-504

GOUWS G B A STEWART amp M COKE 2000 Evidence for a new species of river crab(Decapoda Brachyura Potamonautidae) from the Drakensberg South Africa Journ CrustBiol 20 (4) 743-758

GREENAWAY P amp H H TAYLOR 1976 Aerial gas exchange in Australian arid-zone crabParathelphusa transversa Von Martens Nature London 262 711-713

HILGENDORF F 1898 Die Land- und Suumlsswasser-Dekapoden Ostafrikas Die Thierwelt DeutschOst-Afrikas 4 (7) 1-37

LENZ H 1912 Afrikanische Crustaceen aus schwedischen Sammlungen Ark Zool 7 (29) 1-10MARKERT C L amp I FAULHABER 1965 Lactate dehydrogenase isozyme patterns of sh Journ

exp Zool 159 319-332MAYR E 1963 Animal species and evolution i-xiv 1-797 (Harvard University Press Cambridge

Massachusetts)mdash mdash 1970 Populations species and evolution i-xv 1-453 (Harvard University Press Cambridge

Massachusetts)

POTAMONAUTES LIVIDUS NOV 139

Fig 1 Sampling localities in northeasternKwaZulu-Natal South Africa

140 G GOUWS B A STEWART amp P E REAVELL

frontal lobe and characteristic colouration Potamonautes sidneyi (form B) indi-viduals could be identi ed following the descriptions and illustrations of Barnard(1950) and Bott (1955) by the presence of a sharp postfrontal crest scabrosityof the epibranchial corners and broad limbs Individuals of the undescribed form(form A) were collected from a patch of swamp-forest dominated by Syzygiumcordatum Hochst (common waterberry) trees and characterized by spongy hy-dromorphic peat soil at the University of Zululand campus a similar forest alongthe Mdibi stream (an af uent of Lake Mzingazi) north of Richards Bay and aFicus trichopoda Bak and Barringtonia racemosa (L) Roxb dominated swamp-forest near the Mapelane Nature Reserve Populations of P sidneyi were sampledfrom marshy grassland near Dakaneni village outside Hluhluwe Game Reserveand the upper reaches of the Manzibomvu River within the Hluhluwe Game Re-serve Potamonautes sidneyi populations were also sampled from the University ofZululand campus and Mdibi swamp-forest where they occur sympatrically withthe undescribed form (form A) Crabs were killed by overnight freezing Unfor-tunately specimens of P sidneyi from the Mdibi swamp-forest were unsuitablefor genetic analysis as specimens were processed days after capture and proteindenaturation could not be avoided due to repeated freezing and thawing duringtransportation

Biochemical analysis mdash Muscle and digestive-gland tissue (hepatopancreas)were removed from each specimen by dissection Tissue samples were stored incryogenic tubes at iexcl80plusmnC until electrophoresis was ready to be performed Tissuewas homogenized in 001 M Tris buffer (pH 8) using a glass rod attached to avariable-speed electric motor The samples were centrifuged for ve minutes at12000 rpm prior to use Filter paper wicks (Whatmans 3) were dipped into thesupernatant and inserted into the horizontal 13 starch gel (Sigma Chemicals CoSt Louis Missouri USA)

Three electrophoretic buffer systems were used (A) a discontinuous Tris-citrate-borate-lithium hydroxide buffer with a gel buffer pH 87 and an electrodebuffer pH 80 (Ridgeway Sherburne amp Lewis 1970) (B) a continuous Tris-borate-EDTA buffer system at pH 86 (Markert amp Faulhaber 1965) and (C) a continuousTris-citrate buffer system at pH 69 (Whitt 1970) Gels were run inside a fridge(4plusmnC) for 4 hours at 40 mA These were then sliced horizontally into 3 or 4 slicesand the sites of enzymatic activity histochemically stained in a 2 agar overlay(Shaw amp Prasad 1970)

Of 24 isozyme loci originally screened 21 were reliably interpretable andincluded in the analyses (table I) A sample of Potamonautes depressus Krauss1843 from the Coleford Nature Reserve was included in each run as a referencepopulation to provide continuity in scoring across all populations For each locusthe most common allele of the Coleford population was assigned a value of 100

POTAMONAUTES LIVIDUS NOV 141

TABLE IEnzymes and buffer systems used to determine biochemical variation in six populations of Potamo-

nautes spp studied

Enzyme Abbreviation EC Number Buffer Tissue Loci

Arginine kinase ARK 2733 A m 1Diaphorase DIA 1622 A h 1Glucose-6-phosphateisomerase GPI 5319 A m 1Hexokinase HEX 2711 B m 1Isocitrate dehydrogenase IDH 11142 C m 2Lactate dehydrogenase LDH 11127 A m 1Malate dehydrogenase MDH 11137 C m 2Malic enzyme ME 11140 B m 1Mannose-phosphate isomerace MPI 5318 B m 1Peptidase (glycyl-leucine as substrate) GL 3411ndash B m 1Peptidase (leucyl-glycyl-glycylas substrate) LGG 3411ndash A h 3Peptidase (leucyl-tyrosineas substrate) LT 3411ndash A B m h 2Peptidase (phenylamine-prolineas substrate) PHP 3411ndash B h 1Phosphoglucomutase PGM 5422 B m 2Phosphoglusonatedehydrogenase PGD 11144 C m 1

Buffer (A) discontinuous Tris-citrate-borate-lithium hydroxide buffer system (Ridgeway et al1970) (B) continuous Tris-borate-EDTA buffer system (Markert amp Faulhaber 1965) and (C) con-tinuous Tris-citrate buffer system (Whitt 1970) Tissue (m) muscle tissue and (h) hepatopancreas (digestive gland)

and all other alleles were scored relative to this value Where more than one locusstained for a particular enzyme the most anodally migrating one was labeled 1and the others labeled sequentially

All numerical analyses were performed using the BIOSYS-1 program (Swof-ford amp Selander 1981) Allele and genotype frequencies were calculated Geno-type frequencies were tested for deviation from frequencies expected under Hardy-Weinberg equilibrium by means of a Acirc2-goodness-of- t test Where more than twoalleles occurred at a locus the genotype frequencies were pooled Percentage poly-morphic loci were calculated for each population using no criterion (loci wereconsidered polymorphic if more than one allele was present at a locus) The meanexpected heterozygosity (H) was also calculated for each locus using unbiasedestimates (Nei 1978) The mean unbiased genetic identity (I ) and distance (D)were calculated for each pairwise comparison (Nei 1978) and a dendrogram con-structed using the measures of genetic identity and the UPGMA clustering algo-rithm (Sneath amp Sokal 1973)

Morphological analyses mdash Prior to dissection crabs were sexed and measuredusing digital Vernier-calipers and a portable computer The populations used forthe genetic analysis were supplemented with morphometric data from specimens

142 G GOUWS B A STEWART amp P E REAVELL

collected earlier at the above localities Seven carapace variables were recorded formorphometric analyses These were carapace length along the medial line (CL)carapace width at the widest part (CWW) posterior carapace width (CWP) thedistance between the postfrontal crest and the anterior carapace margin (PFCD)distance between the medial margins of the orbits (ED) distance between theexorbital teeth (CWA) and the carapace height (CH)

Data were log transformed (common logarithms) prior to analysis All statisticalanalyses were performed using the Statistica Version 51 program (StatSoft Inc1996) Morphological variation between the two forms was determined by meansof a stepwise discriminant function analysis using seven carapace variablesClassi cation functions were calculated using the jackknife procedure ensuringan unbiased classi cation function for determining group assignment Individualswere then reassigned to a group based on the highest a posteriori probability Afrequency histogram of individual canonical variable scores calculated from thediscriminant function analysis was plotted to reveal discrimination between thetwo forms Linear regression analyses were used to test for variation within speci cvariables between the two forms

Gonopods and mouthparts were removed and examined qualitatively using aLeitz stereoscopic dissection microscope and illustrated using a camera lucida orphotographed using a Wild MPS45 camera unit

RESULTS

Biochemical analysis mdash Of the 21 reliably scorable loci nine (ARK LT-1ME LDH MPI PGD DIA LGG-1 and LGG-3) were monomorphic across allpopulations analysed Twelve loci were polymorphic (table II) The LT-2 locus wasthe only locus polymorphic in each population The total number of alleles rangedfrom two in HEX MDH-1 IDH-1 GL PGM-2 PHP-2 and LGG-2 to ve in GPIWithin populations the maximum number of alleles was four found in GPI in theManzibomvu population

Out of thirty cases of polymorphism for all enzyme loci and populations three(10) were shown to deviate from genotype frequencies expected under Hardy-Weinberg equilibrium The LT-2 locus in the University of Zululand A population(Acirc2 D 9468 df D 3 P D 0024) the PHP locus in the Mdibi population(Acirc2 D 7037 df D 1 P D 0008) and the PGM-2 locus in the Dakanenipopulation (Acirc2 D 250 df D 1 P D 0000) were out of equilibrium due toa de cit of heterozygotes carrying the rare allele All other loci conformed toHardy-Weinberg expectations thus supporting a purely genetic interpretation ofthe polymorphisms observed

POTAMONAUTES LIVIDUS NOV 143

TABLE IIDistribution of allele frequencies at nine polymorphic loci in six populations of Potamonautes spp

studied N D sample size refer to table I for enzyme abbreviations

Population

Locus Zululand A Mdibi Mapelane Zululand B Dakaneni Manzibomvu

IDH-2N 41 24 25 13 25 13120 0012 0729 0380 0000 0000 000080 0988 0229 0000 1000 1000 100045 0000 0043 0620 0000 0000 0000

GPIN 56 26 25 13 25 13165 0045 0000 0000 0000 0000 0000150 0000 0000 0000 0000 0000 0038100 0000 0000 0000 0000 0000 003840 0938 1000 1000 0962 0880 0846

iexcl80 0018 0000 0000 0038 0120 0077

HEXN 41 26 25 13 25 13100 1000 1000 1000 0000 0000 000095 0000 0000 0000 1000 1000 1000

MDH-1N 41 26 25 13 25 13100 0988 1000 1000 1000 1000 100090 0012 0000 0000 0000 0000 0000

MDH-2N 41 26 25 13 25 13100 1000 1000 1000 0962 0960 100075 0000 0000 0000 0000 0040 000065 0000 0000 0000 0038 0000 0000

IDH-1N 41 26 25 13 23 7150 0000 0000 0000 1000 0891 0929135 1000 1000 1000 0000 0109 0071

LT-2N 41 26 25 13 25 13250 0049 0019 0020 0000 0000 0000100 0854 0885 0840 0923 0980 0769

0 0098 0096 0140 0077 0020 0231

PGM-1N 52 26 25 13 25 13110 0365 0000 0000 0000 0000 0000100 0212 0000 0000 0038 0140 003890 0423 1000 1000 0923 0800 096275 0000 0000 0000 0038 0060 0000

(continued overleaf)

144 G GOUWS B A STEWART amp P E REAVELL

TABLE II(Continued)

Population

Locus Zululand A Mdibi Mapelane Zululand B Dakaneni Manzibomvu

GLN 41 26 25 13 25 1390 1000 0962 1000 1000 1000 100075 0000 0038 0000 0000 0000 0000

PGM-2N 56 26 25 13 25 13100 1000 1000 1000 0000 0040 000075 0000 0000 0000 1000 0960 1000

PHPN 41 26 25 13 25 13105 1000 0808 1000 1000 1000 100090 0000 0192 0000 0000 0000 0000

LGG-2N 41 26 25 13 24 13100 0854 0942 1000 0846 0979 069290 0146 0058 0000 0154 0021 0308

Genetic variability was low in all populations The percentage polymorphicloci (no criterion) ranged from 95 to 333 in the Mapelane and Dakanenipopulations respectively The mean unbiased expected heterozygosity varied from0034 (in the University of Zululand B population) to 0063 (in the Universityof Zululand A and Manzibomvu populations) The mean number of alleles perlocus ranged from 11 (in the Mapelane population) to 14 (in the Dakaneni andUniversity of Zululand A populations)

The dendrogram constructed based on the genetic identity values obtained bypairwise comparison of populations (table III) clearly distinguished two clusters( g 2) The group representing the form A populations clearly separated from thegroup representing the form B (Potamonautes sidneyi) populations at a geneticidentity value of I D 0829 D D 0187 Three loci contributed signi cantly tothis separation one of them diagnostically The HEX locus showed a xed alleledifference between the individuals of the two forms with the form A individualsbeing xed for the allele HEX100 and the form B (P sidneyi) individuals xed forthe HEX95 allele Strong heterogeneity was observed between the populations ofthe two forms at the IDH-1 and PGM-2 loci With the exception of one individualin the Dakaneni population having a homozygote with the PGM-2100 allele form Aand form B were characterized by the xation of alleles PGM-2100 and PGM-275

POTAMONAUTES LIVIDUS NOV 145

TABLE IIICoef cient matrix of Neirsquos (1978) unbiased genetic identity (above diagonal) and unbiased geneticdistance (below diagonal) for pairwise comparisons of the six populations of Potamonautes studied

Population

Zululand A Mdibi Mapelane Zululand B Dakaneni Manzibomvu

Zululand A currencurrencurrencurrencurren 0958 0949 0840 0855 0842

Mdibi 0043 currencurrencurrencurrencurren 0986 0821 0832 0822

Mapelane 0052 0014 currencurrencurrencurrencurren 0813 0825 0814

Zululand B 0174 0197 0206 currencurrencurrencurrencurren 0998 0999

Dakaneni 0157 0184 0193 0002 currencurrencurrencurrencurren 0994

Manzibomvu 0172 0196 0206 0001 0006 currencurrencurrencurrencurren

Fig 2 UPGMA dendrogram constructed from the matrix of Neirsquos (1978) unbiased genetic identi-ties (I ) using allozyme data from 21 loci

respectively Identity-values for within form comparisons varied from 0949 to0986 (D D 0014 to 0052) and 0994 to 0999 (D D 0001 to 0006) for form Aand form B respectively

Morphometric analysis mdash Individuals from the form A populations couldeasily be distinguished from the form B (P sidneyi) individuals by the possessionof a much more vaulted carapace in ated chelipeds a postfrontal crest whichdiminishes medially and the characteristic silver-blue carapace sheen and brightorange to red chelipeds and pereopods Mature form B (P sidneyi) individualsfrequently attained a larger size class (with CL being representative of size) thandid the mature form A individuals

146 G GOUWS B A STEWART amp P E REAVELL

Three carapace variables (ED CH and CWP) contributed signi cantly to thediscrimination between the two forms in the discriminant function analysis Thehistogram plot of observed canonical variable scores ( g 3) clearly separates thetwo forms with the canonical variable means of the form A and form B individualscalculated at iexcl0996 and 1965 respectively The classi cation function (the linearfunction of variables which best discriminates the individuals of one group fromthe other speci ed groupings) was calculated for individuals of each form Theclassi cation function of the form A group was

Y D 306704 (Log CWP) iexcl 26103 (Log ED) iexcl 228513 (Log CH) iexcl 64156

and of the form B (P sidneyi) group

Y D 35097 (Log ED) iexcl 315543 (Log CH) C 347231 (Log CWP) iexcl 88367

Using the classi cation functions individuals were reassigned to groups basedon highest a posteriori probabilities Of the form A individuals 9437 (134of 142) were correctly classi ed with eight individuals being reassigned to theform B group Of the form B individuals 8889 were correctly reassigned to theP sidneyi group with eight of the 72 individuals being reassigned to the form Agroup

Fig 3 Histogram of scores for specimens of Potamonautes lividus sp nov (form A) and P sidneyiRathbun 1904 (form B) along the canonical variable calculated from a discriminant function

analysis using seven carapace variables

POTAMONAUTES LIVIDUS NOV 147

Comparison of regressions of the most discriminating variables between the twoforms regressed over CL in turn also showed signi cant differences between thetwo forms CH regressed over CL showed highly signi cant differences betweenthe two forms (SS D 0011 df D 1 F D 31266 P lt 0001) as did ED(SS D 0011 df D 1 F D 8333 P lt 0005) and CWP (SS D 0006 df D 1F D 8136 P lt 0005) These represent the most discriminating variables andtheir regressions are represented graphically ( g 4a b c) PFCD (SS D 0199df D 1 F D 52671 P lt 0001) CWW (SS D 0003 df D 1 F D 30963P lt 0001) and CWA (SS D 0001 df D 1 F D 6182 P lt 002) also showedthat there were signi cant differences between the two forms but the discriminantfunction analysis showed them to be redundant in constructing the model

Qualitative analysis mdash Examination of gonopods and mouthparts revealed onlyslight differences in gonopod morphology The terminal segment of gonopod 1of the undescribed form was relatively short and triangular whereas the terminalsegment of gonopod 1 of P sidneyi appears to be substantially longer and moreslender Although the terminal segment is bent away from the medial line in bothforms the terminal segment in P sidneyi possesses a lobe or ange that extendsinwards giving the terminal segment an S-shaped appearance The gonopods andmandibular palps of the two forms are illustrated in g 5

DISCUSSION

The data presented above clearly indicate that the two forms of freshwatercrabs from KwaZulu-Natal are distinct The form A specimens are smaller with amore vaulted carapace that is relatively narrower posteriorly and that possessesa relatively narrower frontal lobe (ED) than that of the Potamonautes sidneyiindividuals

Not only are the two forms clearly distinct both biochemically and morpho-logically but strong evidence suggests that they are reproductively isolated Thepresence of a diagnostic locus HEX xed for alternate alleles in the sympatricpopulation of the two forms indicates that a lack of gene ow and thus repro-ductive isolation exist between the two forms This allows for species recognitionunder the Biological Species Concept (Mayr 1970) under which species are de- ned as ldquogroups of actually or potentially interbreeding populations which arereproductively isolated from other such groupsrdquo (Mayr 1963 19) or ldquogeneticallyisolated (in nature) from other such groupsrdquo (Bock 1986 33) In his model of al-lopatric speciation Bock (1986) suggested that newly evolved species in sympatrywould exert mutually selective demands on each other by means of reproductive

148 G GOUWS B A STEWART amp P E REAVELL

Fig 4 Comparisons of the regressions of (A) Log CH (carapace height) over Log CL (carapacelength) (B) Log ED (eye distance) over Log CL and (C) Log CWP (posterior carapace width) overLog CL between form A (Potamonautes lividus sp nov) and form B (P sidneyi Rathbun 1904) All

differences are signi cant (at the P lt 0005 level)

POTAMONAUTES LIVIDUS NOV 149

Fig 5 A-E form A (Potamonautes lividus sp nov composite of male holotype SAM A43540and unaccessioned material) A carapace outline B left mandibular palp anterior view C leftmandibular palp posterior view D left gonopod 1 anterior view and E left gonopod 1 posteriorview F-J form B (Potamonautes sidneyi Rathbun 1904 unaccessioned specimen) F carapaceoutline G left mandibular palp anterior view H left mandibular palp posterior view I left

gonopod 1 anterior view J left gonopod 1 posterior view

150 G GOUWS B A STEWART amp P E REAVELL

interference and ecological competition This would lead to a divergence of mor-phological and behavioural aspects of feeding reproduction and other ecologicalfeatures The different gonopod morphologies of the two forms may re ect this

The three form A populations clustered separately from the three P sidneyipopulations at a I -value of 0829 Stewart (1997a) calculated the separationI -value between P parvispina Stewart 1997 and P perlatus H Milne Edwards1837 to be 068 An I -value of 066 separated both P perlatus and P brinckiBott 1960 in the Western Cape (Stewart 1997b) and P unispinus Stewart ampCook 1998 and P sidneyi in Mpumalanga (Stewart amp Cook 1998) An I -valueof 0599 was obtained separating P clarus Gouws Stewart amp Coke 2000 andP depressus (Gouws et al 2000) The only species in the genus delineated using ahigher I -value was P granularis Daniels Stewart amp Gibbons 1998 which wasseparated from P perlatus in the Olifants River at a I -value of 088 (Danielset al 1998a 1999) Although slightly higher than most interspeci c values inthe genus the value obtained in this study nevertheless falls within the range (035to 085) speci ed by Thorpe (1982) to indicate congeneric species differencesAllopatric populations showing I -values of less than 085 are unlikely to beconspeci c (Thorpe amp Soleacute-Cava 1994) With the exception of two cases allpairwise comparisons between allopatric populations of the two forms yieldedI -values less than 085

Identity-values were high for comparisons within both the form A (0949 to0986) and P sidneyi (0994 to 0999) groups Intraspeci c I -values are generallyhigh in the genus Potamonautes and disjunct populations within a species tendto be genetically undifferentiated Intraspeci c I -values obtained in six studies(Stewart 1997a b Stewart amp Cook 1998 Daniels et al 1998b 1999) involvingsix Potamonautes species varied from 0902 to 1000 (D D 0000 to 0103)An intraspeci c I -value of 075 was obtained in a comparison of two groups ofP brincki populations across the Cape Peninsula and Cape Flats However thismost probably indicates a species difference and requires further investigation(Stewart 1997b) Given the high intraspeci c I -values characteristic of the genusand those obtained for comparisons within each form the I -value obtainedfor the comparison between the two forms most likely represents a speciesdifference

Bock (1986) also de ned a species as possessing a set of three distinctcharacteristics genetic unity reproductive unity and ecological unity Biochemicaldata provide support for compliance with the rst two criteria for both formsWhile no empirical evidence is as yet available con rming the third factor adegree of macro- and microhabitat segregation and thus ecological segregationis evident between the two forms Potamonautes sidneyi is widespread acrossthe province (Stewart et al 1995) while the other form appears to have a

POTAMONAUTES LIVIDUS NOV 151

more limited distribution in northeastern KwaZulu-Natal restricted to patches ofswamp forest with particular oral assemblages The swamp forests are oftencharacterized by Barringtonia racemosa Syzygium cordatum Ficus trichopodaHibiscus tiliaceus L Rauvola caffra Sond Voacanga thouarsii Roem amp SchultRaphia australis Oberm amp Strey and Podocarpus falcatus (Thunb) R Br exMirb with the fern Stenochlaena tenuifolia (Desv) T Moore often present in theunderstorey (Bruton 1980 Moll 1980) Within the swamp forests the sympatricpopulations appear to show a degree of microhabitat segregation Observationssuggest that P sidneyi has a closer association with water as individuals were nevercollected great distances away from seepage pools and channels owing throughthe forest Conversely individuals of the swamp-forest form were most oftencollected farther from water and their burrows were often among the vegetationObservations suggest that this form is more terrestrial Individuals were noticedto move to higher elevations when the water table rose through the hydromorphicpeat soil ooding their burrows and the surface and they were also more active oncloudy overcast days Evidence of terrestrial adaptation is most likely to be foundin the structure and histology of the organs and tissues involved in respirationfactors such as branchial chamber shape and volume gill structure and formulaand the structure and vascularization of the branchiostegite lining are knownto re ect changes brought upon by the constraints of the terrestrial environment(Greenaway amp Taylor 1976 Diacuteaz amp Rodriacuteguez 1977 Taylor amp Greenaway1979 Cumberlidge 1986 1991 Takeda et al 1996) Although the availabilityof material prohibited the investigation of this aspect future research may prove tobe fruitful and highlight a greater distinction between the two forms

Studies on terrestrial adaptation supplemented by behavioural data that couldillustrate microhabitat and ecological segregation would quantify further thedegree of differentiation between the two forms However two independent datasets biochemical and morphological present strong evidence for the speci c statusof the swamp-forest form

TAXONOMY

Potamonautes lividus sp nov ( gs 6-7)

Material examined mdash Holotype South African Museum (SAM) A43540 one male CL D255 mm Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws andL Hoenson Allotype SAM A43541 one female CL D 245 mm Ficus and Barringtonia swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S 32plusmn2401800E)coll 27 January 1997 by B A Stewart G Gouws and L Hoenson Other material SAM A43542two males Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws

152 G GOUWS B A STEWART amp P E REAVELL

and L Hoenson SAM A43543 one female Lake Nhlabane north of Richards Bay (28plusmn3800500S32plusmn1601700E) coll 27 April 1993 by the University of Zululand Zoology Department SAMA43544 three males one female Mdibi swamp forest along Mdibi stream 8 km north of RichardsBay (28plusmn4202400S 32plusmn0902600E) coll 26 January 1997 by B A Stewart P A Cook M CokeP E Reavell G Gouws and L Hoenson SAM A43545 one male one female Syzygium forestUniversity of Zululand campus (28plusmn5102500S 31plusmn5100200E) coll 24 January 1997 by B A StewartP A Cook P E Reavell G Gouws and L Hoenson SAM A43546 two males two femalesUniversity of Zululand stream owing through campus (28plusmn550S 31plusmn410E) coll 10 September 1995by P E Reavell SAM A41313 one male one female swamp forest Empangeni (28plusmn5102500S31plusmn5100200E) coll 2 August 1994 by M Coke SAM A41155 one male University of ZululandSyzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S 31plusmn450E) coll 10 December1988 by P E Reavell SAM A41153 three males smaller holes in hydromorphic soil Syzygiumcordatum swamp forest University of Zululand (28plusmn450S 31plusmn450E) coll 20 March 1994 byP E Reavell SAM A41156 one female Syzygium cordatum swamp forest University of Zululand(28plusmn450S 31plusmn450E) coll 18 May 1992 by P E Reavell SAM A41154 one male one femaleUniversity of Zululand Syzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S31plusmn450E) coll 10 May 1990 by P E Reavell SAM A43547 two males one female swamp forestUniversity of Zululand (28plusmn450S 31plusmn450E) coll 1 April 1994 by P E Reavell SAM A43548one male one female Syzygium and Bridelia dominated swamp forest University of Zululand(28plusmn5102500S 31plusmn5100200E) coll 7 October 1996 by P E Reavell SAM A43549 one female Mdibiswamp forest Lake Msingazi catchment area north of Richards Bay (28plusmn420S 32plusmn090E) coll5 December 1996 by P E Reavell Albany Museum mdash GEN910 one female Mpolozi swampsMapelane (28plusmn2601300S 32plusmn2402500E) coll 13 February 1991 Albany Museum mdash GEN965 twomales ve females NrsquoKoninga Valley Richards Bay (28plusmn450S 32plusmn030E) coll 7 April 1988

Other material mdash The following specimens included in the collections of the South AfricanMuseum warrant further investigation as although they bear some resemblance to the speciesdescribed below their identi cation is uncertain SAM A41276 one male one female Mbonenidam Mkuze Game Reserve (27plusmn3705700S 32plusmn1504500E) coll 28 October 1994 by M Coke SAMA41299 two males Nxwala stream Mkuze Game Reserve (27plusmn4302300S 32plusmn1601000E) coll 10November 1994 by O Bourquin SAM A41277 one male Rainpool south of entrance False BayPark (28plusmn0000100S 32plusmn2102100E) coll 26 October 1994 by M Coke SAM A41300 two malesKangela rainpoolN2 near Mtubatuba (28plusmn2200000S 32plusmn1103600E) coll 25 October 1994 by M Cokeand SAM A41211 one male Ntambanana (Ntrabanana) Zululand coll by H H Curson

Type locality mdash South Africa KwaZulu-Natal Barringtonia and Ficus swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S32plusmn2401800E)

Distribution mdash At present known only from the swamp forests (characterizedby Barringtonia racemosa Syzygium cordatum and Ficus trichopoda vegetationand spongy hydromorphic peat-soil) in the vicinity of Richards Bay Empangeniand the Mapelane Nature Reserve It is probable that the distribution of the speciesmay extend into low-lying areas to the east of the Drakensberg escarpment in theprovince of Mpumalanga and into Mozambique

Etymology mdash From the Latin ldquolividusrdquo meaning ldquobluerdquo or ldquolight bluerdquoreferring to the characteristic silver-blue sheen of the carapace The epitheton isan adjective agreeing in gender with the (masculine) generic name

POTAMONAUTES LIVIDUS NOV 153

Fig 6 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A wholeanimal dorsal aspect B whole animal ventral aspect C cephalothorax frontal aspect

Diagnosis mdash Carapace distinctly vaulted and relatively narrow posteriorlyEpibranchial teeth absent and anterolateral margin of the carapace smooth Post-frontal crest indistinct medially with frontal lobe projecting downwards Cara-pace characteristically orange to red with silver-blue sheen Chelipeds and limbs

154 G GOUWS B A STEWART amp P E REAVELL

bright orange to red with lighter cheliped and dactyl tips Chela in ated and highlyarched

Description of male holotype mdash Size Measurements of the holotype and theranges of other specimens are given in table IV

Carapace ( gs 6A C 7A) Carapace and limbs characteristically orange tored with the carapace possessing a silver-blue sheen when alive Preserved spec-imens (70 ethanol) appear less orange and the carapace retains a blue-greycolour Cephalothorax ovoid distinctly vaulted branchial region highly convex( g 6A C) maximum height and width at anterior third (ratio CHCL D 065CWWCL D 145) Anterior margin straight Urogastric grooves moderately wellde ned Cardiac grooves shallow and poorly de ned Carapace otherwise smoothPostfrontal crest smooth curves forward medially Postfrontal crest diminishesabove inner orbit margins though well de ned immediately lateral to forked mid-point groove by means of two indentations anterior to crest indicating epigas-tric lobes Exorbital teeth moderately sharp but small Epibranchial teeth ab-sent Anterolateral margin posterior to postfrontal crest smooth margin curvingin over carapace in branchial region though indistinctly Each ank has a longitu-dinal groove dividing the subhepatic from the pterygostomial region with verticalgroove running from longitudinal groove joining anterolateral margin between ex-orbital tooth and postfrontal crest

Sternites ( gs 6B 7B) Sternites 1 and 2 fused no suture visible First suture(sternal groove) between sternites 2 and 3 complete Second sternal groove

TABLE IVPotamonautes lividus sp nov wet weight (in g) and measurements (in mm) for the male holotype

and ranges for other individuals examined (maximum of 77 males and 70 females)

Variable Abbreviation Holotype Males Females

Wet weight WW 242 05-214 07-183Carapace length CL 255 84-247 89-276Carapace widest width CWW 370 114-360 118-373Carapace posterior width CWP 281 90-269 86-306Distance between postfrontal crest

and anterior margin PFCD 43 12-222 15-46Distance between orbits ED 114 42-119 43-123Distance between exorbital teeth CWA 259 96-254 96-262Carapace height CH 165 48-171 50-162Width of sixth abdominal segment AW6 75 28-74 31-240Major cheliped propodus length MCPL 427 71-402 76-291Major cheliped propodus height MCPH 198 28-189 28-142Pereopod 2 merus length P2ML 189 50-181 51-171Pereopod 2 merus width P2MW 58 19-56 18-59

POTAMONAUTES LIVIDUS NOV 155

Fig 7 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A carapaceoutline B thoracic sternum C right cheliped dactylus and propodus D left cheliped dactylusand propodus E left third maxilliped F left mandible and mandibular palp posterior view G leftmandibular palp posterior view H left mandibular palp anterior view I left gonopod 1 anteriorview J terminal segment left gonopod 1 anterior view K left gonopod 1 posterior view L leftgonopod 2 anterior view Scale lines represent 1 mm except for A-D where they represent 10 mm

156 G GOUWS B A STEWART amp P E REAVELL

between sternites 3 and 4 complete laterally becoming shallower mediallysloping sharply towards abdominopelvic region

Third maxillipeds ( gs 6C 7E) Filling entire buccal frame except for ovalefferent respiratory openings short agellum present on exopods ischium smoothwith moderately deep vertical groove

Mandibular palp ( g 7F G H) Mandibular palp with two segments terminalsegment undivided with a dense tuft of setae on posterior surface of angeof terminal segment Margins generally hirsute Subterminal segment slightlyenlarged distally

Chelipeds and walking legs ( gs 6A 7C D) Chelipeds markedly unequaldactylus of right cheliped strongly arched 163 times length of dactylus of leftcheliped Both dactyli armed with up to 20 cutting teeth three to four of whichare slightly larger and more prominent Propodus of right cheliped markedlyin ated 168 times longer and 20 times wider than that of left cheliped Pollexpossesses 20 cutting teeth four to ve of which are more prominent Carpi ofboth chelipeds possess one prominent and three rudimentary teeth Margins ofmeri granulose small blunt spine on anterior surface no spine on anterior-inferiormargin Pereopods generally slender (pereopod 2 merus length width D 328 andpereopod 5 merus lengthwidth D 271) P3 longest P5 shortest ventral marginsof propodi and meri smooth dorsal margin with ne sharp bristles dactyli endingin sharp points with margins bearing a series of sharp spinelike bristles

Pleon ( gs 6B 7B) First ve segments broad and short last two segmentslonger terminal segment rounded at distal end

Pleopods ( g 7I J K) Pleopod 1 (gonopod 1) terminal segment short 025times length of subterminal segment terminal segment curves away from mid-line when viewed posteriorly widest at base ending in pointed tip Subterminalsegment of pleopod 1 tapers distally inner lateral margin slightly irregular outerlateral margin straighter both margins hirsute Posterior surface with twisting lon-gitudinal groove extending length of subterminal and terminal segment Groovenot visible on anterior surface Posterior surface and margins of groove hirsutePleopod 2 (gonopod 2) terminal segment lament-like 05 the length of subter-minal segment curving slightly towards medial line proximally curves away frommedial line distally ( g 7L) Subterminal segment widest at base tapering sharplyinwards at 04 of length forms narrow process supporting terminal segment

Variation mdash All individuals are characteristically dark orange to red witha silver-blue sheen to the carapace while the chelipeds vary in colour frombright orange-red to a lighter yellow-orange All individuals are characterized byhighly vaulted carapaces and downwardly projecting frontal lobes The postfrontalcrest which is most pronounced laterally (from directly above the orbits to theanterolateral margin) and incomplete medially is often more distinct in the smaller

POTAMONAUTES LIVIDUS NOV 157

individuals Chelipeds are not always typically arched enclosing a large ovoidspace as in the holotype Chelipeds of smaller individuals although in ated areless arched and often tight closing with the small cutting teeth more obviousChelipeds of females and small males in particular from the Mdibi and Universityof Zululand localities have propodi that are relatively high with in ated palmsand relatively short tightly closing chelae which project slightly downwardsHeterochely has been demonstrated in most Potamonautes-species occurring inSouth Africa (Siegfried 1972 Raubenheimer 1986 Stewart et al 1995 Stewart1997a b Stewart amp Cook 1998 Daniels et al 1998a Gouws et al 2000) Withinthe species 76 of the specimens were right-handed with 11 being left-handedand 13 being of equal or subequal (differing by less than one millimeter) sizeOf the males 79 were right-handed 8 left-handed and 13 equal or subequalFemales had 74 right-handedness 13 left-handedness and in 13 of caseschelipeds were equal or subequal The abdomen of mature females completelyoverlaps the coxae of the pereopods The smallest mature female had a CL of167 mm with the largest immature female having a CL of 159 indicating that thepubertal moult occurs approximately between the 14 mm and 18 mm size classes

Remarks mdash Potamonautes lividus sp nov can readily be distinguished from theten other species in the genus Potamonautes known to occur within South AfricaPotamonautes warreni Calman 1918 P dentatus P parvispina and P unispinusall bear a singular spine or a series of teeth on the anterolateral margins whereasP lividus sp nov is smooth Potamonautes perlatus P sidneyi and P granularisare all larger crabs with in ated arched carapaces with complete distinct post-frontal crests and scabrosity or granulation of the anterior margins orbits epi-branchial corners or postfrontal crests Potamonautes lividus sp nov has smoothcarapace margins and a incomplete postfrontal crest The terminal segment ofgonopod 1 in P lividus sp nov is relatively short and triangular and curves awayfrom the medial line when viewed posteriorly while that of P sidneyi is relativelylonger more slender and more S-shaped The postfrontal crest of P sidneyi mayjoin the anterolateral margin at a relatively sharp angle and form a pronouncedepibranchial corner along the anterolateral margin The anterolateral margin inP lividus sp nov is more rounded and the epibranchial corners slope down to-wards the anks Potamonautes granularis is chocolate brown with orange tips tothe chelipeds Potamonautes brincki is a smaller crab with a smoother carapacethough also chocolate to reddish-brown in colour with a nely granulated antero-lateral margin which does not curve in over the carapace in the branchial region(Stewart 1997b) Potamonautes depressus and P clarus both have rounded epi-branchial corners and smooth carapaces though these are relatively shallow andhave attened dorsal surfaces Both are characterized by long slender limbs Pota-monautes depressus is brown to green-brown in colour while P clarus is brightorange in colour

158 G GOUWS B A STEWART amp P E REAVELL

A number of species from further a eld bear a super cial resemblance toP lividus sp nov particularly with regard to carapace morphology though in mostcases they can be readily distinguished Potamonautes pilosus Hilgendorf 1898 isknown from East Africa and is a small crab with a CWW of less than 25 mmSpecimens possess a weak postfrontal crest which along with the anterolateralmargin can be granulated (Hilgendorf 1898 Bott 1955) Potamonautes neumanniHilgendorf 1898 is known from East Africa and has a characteristically vaultedcarapace without a complete distinct postfrontal crest (Hilgendorf 1898 Bott1955) The postfrontal crest is more distinct in P lividus particularly laterally andthe exorbital teeth are sharper and more de ned in P lividus than in P neumanniThe terminal segment of gonopod 1 is longer and more slender in P neumannithan in P lividus and curves distinctly outwards The subterminal segment ofgonopod 1 is wider at its apex in P neumanni than in P lividus Additionally thecarapace of preserved specimens of P neumanni is typically grey in colour whileliving specimens are violet in colour with bright olive-green limbs and chelipeds(Hilgendorf 1898) Potamonautes ballayi acristatus Bott 1955 has an incompletepostfrontal crest only present above the orbits and small and blunt exorbital teethThe major chela although highly arched and the minor chela are long and moreslender than those of P lividus sp nov The terminal segment of gonopod 1 ofP granviki Colosi 1924 is curved towards the medial line when viewed posteriorly(Bott 1955) The chelae of both P berardi berardi Audouin 1826 and P b ignestiiParisi 1923 are relatively short and high with stout downward-projecting ngersThe anterior margin of the frontal lobe of P b berardi shows a distinct invaginationand the anterolateral margin appears sharp and less rounded than in P lividus spnov while the postfrontal crest of P b ignestii is complete and has a fairly longmedial groove Potamonautes emini emini Hilgendorf 1892 are generally smallcrabs with a less in ated carapace and short stout chelipeds The subterminaland terminal segments of gonopod 1 are of more or less equal size (Bott 1955)Potamonautes e semilunaris Bott 1955 and P luashiensis Bott 1955 are alsosmall crabs (CWW lt 20 mm) with the postfrontal crest only visible laterally andin the case of P luashiensis the anterolateral margin and postfrontal crest mayshow granulation Potamonautes didieri Rathbun 1904 possesses a more completerounded postfrontal crest and shorter more stout chelipeds (Bott 1955)

ACKNOWLEDGEMENTS

Financial assistance was kindly provided by the World Wildlife Fund - SouthAfrica the Foundation for Research Development and the University of ZululandThe KwaZulu-Natal Nature Conservation Services provided accommodation and

POTAMONAUTES LIVIDUS NOV 159

logistic support Liz Hoenson Peter Cook Mike Coke and Tyrone Ridgway arethanked for assistance in the eld and Michelle van der Merwe is thanked foraiding in the photography and drafting of gures The authors wish to thank ananonymous reviewer for comments on the manuscript

REFERENCES

BARNARD K H 1935 Scienti c results of the Vernay-Lang Kalahari expedition March toSeptember 1930 Crustacea Ann Transvaal Mus 16 481-492

mdash mdash 1950 Descriptive catalogue of South African decapod Crustacea (crabs and shrimps) AnnSouth African Mus 38 1-837

BOCK W J 1986 Species concepts speciation and macroevolution In K IWATSUKIP H RAVEN amp W J BOCK (eds) Modern aspects of species 31-57 (University of TokyoPress Tokyo)

BOTT R 1955 Die Suumlsswasserkrabben von Afrika (Crust Decap) und ihre StammesgeschichteAnn Mus R Congo Belge (C Zool) 1 (33) 209-352 pls 1-30

BRUTON M N 1980 An outline of the ecology of the Mgobezeleni lake system at Sodwana withemphasis on the mangrove community In M N BRUTON amp K H COOPER (eds) Studieson the ecology of Maputaland 408-426 (Rhodes University Grahamstown)

CUMBERLIDGE N 1986 Ventilation of the branchial chambers in the amphibious West Africanfreshwater crab Sudanonautes (Convexonautes) aubryi monodi (Balss 1929) (BrachyuraPotamonautidae)Hydrobiol 134 53-65

mdash mdash 1991 The respiratory system of Globonautes macropus (Rathbun 1898) a terrestrialfreshwater crab from Liberia (GecarcinucoideaGecarcinucidae)Crustaceana 61 (1) 69-80

DANIELS S R B A STEWART amp M J GIBBONS 1998a Potamonautes granularis sp nov(Brachyura Potamonautidae) a new cryptic species of river crab from the Olifants Riversystem South Africa Crustaceana 71 (8) 885-903

mdash mdash mdash mdash amp mdash mdash 1998b Genetic and morphometric variation in the potamonautid river crabPotamonautes parvispina (Decapoda Potamonautidae) from two Western Cape rivers SouthAfrica Journ nat Hist London 32 1245-1258

mdash mdash mdash mdash amp mdash mdash 1999 Genetic structure among populations of Potamonautes perlatus(Decapoda Potamonautidae) from the Olifants River system in the Western Cape SouthAfrica Journ Zool London 249 (2) 137-142

DIacuteAZ H amp G RODRIacuteGUEZ 1977 The branchial chamber in terrestrial crabs a comparative studyBiol Bull Woods Hole 153 485-504

GOUWS G B A STEWART amp M COKE 2000 Evidence for a new species of river crab(Decapoda Brachyura Potamonautidae) from the Drakensberg South Africa Journ CrustBiol 20 (4) 743-758

GREENAWAY P amp H H TAYLOR 1976 Aerial gas exchange in Australian arid-zone crabParathelphusa transversa Von Martens Nature London 262 711-713

HILGENDORF F 1898 Die Land- und Suumlsswasser-Dekapoden Ostafrikas Die Thierwelt DeutschOst-Afrikas 4 (7) 1-37

LENZ H 1912 Afrikanische Crustaceen aus schwedischen Sammlungen Ark Zool 7 (29) 1-10MARKERT C L amp I FAULHABER 1965 Lactate dehydrogenase isozyme patterns of sh Journ

exp Zool 159 319-332MAYR E 1963 Animal species and evolution i-xiv 1-797 (Harvard University Press Cambridge

Massachusetts)mdash mdash 1970 Populations species and evolution i-xv 1-453 (Harvard University Press Cambridge

Massachusetts)

140 G GOUWS B A STEWART amp P E REAVELL

frontal lobe and characteristic colouration Potamonautes sidneyi (form B) indi-viduals could be identi ed following the descriptions and illustrations of Barnard(1950) and Bott (1955) by the presence of a sharp postfrontal crest scabrosityof the epibranchial corners and broad limbs Individuals of the undescribed form(form A) were collected from a patch of swamp-forest dominated by Syzygiumcordatum Hochst (common waterberry) trees and characterized by spongy hy-dromorphic peat soil at the University of Zululand campus a similar forest alongthe Mdibi stream (an af uent of Lake Mzingazi) north of Richards Bay and aFicus trichopoda Bak and Barringtonia racemosa (L) Roxb dominated swamp-forest near the Mapelane Nature Reserve Populations of P sidneyi were sampledfrom marshy grassland near Dakaneni village outside Hluhluwe Game Reserveand the upper reaches of the Manzibomvu River within the Hluhluwe Game Re-serve Potamonautes sidneyi populations were also sampled from the University ofZululand campus and Mdibi swamp-forest where they occur sympatrically withthe undescribed form (form A) Crabs were killed by overnight freezing Unfor-tunately specimens of P sidneyi from the Mdibi swamp-forest were unsuitablefor genetic analysis as specimens were processed days after capture and proteindenaturation could not be avoided due to repeated freezing and thawing duringtransportation

Biochemical analysis mdash Muscle and digestive-gland tissue (hepatopancreas)were removed from each specimen by dissection Tissue samples were stored incryogenic tubes at iexcl80plusmnC until electrophoresis was ready to be performed Tissuewas homogenized in 001 M Tris buffer (pH 8) using a glass rod attached to avariable-speed electric motor The samples were centrifuged for ve minutes at12000 rpm prior to use Filter paper wicks (Whatmans 3) were dipped into thesupernatant and inserted into the horizontal 13 starch gel (Sigma Chemicals CoSt Louis Missouri USA)

Three electrophoretic buffer systems were used (A) a discontinuous Tris-citrate-borate-lithium hydroxide buffer with a gel buffer pH 87 and an electrodebuffer pH 80 (Ridgeway Sherburne amp Lewis 1970) (B) a continuous Tris-borate-EDTA buffer system at pH 86 (Markert amp Faulhaber 1965) and (C) a continuousTris-citrate buffer system at pH 69 (Whitt 1970) Gels were run inside a fridge(4plusmnC) for 4 hours at 40 mA These were then sliced horizontally into 3 or 4 slicesand the sites of enzymatic activity histochemically stained in a 2 agar overlay(Shaw amp Prasad 1970)

Of 24 isozyme loci originally screened 21 were reliably interpretable andincluded in the analyses (table I) A sample of Potamonautes depressus Krauss1843 from the Coleford Nature Reserve was included in each run as a referencepopulation to provide continuity in scoring across all populations For each locusthe most common allele of the Coleford population was assigned a value of 100

POTAMONAUTES LIVIDUS NOV 141

TABLE IEnzymes and buffer systems used to determine biochemical variation in six populations of Potamo-

nautes spp studied

Enzyme Abbreviation EC Number Buffer Tissue Loci

Arginine kinase ARK 2733 A m 1Diaphorase DIA 1622 A h 1Glucose-6-phosphateisomerase GPI 5319 A m 1Hexokinase HEX 2711 B m 1Isocitrate dehydrogenase IDH 11142 C m 2Lactate dehydrogenase LDH 11127 A m 1Malate dehydrogenase MDH 11137 C m 2Malic enzyme ME 11140 B m 1Mannose-phosphate isomerace MPI 5318 B m 1Peptidase (glycyl-leucine as substrate) GL 3411ndash B m 1Peptidase (leucyl-glycyl-glycylas substrate) LGG 3411ndash A h 3Peptidase (leucyl-tyrosineas substrate) LT 3411ndash A B m h 2Peptidase (phenylamine-prolineas substrate) PHP 3411ndash B h 1Phosphoglucomutase PGM 5422 B m 2Phosphoglusonatedehydrogenase PGD 11144 C m 1

Buffer (A) discontinuous Tris-citrate-borate-lithium hydroxide buffer system (Ridgeway et al1970) (B) continuous Tris-borate-EDTA buffer system (Markert amp Faulhaber 1965) and (C) con-tinuous Tris-citrate buffer system (Whitt 1970) Tissue (m) muscle tissue and (h) hepatopancreas (digestive gland)

and all other alleles were scored relative to this value Where more than one locusstained for a particular enzyme the most anodally migrating one was labeled 1and the others labeled sequentially

All numerical analyses were performed using the BIOSYS-1 program (Swof-ford amp Selander 1981) Allele and genotype frequencies were calculated Geno-type frequencies were tested for deviation from frequencies expected under Hardy-Weinberg equilibrium by means of a Acirc2-goodness-of- t test Where more than twoalleles occurred at a locus the genotype frequencies were pooled Percentage poly-morphic loci were calculated for each population using no criterion (loci wereconsidered polymorphic if more than one allele was present at a locus) The meanexpected heterozygosity (H) was also calculated for each locus using unbiasedestimates (Nei 1978) The mean unbiased genetic identity (I ) and distance (D)were calculated for each pairwise comparison (Nei 1978) and a dendrogram con-structed using the measures of genetic identity and the UPGMA clustering algo-rithm (Sneath amp Sokal 1973)

Morphological analyses mdash Prior to dissection crabs were sexed and measuredusing digital Vernier-calipers and a portable computer The populations used forthe genetic analysis were supplemented with morphometric data from specimens

142 G GOUWS B A STEWART amp P E REAVELL

collected earlier at the above localities Seven carapace variables were recorded formorphometric analyses These were carapace length along the medial line (CL)carapace width at the widest part (CWW) posterior carapace width (CWP) thedistance between the postfrontal crest and the anterior carapace margin (PFCD)distance between the medial margins of the orbits (ED) distance between theexorbital teeth (CWA) and the carapace height (CH)

Data were log transformed (common logarithms) prior to analysis All statisticalanalyses were performed using the Statistica Version 51 program (StatSoft Inc1996) Morphological variation between the two forms was determined by meansof a stepwise discriminant function analysis using seven carapace variablesClassi cation functions were calculated using the jackknife procedure ensuringan unbiased classi cation function for determining group assignment Individualswere then reassigned to a group based on the highest a posteriori probability Afrequency histogram of individual canonical variable scores calculated from thediscriminant function analysis was plotted to reveal discrimination between thetwo forms Linear regression analyses were used to test for variation within speci cvariables between the two forms

Gonopods and mouthparts were removed and examined qualitatively using aLeitz stereoscopic dissection microscope and illustrated using a camera lucida orphotographed using a Wild MPS45 camera unit

RESULTS

Biochemical analysis mdash Of the 21 reliably scorable loci nine (ARK LT-1ME LDH MPI PGD DIA LGG-1 and LGG-3) were monomorphic across allpopulations analysed Twelve loci were polymorphic (table II) The LT-2 locus wasthe only locus polymorphic in each population The total number of alleles rangedfrom two in HEX MDH-1 IDH-1 GL PGM-2 PHP-2 and LGG-2 to ve in GPIWithin populations the maximum number of alleles was four found in GPI in theManzibomvu population

Out of thirty cases of polymorphism for all enzyme loci and populations three(10) were shown to deviate from genotype frequencies expected under Hardy-Weinberg equilibrium The LT-2 locus in the University of Zululand A population(Acirc2 D 9468 df D 3 P D 0024) the PHP locus in the Mdibi population(Acirc2 D 7037 df D 1 P D 0008) and the PGM-2 locus in the Dakanenipopulation (Acirc2 D 250 df D 1 P D 0000) were out of equilibrium due toa de cit of heterozygotes carrying the rare allele All other loci conformed toHardy-Weinberg expectations thus supporting a purely genetic interpretation ofthe polymorphisms observed

POTAMONAUTES LIVIDUS NOV 143

TABLE IIDistribution of allele frequencies at nine polymorphic loci in six populations of Potamonautes spp

studied N D sample size refer to table I for enzyme abbreviations

Population

Locus Zululand A Mdibi Mapelane Zululand B Dakaneni Manzibomvu

IDH-2N 41 24 25 13 25 13120 0012 0729 0380 0000 0000 000080 0988 0229 0000 1000 1000 100045 0000 0043 0620 0000 0000 0000

GPIN 56 26 25 13 25 13165 0045 0000 0000 0000 0000 0000150 0000 0000 0000 0000 0000 0038100 0000 0000 0000 0000 0000 003840 0938 1000 1000 0962 0880 0846

iexcl80 0018 0000 0000 0038 0120 0077

HEXN 41 26 25 13 25 13100 1000 1000 1000 0000 0000 000095 0000 0000 0000 1000 1000 1000

MDH-1N 41 26 25 13 25 13100 0988 1000 1000 1000 1000 100090 0012 0000 0000 0000 0000 0000

MDH-2N 41 26 25 13 25 13100 1000 1000 1000 0962 0960 100075 0000 0000 0000 0000 0040 000065 0000 0000 0000 0038 0000 0000

IDH-1N 41 26 25 13 23 7150 0000 0000 0000 1000 0891 0929135 1000 1000 1000 0000 0109 0071

LT-2N 41 26 25 13 25 13250 0049 0019 0020 0000 0000 0000100 0854 0885 0840 0923 0980 0769

0 0098 0096 0140 0077 0020 0231

PGM-1N 52 26 25 13 25 13110 0365 0000 0000 0000 0000 0000100 0212 0000 0000 0038 0140 003890 0423 1000 1000 0923 0800 096275 0000 0000 0000 0038 0060 0000

(continued overleaf)

144 G GOUWS B A STEWART amp P E REAVELL

TABLE II(Continued)

Population

Locus Zululand A Mdibi Mapelane Zululand B Dakaneni Manzibomvu

GLN 41 26 25 13 25 1390 1000 0962 1000 1000 1000 100075 0000 0038 0000 0000 0000 0000

PGM-2N 56 26 25 13 25 13100 1000 1000 1000 0000 0040 000075 0000 0000 0000 1000 0960 1000

PHPN 41 26 25 13 25 13105 1000 0808 1000 1000 1000 100090 0000 0192 0000 0000 0000 0000

LGG-2N 41 26 25 13 24 13100 0854 0942 1000 0846 0979 069290 0146 0058 0000 0154 0021 0308

Genetic variability was low in all populations The percentage polymorphicloci (no criterion) ranged from 95 to 333 in the Mapelane and Dakanenipopulations respectively The mean unbiased expected heterozygosity varied from0034 (in the University of Zululand B population) to 0063 (in the Universityof Zululand A and Manzibomvu populations) The mean number of alleles perlocus ranged from 11 (in the Mapelane population) to 14 (in the Dakaneni andUniversity of Zululand A populations)

The dendrogram constructed based on the genetic identity values obtained bypairwise comparison of populations (table III) clearly distinguished two clusters( g 2) The group representing the form A populations clearly separated from thegroup representing the form B (Potamonautes sidneyi) populations at a geneticidentity value of I D 0829 D D 0187 Three loci contributed signi cantly tothis separation one of them diagnostically The HEX locus showed a xed alleledifference between the individuals of the two forms with the form A individualsbeing xed for the allele HEX100 and the form B (P sidneyi) individuals xed forthe HEX95 allele Strong heterogeneity was observed between the populations ofthe two forms at the IDH-1 and PGM-2 loci With the exception of one individualin the Dakaneni population having a homozygote with the PGM-2100 allele form Aand form B were characterized by the xation of alleles PGM-2100 and PGM-275

POTAMONAUTES LIVIDUS NOV 145

TABLE IIICoef cient matrix of Neirsquos (1978) unbiased genetic identity (above diagonal) and unbiased geneticdistance (below diagonal) for pairwise comparisons of the six populations of Potamonautes studied

Population

Zululand A Mdibi Mapelane Zululand B Dakaneni Manzibomvu

Zululand A currencurrencurrencurrencurren 0958 0949 0840 0855 0842

Mdibi 0043 currencurrencurrencurrencurren 0986 0821 0832 0822

Mapelane 0052 0014 currencurrencurrencurrencurren 0813 0825 0814

Zululand B 0174 0197 0206 currencurrencurrencurrencurren 0998 0999

Dakaneni 0157 0184 0193 0002 currencurrencurrencurrencurren 0994

Manzibomvu 0172 0196 0206 0001 0006 currencurrencurrencurrencurren

Fig 2 UPGMA dendrogram constructed from the matrix of Neirsquos (1978) unbiased genetic identi-ties (I ) using allozyme data from 21 loci

respectively Identity-values for within form comparisons varied from 0949 to0986 (D D 0014 to 0052) and 0994 to 0999 (D D 0001 to 0006) for form Aand form B respectively

Morphometric analysis mdash Individuals from the form A populations couldeasily be distinguished from the form B (P sidneyi) individuals by the possessionof a much more vaulted carapace in ated chelipeds a postfrontal crest whichdiminishes medially and the characteristic silver-blue carapace sheen and brightorange to red chelipeds and pereopods Mature form B (P sidneyi) individualsfrequently attained a larger size class (with CL being representative of size) thandid the mature form A individuals

146 G GOUWS B A STEWART amp P E REAVELL

Three carapace variables (ED CH and CWP) contributed signi cantly to thediscrimination between the two forms in the discriminant function analysis Thehistogram plot of observed canonical variable scores ( g 3) clearly separates thetwo forms with the canonical variable means of the form A and form B individualscalculated at iexcl0996 and 1965 respectively The classi cation function (the linearfunction of variables which best discriminates the individuals of one group fromthe other speci ed groupings) was calculated for individuals of each form Theclassi cation function of the form A group was

Y D 306704 (Log CWP) iexcl 26103 (Log ED) iexcl 228513 (Log CH) iexcl 64156

and of the form B (P sidneyi) group

Y D 35097 (Log ED) iexcl 315543 (Log CH) C 347231 (Log CWP) iexcl 88367

Using the classi cation functions individuals were reassigned to groups basedon highest a posteriori probabilities Of the form A individuals 9437 (134of 142) were correctly classi ed with eight individuals being reassigned to theform B group Of the form B individuals 8889 were correctly reassigned to theP sidneyi group with eight of the 72 individuals being reassigned to the form Agroup

Fig 3 Histogram of scores for specimens of Potamonautes lividus sp nov (form A) and P sidneyiRathbun 1904 (form B) along the canonical variable calculated from a discriminant function

analysis using seven carapace variables

POTAMONAUTES LIVIDUS NOV 147

Comparison of regressions of the most discriminating variables between the twoforms regressed over CL in turn also showed signi cant differences between thetwo forms CH regressed over CL showed highly signi cant differences betweenthe two forms (SS D 0011 df D 1 F D 31266 P lt 0001) as did ED(SS D 0011 df D 1 F D 8333 P lt 0005) and CWP (SS D 0006 df D 1F D 8136 P lt 0005) These represent the most discriminating variables andtheir regressions are represented graphically ( g 4a b c) PFCD (SS D 0199df D 1 F D 52671 P lt 0001) CWW (SS D 0003 df D 1 F D 30963P lt 0001) and CWA (SS D 0001 df D 1 F D 6182 P lt 002) also showedthat there were signi cant differences between the two forms but the discriminantfunction analysis showed them to be redundant in constructing the model

Qualitative analysis mdash Examination of gonopods and mouthparts revealed onlyslight differences in gonopod morphology The terminal segment of gonopod 1of the undescribed form was relatively short and triangular whereas the terminalsegment of gonopod 1 of P sidneyi appears to be substantially longer and moreslender Although the terminal segment is bent away from the medial line in bothforms the terminal segment in P sidneyi possesses a lobe or ange that extendsinwards giving the terminal segment an S-shaped appearance The gonopods andmandibular palps of the two forms are illustrated in g 5

DISCUSSION

The data presented above clearly indicate that the two forms of freshwatercrabs from KwaZulu-Natal are distinct The form A specimens are smaller with amore vaulted carapace that is relatively narrower posteriorly and that possessesa relatively narrower frontal lobe (ED) than that of the Potamonautes sidneyiindividuals

Not only are the two forms clearly distinct both biochemically and morpho-logically but strong evidence suggests that they are reproductively isolated Thepresence of a diagnostic locus HEX xed for alternate alleles in the sympatricpopulation of the two forms indicates that a lack of gene ow and thus repro-ductive isolation exist between the two forms This allows for species recognitionunder the Biological Species Concept (Mayr 1970) under which species are de- ned as ldquogroups of actually or potentially interbreeding populations which arereproductively isolated from other such groupsrdquo (Mayr 1963 19) or ldquogeneticallyisolated (in nature) from other such groupsrdquo (Bock 1986 33) In his model of al-lopatric speciation Bock (1986) suggested that newly evolved species in sympatrywould exert mutually selective demands on each other by means of reproductive

148 G GOUWS B A STEWART amp P E REAVELL

Fig 4 Comparisons of the regressions of (A) Log CH (carapace height) over Log CL (carapacelength) (B) Log ED (eye distance) over Log CL and (C) Log CWP (posterior carapace width) overLog CL between form A (Potamonautes lividus sp nov) and form B (P sidneyi Rathbun 1904) All

differences are signi cant (at the P lt 0005 level)

POTAMONAUTES LIVIDUS NOV 149

Fig 5 A-E form A (Potamonautes lividus sp nov composite of male holotype SAM A43540and unaccessioned material) A carapace outline B left mandibular palp anterior view C leftmandibular palp posterior view D left gonopod 1 anterior view and E left gonopod 1 posteriorview F-J form B (Potamonautes sidneyi Rathbun 1904 unaccessioned specimen) F carapaceoutline G left mandibular palp anterior view H left mandibular palp posterior view I left

gonopod 1 anterior view J left gonopod 1 posterior view

150 G GOUWS B A STEWART amp P E REAVELL

interference and ecological competition This would lead to a divergence of mor-phological and behavioural aspects of feeding reproduction and other ecologicalfeatures The different gonopod morphologies of the two forms may re ect this

The three form A populations clustered separately from the three P sidneyipopulations at a I -value of 0829 Stewart (1997a) calculated the separationI -value between P parvispina Stewart 1997 and P perlatus H Milne Edwards1837 to be 068 An I -value of 066 separated both P perlatus and P brinckiBott 1960 in the Western Cape (Stewart 1997b) and P unispinus Stewart ampCook 1998 and P sidneyi in Mpumalanga (Stewart amp Cook 1998) An I -valueof 0599 was obtained separating P clarus Gouws Stewart amp Coke 2000 andP depressus (Gouws et al 2000) The only species in the genus delineated using ahigher I -value was P granularis Daniels Stewart amp Gibbons 1998 which wasseparated from P perlatus in the Olifants River at a I -value of 088 (Danielset al 1998a 1999) Although slightly higher than most interspeci c values inthe genus the value obtained in this study nevertheless falls within the range (035to 085) speci ed by Thorpe (1982) to indicate congeneric species differencesAllopatric populations showing I -values of less than 085 are unlikely to beconspeci c (Thorpe amp Soleacute-Cava 1994) With the exception of two cases allpairwise comparisons between allopatric populations of the two forms yieldedI -values less than 085

Identity-values were high for comparisons within both the form A (0949 to0986) and P sidneyi (0994 to 0999) groups Intraspeci c I -values are generallyhigh in the genus Potamonautes and disjunct populations within a species tendto be genetically undifferentiated Intraspeci c I -values obtained in six studies(Stewart 1997a b Stewart amp Cook 1998 Daniels et al 1998b 1999) involvingsix Potamonautes species varied from 0902 to 1000 (D D 0000 to 0103)An intraspeci c I -value of 075 was obtained in a comparison of two groups ofP brincki populations across the Cape Peninsula and Cape Flats However thismost probably indicates a species difference and requires further investigation(Stewart 1997b) Given the high intraspeci c I -values characteristic of the genusand those obtained for comparisons within each form the I -value obtainedfor the comparison between the two forms most likely represents a speciesdifference

Bock (1986) also de ned a species as possessing a set of three distinctcharacteristics genetic unity reproductive unity and ecological unity Biochemicaldata provide support for compliance with the rst two criteria for both formsWhile no empirical evidence is as yet available con rming the third factor adegree of macro- and microhabitat segregation and thus ecological segregationis evident between the two forms Potamonautes sidneyi is widespread acrossthe province (Stewart et al 1995) while the other form appears to have a

POTAMONAUTES LIVIDUS NOV 151

more limited distribution in northeastern KwaZulu-Natal restricted to patches ofswamp forest with particular oral assemblages The swamp forests are oftencharacterized by Barringtonia racemosa Syzygium cordatum Ficus trichopodaHibiscus tiliaceus L Rauvola caffra Sond Voacanga thouarsii Roem amp SchultRaphia australis Oberm amp Strey and Podocarpus falcatus (Thunb) R Br exMirb with the fern Stenochlaena tenuifolia (Desv) T Moore often present in theunderstorey (Bruton 1980 Moll 1980) Within the swamp forests the sympatricpopulations appear to show a degree of microhabitat segregation Observationssuggest that P sidneyi has a closer association with water as individuals were nevercollected great distances away from seepage pools and channels owing throughthe forest Conversely individuals of the swamp-forest form were most oftencollected farther from water and their burrows were often among the vegetationObservations suggest that this form is more terrestrial Individuals were noticedto move to higher elevations when the water table rose through the hydromorphicpeat soil ooding their burrows and the surface and they were also more active oncloudy overcast days Evidence of terrestrial adaptation is most likely to be foundin the structure and histology of the organs and tissues involved in respirationfactors such as branchial chamber shape and volume gill structure and formulaand the structure and vascularization of the branchiostegite lining are knownto re ect changes brought upon by the constraints of the terrestrial environment(Greenaway amp Taylor 1976 Diacuteaz amp Rodriacuteguez 1977 Taylor amp Greenaway1979 Cumberlidge 1986 1991 Takeda et al 1996) Although the availabilityof material prohibited the investigation of this aspect future research may prove tobe fruitful and highlight a greater distinction between the two forms

Studies on terrestrial adaptation supplemented by behavioural data that couldillustrate microhabitat and ecological segregation would quantify further thedegree of differentiation between the two forms However two independent datasets biochemical and morphological present strong evidence for the speci c statusof the swamp-forest form

TAXONOMY

Potamonautes lividus sp nov ( gs 6-7)

Material examined mdash Holotype South African Museum (SAM) A43540 one male CL D255 mm Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws andL Hoenson Allotype SAM A43541 one female CL D 245 mm Ficus and Barringtonia swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S 32plusmn2401800E)coll 27 January 1997 by B A Stewart G Gouws and L Hoenson Other material SAM A43542two males Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws

152 G GOUWS B A STEWART amp P E REAVELL

and L Hoenson SAM A43543 one female Lake Nhlabane north of Richards Bay (28plusmn3800500S32plusmn1601700E) coll 27 April 1993 by the University of Zululand Zoology Department SAMA43544 three males one female Mdibi swamp forest along Mdibi stream 8 km north of RichardsBay (28plusmn4202400S 32plusmn0902600E) coll 26 January 1997 by B A Stewart P A Cook M CokeP E Reavell G Gouws and L Hoenson SAM A43545 one male one female Syzygium forestUniversity of Zululand campus (28plusmn5102500S 31plusmn5100200E) coll 24 January 1997 by B A StewartP A Cook P E Reavell G Gouws and L Hoenson SAM A43546 two males two femalesUniversity of Zululand stream owing through campus (28plusmn550S 31plusmn410E) coll 10 September 1995by P E Reavell SAM A41313 one male one female swamp forest Empangeni (28plusmn5102500S31plusmn5100200E) coll 2 August 1994 by M Coke SAM A41155 one male University of ZululandSyzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S 31plusmn450E) coll 10 December1988 by P E Reavell SAM A41153 three males smaller holes in hydromorphic soil Syzygiumcordatum swamp forest University of Zululand (28plusmn450S 31plusmn450E) coll 20 March 1994 byP E Reavell SAM A41156 one female Syzygium cordatum swamp forest University of Zululand(28plusmn450S 31plusmn450E) coll 18 May 1992 by P E Reavell SAM A41154 one male one femaleUniversity of Zululand Syzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S31plusmn450E) coll 10 May 1990 by P E Reavell SAM A43547 two males one female swamp forestUniversity of Zululand (28plusmn450S 31plusmn450E) coll 1 April 1994 by P E Reavell SAM A43548one male one female Syzygium and Bridelia dominated swamp forest University of Zululand(28plusmn5102500S 31plusmn5100200E) coll 7 October 1996 by P E Reavell SAM A43549 one female Mdibiswamp forest Lake Msingazi catchment area north of Richards Bay (28plusmn420S 32plusmn090E) coll5 December 1996 by P E Reavell Albany Museum mdash GEN910 one female Mpolozi swampsMapelane (28plusmn2601300S 32plusmn2402500E) coll 13 February 1991 Albany Museum mdash GEN965 twomales ve females NrsquoKoninga Valley Richards Bay (28plusmn450S 32plusmn030E) coll 7 April 1988

Other material mdash The following specimens included in the collections of the South AfricanMuseum warrant further investigation as although they bear some resemblance to the speciesdescribed below their identi cation is uncertain SAM A41276 one male one female Mbonenidam Mkuze Game Reserve (27plusmn3705700S 32plusmn1504500E) coll 28 October 1994 by M Coke SAMA41299 two males Nxwala stream Mkuze Game Reserve (27plusmn4302300S 32plusmn1601000E) coll 10November 1994 by O Bourquin SAM A41277 one male Rainpool south of entrance False BayPark (28plusmn0000100S 32plusmn2102100E) coll 26 October 1994 by M Coke SAM A41300 two malesKangela rainpoolN2 near Mtubatuba (28plusmn2200000S 32plusmn1103600E) coll 25 October 1994 by M Cokeand SAM A41211 one male Ntambanana (Ntrabanana) Zululand coll by H H Curson

Type locality mdash South Africa KwaZulu-Natal Barringtonia and Ficus swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S32plusmn2401800E)

Distribution mdash At present known only from the swamp forests (characterizedby Barringtonia racemosa Syzygium cordatum and Ficus trichopoda vegetationand spongy hydromorphic peat-soil) in the vicinity of Richards Bay Empangeniand the Mapelane Nature Reserve It is probable that the distribution of the speciesmay extend into low-lying areas to the east of the Drakensberg escarpment in theprovince of Mpumalanga and into Mozambique

Etymology mdash From the Latin ldquolividusrdquo meaning ldquobluerdquo or ldquolight bluerdquoreferring to the characteristic silver-blue sheen of the carapace The epitheton isan adjective agreeing in gender with the (masculine) generic name

POTAMONAUTES LIVIDUS NOV 153

Fig 6 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A wholeanimal dorsal aspect B whole animal ventral aspect C cephalothorax frontal aspect

Diagnosis mdash Carapace distinctly vaulted and relatively narrow posteriorlyEpibranchial teeth absent and anterolateral margin of the carapace smooth Post-frontal crest indistinct medially with frontal lobe projecting downwards Cara-pace characteristically orange to red with silver-blue sheen Chelipeds and limbs

154 G GOUWS B A STEWART amp P E REAVELL

bright orange to red with lighter cheliped and dactyl tips Chela in ated and highlyarched

Description of male holotype mdash Size Measurements of the holotype and theranges of other specimens are given in table IV

Carapace ( gs 6A C 7A) Carapace and limbs characteristically orange tored with the carapace possessing a silver-blue sheen when alive Preserved spec-imens (70 ethanol) appear less orange and the carapace retains a blue-greycolour Cephalothorax ovoid distinctly vaulted branchial region highly convex( g 6A C) maximum height and width at anterior third (ratio CHCL D 065CWWCL D 145) Anterior margin straight Urogastric grooves moderately wellde ned Cardiac grooves shallow and poorly de ned Carapace otherwise smoothPostfrontal crest smooth curves forward medially Postfrontal crest diminishesabove inner orbit margins though well de ned immediately lateral to forked mid-point groove by means of two indentations anterior to crest indicating epigas-tric lobes Exorbital teeth moderately sharp but small Epibranchial teeth ab-sent Anterolateral margin posterior to postfrontal crest smooth margin curvingin over carapace in branchial region though indistinctly Each ank has a longitu-dinal groove dividing the subhepatic from the pterygostomial region with verticalgroove running from longitudinal groove joining anterolateral margin between ex-orbital tooth and postfrontal crest

Sternites ( gs 6B 7B) Sternites 1 and 2 fused no suture visible First suture(sternal groove) between sternites 2 and 3 complete Second sternal groove

TABLE IVPotamonautes lividus sp nov wet weight (in g) and measurements (in mm) for the male holotype

and ranges for other individuals examined (maximum of 77 males and 70 females)

Variable Abbreviation Holotype Males Females

Wet weight WW 242 05-214 07-183Carapace length CL 255 84-247 89-276Carapace widest width CWW 370 114-360 118-373Carapace posterior width CWP 281 90-269 86-306Distance between postfrontal crest

and anterior margin PFCD 43 12-222 15-46Distance between orbits ED 114 42-119 43-123Distance between exorbital teeth CWA 259 96-254 96-262Carapace height CH 165 48-171 50-162Width of sixth abdominal segment AW6 75 28-74 31-240Major cheliped propodus length MCPL 427 71-402 76-291Major cheliped propodus height MCPH 198 28-189 28-142Pereopod 2 merus length P2ML 189 50-181 51-171Pereopod 2 merus width P2MW 58 19-56 18-59

POTAMONAUTES LIVIDUS NOV 155

Fig 7 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A carapaceoutline B thoracic sternum C right cheliped dactylus and propodus D left cheliped dactylusand propodus E left third maxilliped F left mandible and mandibular palp posterior view G leftmandibular palp posterior view H left mandibular palp anterior view I left gonopod 1 anteriorview J terminal segment left gonopod 1 anterior view K left gonopod 1 posterior view L leftgonopod 2 anterior view Scale lines represent 1 mm except for A-D where they represent 10 mm

156 G GOUWS B A STEWART amp P E REAVELL

between sternites 3 and 4 complete laterally becoming shallower mediallysloping sharply towards abdominopelvic region

Third maxillipeds ( gs 6C 7E) Filling entire buccal frame except for ovalefferent respiratory openings short agellum present on exopods ischium smoothwith moderately deep vertical groove

Mandibular palp ( g 7F G H) Mandibular palp with two segments terminalsegment undivided with a dense tuft of setae on posterior surface of angeof terminal segment Margins generally hirsute Subterminal segment slightlyenlarged distally

Chelipeds and walking legs ( gs 6A 7C D) Chelipeds markedly unequaldactylus of right cheliped strongly arched 163 times length of dactylus of leftcheliped Both dactyli armed with up to 20 cutting teeth three to four of whichare slightly larger and more prominent Propodus of right cheliped markedlyin ated 168 times longer and 20 times wider than that of left cheliped Pollexpossesses 20 cutting teeth four to ve of which are more prominent Carpi ofboth chelipeds possess one prominent and three rudimentary teeth Margins ofmeri granulose small blunt spine on anterior surface no spine on anterior-inferiormargin Pereopods generally slender (pereopod 2 merus length width D 328 andpereopod 5 merus lengthwidth D 271) P3 longest P5 shortest ventral marginsof propodi and meri smooth dorsal margin with ne sharp bristles dactyli endingin sharp points with margins bearing a series of sharp spinelike bristles

Pleon ( gs 6B 7B) First ve segments broad and short last two segmentslonger terminal segment rounded at distal end

Pleopods ( g 7I J K) Pleopod 1 (gonopod 1) terminal segment short 025times length of subterminal segment terminal segment curves away from mid-line when viewed posteriorly widest at base ending in pointed tip Subterminalsegment of pleopod 1 tapers distally inner lateral margin slightly irregular outerlateral margin straighter both margins hirsute Posterior surface with twisting lon-gitudinal groove extending length of subterminal and terminal segment Groovenot visible on anterior surface Posterior surface and margins of groove hirsutePleopod 2 (gonopod 2) terminal segment lament-like 05 the length of subter-minal segment curving slightly towards medial line proximally curves away frommedial line distally ( g 7L) Subterminal segment widest at base tapering sharplyinwards at 04 of length forms narrow process supporting terminal segment

Variation mdash All individuals are characteristically dark orange to red witha silver-blue sheen to the carapace while the chelipeds vary in colour frombright orange-red to a lighter yellow-orange All individuals are characterized byhighly vaulted carapaces and downwardly projecting frontal lobes The postfrontalcrest which is most pronounced laterally (from directly above the orbits to theanterolateral margin) and incomplete medially is often more distinct in the smaller

POTAMONAUTES LIVIDUS NOV 157

individuals Chelipeds are not always typically arched enclosing a large ovoidspace as in the holotype Chelipeds of smaller individuals although in ated areless arched and often tight closing with the small cutting teeth more obviousChelipeds of females and small males in particular from the Mdibi and Universityof Zululand localities have propodi that are relatively high with in ated palmsand relatively short tightly closing chelae which project slightly downwardsHeterochely has been demonstrated in most Potamonautes-species occurring inSouth Africa (Siegfried 1972 Raubenheimer 1986 Stewart et al 1995 Stewart1997a b Stewart amp Cook 1998 Daniels et al 1998a Gouws et al 2000) Withinthe species 76 of the specimens were right-handed with 11 being left-handedand 13 being of equal or subequal (differing by less than one millimeter) sizeOf the males 79 were right-handed 8 left-handed and 13 equal or subequalFemales had 74 right-handedness 13 left-handedness and in 13 of caseschelipeds were equal or subequal The abdomen of mature females completelyoverlaps the coxae of the pereopods The smallest mature female had a CL of167 mm with the largest immature female having a CL of 159 indicating that thepubertal moult occurs approximately between the 14 mm and 18 mm size classes

Remarks mdash Potamonautes lividus sp nov can readily be distinguished from theten other species in the genus Potamonautes known to occur within South AfricaPotamonautes warreni Calman 1918 P dentatus P parvispina and P unispinusall bear a singular spine or a series of teeth on the anterolateral margins whereasP lividus sp nov is smooth Potamonautes perlatus P sidneyi and P granularisare all larger crabs with in ated arched carapaces with complete distinct post-frontal crests and scabrosity or granulation of the anterior margins orbits epi-branchial corners or postfrontal crests Potamonautes lividus sp nov has smoothcarapace margins and a incomplete postfrontal crest The terminal segment ofgonopod 1 in P lividus sp nov is relatively short and triangular and curves awayfrom the medial line when viewed posteriorly while that of P sidneyi is relativelylonger more slender and more S-shaped The postfrontal crest of P sidneyi mayjoin the anterolateral margin at a relatively sharp angle and form a pronouncedepibranchial corner along the anterolateral margin The anterolateral margin inP lividus sp nov is more rounded and the epibranchial corners slope down to-wards the anks Potamonautes granularis is chocolate brown with orange tips tothe chelipeds Potamonautes brincki is a smaller crab with a smoother carapacethough also chocolate to reddish-brown in colour with a nely granulated antero-lateral margin which does not curve in over the carapace in the branchial region(Stewart 1997b) Potamonautes depressus and P clarus both have rounded epi-branchial corners and smooth carapaces though these are relatively shallow andhave attened dorsal surfaces Both are characterized by long slender limbs Pota-monautes depressus is brown to green-brown in colour while P clarus is brightorange in colour

158 G GOUWS B A STEWART amp P E REAVELL

A number of species from further a eld bear a super cial resemblance toP lividus sp nov particularly with regard to carapace morphology though in mostcases they can be readily distinguished Potamonautes pilosus Hilgendorf 1898 isknown from East Africa and is a small crab with a CWW of less than 25 mmSpecimens possess a weak postfrontal crest which along with the anterolateralmargin can be granulated (Hilgendorf 1898 Bott 1955) Potamonautes neumanniHilgendorf 1898 is known from East Africa and has a characteristically vaultedcarapace without a complete distinct postfrontal crest (Hilgendorf 1898 Bott1955) The postfrontal crest is more distinct in P lividus particularly laterally andthe exorbital teeth are sharper and more de ned in P lividus than in P neumanniThe terminal segment of gonopod 1 is longer and more slender in P neumannithan in P lividus and curves distinctly outwards The subterminal segment ofgonopod 1 is wider at its apex in P neumanni than in P lividus Additionally thecarapace of preserved specimens of P neumanni is typically grey in colour whileliving specimens are violet in colour with bright olive-green limbs and chelipeds(Hilgendorf 1898) Potamonautes ballayi acristatus Bott 1955 has an incompletepostfrontal crest only present above the orbits and small and blunt exorbital teethThe major chela although highly arched and the minor chela are long and moreslender than those of P lividus sp nov The terminal segment of gonopod 1 ofP granviki Colosi 1924 is curved towards the medial line when viewed posteriorly(Bott 1955) The chelae of both P berardi berardi Audouin 1826 and P b ignestiiParisi 1923 are relatively short and high with stout downward-projecting ngersThe anterior margin of the frontal lobe of P b berardi shows a distinct invaginationand the anterolateral margin appears sharp and less rounded than in P lividus spnov while the postfrontal crest of P b ignestii is complete and has a fairly longmedial groove Potamonautes emini emini Hilgendorf 1892 are generally smallcrabs with a less in ated carapace and short stout chelipeds The subterminaland terminal segments of gonopod 1 are of more or less equal size (Bott 1955)Potamonautes e semilunaris Bott 1955 and P luashiensis Bott 1955 are alsosmall crabs (CWW lt 20 mm) with the postfrontal crest only visible laterally andin the case of P luashiensis the anterolateral margin and postfrontal crest mayshow granulation Potamonautes didieri Rathbun 1904 possesses a more completerounded postfrontal crest and shorter more stout chelipeds (Bott 1955)

ACKNOWLEDGEMENTS

Financial assistance was kindly provided by the World Wildlife Fund - SouthAfrica the Foundation for Research Development and the University of ZululandThe KwaZulu-Natal Nature Conservation Services provided accommodation and

POTAMONAUTES LIVIDUS NOV 159

logistic support Liz Hoenson Peter Cook Mike Coke and Tyrone Ridgway arethanked for assistance in the eld and Michelle van der Merwe is thanked foraiding in the photography and drafting of gures The authors wish to thank ananonymous reviewer for comments on the manuscript

REFERENCES

BARNARD K H 1935 Scienti c results of the Vernay-Lang Kalahari expedition March toSeptember 1930 Crustacea Ann Transvaal Mus 16 481-492

mdash mdash 1950 Descriptive catalogue of South African decapod Crustacea (crabs and shrimps) AnnSouth African Mus 38 1-837

BOCK W J 1986 Species concepts speciation and macroevolution In K IWATSUKIP H RAVEN amp W J BOCK (eds) Modern aspects of species 31-57 (University of TokyoPress Tokyo)

BOTT R 1955 Die Suumlsswasserkrabben von Afrika (Crust Decap) und ihre StammesgeschichteAnn Mus R Congo Belge (C Zool) 1 (33) 209-352 pls 1-30

BRUTON M N 1980 An outline of the ecology of the Mgobezeleni lake system at Sodwana withemphasis on the mangrove community In M N BRUTON amp K H COOPER (eds) Studieson the ecology of Maputaland 408-426 (Rhodes University Grahamstown)

CUMBERLIDGE N 1986 Ventilation of the branchial chambers in the amphibious West Africanfreshwater crab Sudanonautes (Convexonautes) aubryi monodi (Balss 1929) (BrachyuraPotamonautidae)Hydrobiol 134 53-65

mdash mdash 1991 The respiratory system of Globonautes macropus (Rathbun 1898) a terrestrialfreshwater crab from Liberia (GecarcinucoideaGecarcinucidae)Crustaceana 61 (1) 69-80

DANIELS S R B A STEWART amp M J GIBBONS 1998a Potamonautes granularis sp nov(Brachyura Potamonautidae) a new cryptic species of river crab from the Olifants Riversystem South Africa Crustaceana 71 (8) 885-903

mdash mdash mdash mdash amp mdash mdash 1998b Genetic and morphometric variation in the potamonautid river crabPotamonautes parvispina (Decapoda Potamonautidae) from two Western Cape rivers SouthAfrica Journ nat Hist London 32 1245-1258

mdash mdash mdash mdash amp mdash mdash 1999 Genetic structure among populations of Potamonautes perlatus(Decapoda Potamonautidae) from the Olifants River system in the Western Cape SouthAfrica Journ Zool London 249 (2) 137-142

DIacuteAZ H amp G RODRIacuteGUEZ 1977 The branchial chamber in terrestrial crabs a comparative studyBiol Bull Woods Hole 153 485-504

GOUWS G B A STEWART amp M COKE 2000 Evidence for a new species of river crab(Decapoda Brachyura Potamonautidae) from the Drakensberg South Africa Journ CrustBiol 20 (4) 743-758

GREENAWAY P amp H H TAYLOR 1976 Aerial gas exchange in Australian arid-zone crabParathelphusa transversa Von Martens Nature London 262 711-713

HILGENDORF F 1898 Die Land- und Suumlsswasser-Dekapoden Ostafrikas Die Thierwelt DeutschOst-Afrikas 4 (7) 1-37

LENZ H 1912 Afrikanische Crustaceen aus schwedischen Sammlungen Ark Zool 7 (29) 1-10MARKERT C L amp I FAULHABER 1965 Lactate dehydrogenase isozyme patterns of sh Journ

exp Zool 159 319-332MAYR E 1963 Animal species and evolution i-xiv 1-797 (Harvard University Press Cambridge

Massachusetts)mdash mdash 1970 Populations species and evolution i-xv 1-453 (Harvard University Press Cambridge

Massachusetts)

POTAMONAUTES LIVIDUS NOV 141

TABLE IEnzymes and buffer systems used to determine biochemical variation in six populations of Potamo-

nautes spp studied

Enzyme Abbreviation EC Number Buffer Tissue Loci

Arginine kinase ARK 2733 A m 1Diaphorase DIA 1622 A h 1Glucose-6-phosphateisomerase GPI 5319 A m 1Hexokinase HEX 2711 B m 1Isocitrate dehydrogenase IDH 11142 C m 2Lactate dehydrogenase LDH 11127 A m 1Malate dehydrogenase MDH 11137 C m 2Malic enzyme ME 11140 B m 1Mannose-phosphate isomerace MPI 5318 B m 1Peptidase (glycyl-leucine as substrate) GL 3411ndash B m 1Peptidase (leucyl-glycyl-glycylas substrate) LGG 3411ndash A h 3Peptidase (leucyl-tyrosineas substrate) LT 3411ndash A B m h 2Peptidase (phenylamine-prolineas substrate) PHP 3411ndash B h 1Phosphoglucomutase PGM 5422 B m 2Phosphoglusonatedehydrogenase PGD 11144 C m 1

Buffer (A) discontinuous Tris-citrate-borate-lithium hydroxide buffer system (Ridgeway et al1970) (B) continuous Tris-borate-EDTA buffer system (Markert amp Faulhaber 1965) and (C) con-tinuous Tris-citrate buffer system (Whitt 1970) Tissue (m) muscle tissue and (h) hepatopancreas (digestive gland)

and all other alleles were scored relative to this value Where more than one locusstained for a particular enzyme the most anodally migrating one was labeled 1and the others labeled sequentially

All numerical analyses were performed using the BIOSYS-1 program (Swof-ford amp Selander 1981) Allele and genotype frequencies were calculated Geno-type frequencies were tested for deviation from frequencies expected under Hardy-Weinberg equilibrium by means of a Acirc2-goodness-of- t test Where more than twoalleles occurred at a locus the genotype frequencies were pooled Percentage poly-morphic loci were calculated for each population using no criterion (loci wereconsidered polymorphic if more than one allele was present at a locus) The meanexpected heterozygosity (H) was also calculated for each locus using unbiasedestimates (Nei 1978) The mean unbiased genetic identity (I ) and distance (D)were calculated for each pairwise comparison (Nei 1978) and a dendrogram con-structed using the measures of genetic identity and the UPGMA clustering algo-rithm (Sneath amp Sokal 1973)

Morphological analyses mdash Prior to dissection crabs were sexed and measuredusing digital Vernier-calipers and a portable computer The populations used forthe genetic analysis were supplemented with morphometric data from specimens

142 G GOUWS B A STEWART amp P E REAVELL

collected earlier at the above localities Seven carapace variables were recorded formorphometric analyses These were carapace length along the medial line (CL)carapace width at the widest part (CWW) posterior carapace width (CWP) thedistance between the postfrontal crest and the anterior carapace margin (PFCD)distance between the medial margins of the orbits (ED) distance between theexorbital teeth (CWA) and the carapace height (CH)

Data were log transformed (common logarithms) prior to analysis All statisticalanalyses were performed using the Statistica Version 51 program (StatSoft Inc1996) Morphological variation between the two forms was determined by meansof a stepwise discriminant function analysis using seven carapace variablesClassi cation functions were calculated using the jackknife procedure ensuringan unbiased classi cation function for determining group assignment Individualswere then reassigned to a group based on the highest a posteriori probability Afrequency histogram of individual canonical variable scores calculated from thediscriminant function analysis was plotted to reveal discrimination between thetwo forms Linear regression analyses were used to test for variation within speci cvariables between the two forms

Gonopods and mouthparts were removed and examined qualitatively using aLeitz stereoscopic dissection microscope and illustrated using a camera lucida orphotographed using a Wild MPS45 camera unit

RESULTS

Biochemical analysis mdash Of the 21 reliably scorable loci nine (ARK LT-1ME LDH MPI PGD DIA LGG-1 and LGG-3) were monomorphic across allpopulations analysed Twelve loci were polymorphic (table II) The LT-2 locus wasthe only locus polymorphic in each population The total number of alleles rangedfrom two in HEX MDH-1 IDH-1 GL PGM-2 PHP-2 and LGG-2 to ve in GPIWithin populations the maximum number of alleles was four found in GPI in theManzibomvu population

Out of thirty cases of polymorphism for all enzyme loci and populations three(10) were shown to deviate from genotype frequencies expected under Hardy-Weinberg equilibrium The LT-2 locus in the University of Zululand A population(Acirc2 D 9468 df D 3 P D 0024) the PHP locus in the Mdibi population(Acirc2 D 7037 df D 1 P D 0008) and the PGM-2 locus in the Dakanenipopulation (Acirc2 D 250 df D 1 P D 0000) were out of equilibrium due toa de cit of heterozygotes carrying the rare allele All other loci conformed toHardy-Weinberg expectations thus supporting a purely genetic interpretation ofthe polymorphisms observed

POTAMONAUTES LIVIDUS NOV 143

TABLE IIDistribution of allele frequencies at nine polymorphic loci in six populations of Potamonautes spp

studied N D sample size refer to table I for enzyme abbreviations

Population

Locus Zululand A Mdibi Mapelane Zululand B Dakaneni Manzibomvu

IDH-2N 41 24 25 13 25 13120 0012 0729 0380 0000 0000 000080 0988 0229 0000 1000 1000 100045 0000 0043 0620 0000 0000 0000

GPIN 56 26 25 13 25 13165 0045 0000 0000 0000 0000 0000150 0000 0000 0000 0000 0000 0038100 0000 0000 0000 0000 0000 003840 0938 1000 1000 0962 0880 0846

iexcl80 0018 0000 0000 0038 0120 0077

HEXN 41 26 25 13 25 13100 1000 1000 1000 0000 0000 000095 0000 0000 0000 1000 1000 1000

MDH-1N 41 26 25 13 25 13100 0988 1000 1000 1000 1000 100090 0012 0000 0000 0000 0000 0000

MDH-2N 41 26 25 13 25 13100 1000 1000 1000 0962 0960 100075 0000 0000 0000 0000 0040 000065 0000 0000 0000 0038 0000 0000

IDH-1N 41 26 25 13 23 7150 0000 0000 0000 1000 0891 0929135 1000 1000 1000 0000 0109 0071

LT-2N 41 26 25 13 25 13250 0049 0019 0020 0000 0000 0000100 0854 0885 0840 0923 0980 0769

0 0098 0096 0140 0077 0020 0231

PGM-1N 52 26 25 13 25 13110 0365 0000 0000 0000 0000 0000100 0212 0000 0000 0038 0140 003890 0423 1000 1000 0923 0800 096275 0000 0000 0000 0038 0060 0000

(continued overleaf)

144 G GOUWS B A STEWART amp P E REAVELL

TABLE II(Continued)

Population

Locus Zululand A Mdibi Mapelane Zululand B Dakaneni Manzibomvu

GLN 41 26 25 13 25 1390 1000 0962 1000 1000 1000 100075 0000 0038 0000 0000 0000 0000

PGM-2N 56 26 25 13 25 13100 1000 1000 1000 0000 0040 000075 0000 0000 0000 1000 0960 1000

PHPN 41 26 25 13 25 13105 1000 0808 1000 1000 1000 100090 0000 0192 0000 0000 0000 0000

LGG-2N 41 26 25 13 24 13100 0854 0942 1000 0846 0979 069290 0146 0058 0000 0154 0021 0308

Genetic variability was low in all populations The percentage polymorphicloci (no criterion) ranged from 95 to 333 in the Mapelane and Dakanenipopulations respectively The mean unbiased expected heterozygosity varied from0034 (in the University of Zululand B population) to 0063 (in the Universityof Zululand A and Manzibomvu populations) The mean number of alleles perlocus ranged from 11 (in the Mapelane population) to 14 (in the Dakaneni andUniversity of Zululand A populations)

The dendrogram constructed based on the genetic identity values obtained bypairwise comparison of populations (table III) clearly distinguished two clusters( g 2) The group representing the form A populations clearly separated from thegroup representing the form B (Potamonautes sidneyi) populations at a geneticidentity value of I D 0829 D D 0187 Three loci contributed signi cantly tothis separation one of them diagnostically The HEX locus showed a xed alleledifference between the individuals of the two forms with the form A individualsbeing xed for the allele HEX100 and the form B (P sidneyi) individuals xed forthe HEX95 allele Strong heterogeneity was observed between the populations ofthe two forms at the IDH-1 and PGM-2 loci With the exception of one individualin the Dakaneni population having a homozygote with the PGM-2100 allele form Aand form B were characterized by the xation of alleles PGM-2100 and PGM-275

POTAMONAUTES LIVIDUS NOV 145

TABLE IIICoef cient matrix of Neirsquos (1978) unbiased genetic identity (above diagonal) and unbiased geneticdistance (below diagonal) for pairwise comparisons of the six populations of Potamonautes studied

Population

Zululand A Mdibi Mapelane Zululand B Dakaneni Manzibomvu

Zululand A currencurrencurrencurrencurren 0958 0949 0840 0855 0842

Mdibi 0043 currencurrencurrencurrencurren 0986 0821 0832 0822

Mapelane 0052 0014 currencurrencurrencurrencurren 0813 0825 0814

Zululand B 0174 0197 0206 currencurrencurrencurrencurren 0998 0999

Dakaneni 0157 0184 0193 0002 currencurrencurrencurrencurren 0994

Manzibomvu 0172 0196 0206 0001 0006 currencurrencurrencurrencurren

Fig 2 UPGMA dendrogram constructed from the matrix of Neirsquos (1978) unbiased genetic identi-ties (I ) using allozyme data from 21 loci

respectively Identity-values for within form comparisons varied from 0949 to0986 (D D 0014 to 0052) and 0994 to 0999 (D D 0001 to 0006) for form Aand form B respectively

Morphometric analysis mdash Individuals from the form A populations couldeasily be distinguished from the form B (P sidneyi) individuals by the possessionof a much more vaulted carapace in ated chelipeds a postfrontal crest whichdiminishes medially and the characteristic silver-blue carapace sheen and brightorange to red chelipeds and pereopods Mature form B (P sidneyi) individualsfrequently attained a larger size class (with CL being representative of size) thandid the mature form A individuals

146 G GOUWS B A STEWART amp P E REAVELL

Three carapace variables (ED CH and CWP) contributed signi cantly to thediscrimination between the two forms in the discriminant function analysis Thehistogram plot of observed canonical variable scores ( g 3) clearly separates thetwo forms with the canonical variable means of the form A and form B individualscalculated at iexcl0996 and 1965 respectively The classi cation function (the linearfunction of variables which best discriminates the individuals of one group fromthe other speci ed groupings) was calculated for individuals of each form Theclassi cation function of the form A group was

Y D 306704 (Log CWP) iexcl 26103 (Log ED) iexcl 228513 (Log CH) iexcl 64156

and of the form B (P sidneyi) group

Y D 35097 (Log ED) iexcl 315543 (Log CH) C 347231 (Log CWP) iexcl 88367

Using the classi cation functions individuals were reassigned to groups basedon highest a posteriori probabilities Of the form A individuals 9437 (134of 142) were correctly classi ed with eight individuals being reassigned to theform B group Of the form B individuals 8889 were correctly reassigned to theP sidneyi group with eight of the 72 individuals being reassigned to the form Agroup

Fig 3 Histogram of scores for specimens of Potamonautes lividus sp nov (form A) and P sidneyiRathbun 1904 (form B) along the canonical variable calculated from a discriminant function

analysis using seven carapace variables

POTAMONAUTES LIVIDUS NOV 147

Comparison of regressions of the most discriminating variables between the twoforms regressed over CL in turn also showed signi cant differences between thetwo forms CH regressed over CL showed highly signi cant differences betweenthe two forms (SS D 0011 df D 1 F D 31266 P lt 0001) as did ED(SS D 0011 df D 1 F D 8333 P lt 0005) and CWP (SS D 0006 df D 1F D 8136 P lt 0005) These represent the most discriminating variables andtheir regressions are represented graphically ( g 4a b c) PFCD (SS D 0199df D 1 F D 52671 P lt 0001) CWW (SS D 0003 df D 1 F D 30963P lt 0001) and CWA (SS D 0001 df D 1 F D 6182 P lt 002) also showedthat there were signi cant differences between the two forms but the discriminantfunction analysis showed them to be redundant in constructing the model

Qualitative analysis mdash Examination of gonopods and mouthparts revealed onlyslight differences in gonopod morphology The terminal segment of gonopod 1of the undescribed form was relatively short and triangular whereas the terminalsegment of gonopod 1 of P sidneyi appears to be substantially longer and moreslender Although the terminal segment is bent away from the medial line in bothforms the terminal segment in P sidneyi possesses a lobe or ange that extendsinwards giving the terminal segment an S-shaped appearance The gonopods andmandibular palps of the two forms are illustrated in g 5

DISCUSSION

The data presented above clearly indicate that the two forms of freshwatercrabs from KwaZulu-Natal are distinct The form A specimens are smaller with amore vaulted carapace that is relatively narrower posteriorly and that possessesa relatively narrower frontal lobe (ED) than that of the Potamonautes sidneyiindividuals

Not only are the two forms clearly distinct both biochemically and morpho-logically but strong evidence suggests that they are reproductively isolated Thepresence of a diagnostic locus HEX xed for alternate alleles in the sympatricpopulation of the two forms indicates that a lack of gene ow and thus repro-ductive isolation exist between the two forms This allows for species recognitionunder the Biological Species Concept (Mayr 1970) under which species are de- ned as ldquogroups of actually or potentially interbreeding populations which arereproductively isolated from other such groupsrdquo (Mayr 1963 19) or ldquogeneticallyisolated (in nature) from other such groupsrdquo (Bock 1986 33) In his model of al-lopatric speciation Bock (1986) suggested that newly evolved species in sympatrywould exert mutually selective demands on each other by means of reproductive

148 G GOUWS B A STEWART amp P E REAVELL

Fig 4 Comparisons of the regressions of (A) Log CH (carapace height) over Log CL (carapacelength) (B) Log ED (eye distance) over Log CL and (C) Log CWP (posterior carapace width) overLog CL between form A (Potamonautes lividus sp nov) and form B (P sidneyi Rathbun 1904) All

differences are signi cant (at the P lt 0005 level)

POTAMONAUTES LIVIDUS NOV 149

Fig 5 A-E form A (Potamonautes lividus sp nov composite of male holotype SAM A43540and unaccessioned material) A carapace outline B left mandibular palp anterior view C leftmandibular palp posterior view D left gonopod 1 anterior view and E left gonopod 1 posteriorview F-J form B (Potamonautes sidneyi Rathbun 1904 unaccessioned specimen) F carapaceoutline G left mandibular palp anterior view H left mandibular palp posterior view I left

gonopod 1 anterior view J left gonopod 1 posterior view

150 G GOUWS B A STEWART amp P E REAVELL

interference and ecological competition This would lead to a divergence of mor-phological and behavioural aspects of feeding reproduction and other ecologicalfeatures The different gonopod morphologies of the two forms may re ect this

The three form A populations clustered separately from the three P sidneyipopulations at a I -value of 0829 Stewart (1997a) calculated the separationI -value between P parvispina Stewart 1997 and P perlatus H Milne Edwards1837 to be 068 An I -value of 066 separated both P perlatus and P brinckiBott 1960 in the Western Cape (Stewart 1997b) and P unispinus Stewart ampCook 1998 and P sidneyi in Mpumalanga (Stewart amp Cook 1998) An I -valueof 0599 was obtained separating P clarus Gouws Stewart amp Coke 2000 andP depressus (Gouws et al 2000) The only species in the genus delineated using ahigher I -value was P granularis Daniels Stewart amp Gibbons 1998 which wasseparated from P perlatus in the Olifants River at a I -value of 088 (Danielset al 1998a 1999) Although slightly higher than most interspeci c values inthe genus the value obtained in this study nevertheless falls within the range (035to 085) speci ed by Thorpe (1982) to indicate congeneric species differencesAllopatric populations showing I -values of less than 085 are unlikely to beconspeci c (Thorpe amp Soleacute-Cava 1994) With the exception of two cases allpairwise comparisons between allopatric populations of the two forms yieldedI -values less than 085

Identity-values were high for comparisons within both the form A (0949 to0986) and P sidneyi (0994 to 0999) groups Intraspeci c I -values are generallyhigh in the genus Potamonautes and disjunct populations within a species tendto be genetically undifferentiated Intraspeci c I -values obtained in six studies(Stewart 1997a b Stewart amp Cook 1998 Daniels et al 1998b 1999) involvingsix Potamonautes species varied from 0902 to 1000 (D D 0000 to 0103)An intraspeci c I -value of 075 was obtained in a comparison of two groups ofP brincki populations across the Cape Peninsula and Cape Flats However thismost probably indicates a species difference and requires further investigation(Stewart 1997b) Given the high intraspeci c I -values characteristic of the genusand those obtained for comparisons within each form the I -value obtainedfor the comparison between the two forms most likely represents a speciesdifference

Bock (1986) also de ned a species as possessing a set of three distinctcharacteristics genetic unity reproductive unity and ecological unity Biochemicaldata provide support for compliance with the rst two criteria for both formsWhile no empirical evidence is as yet available con rming the third factor adegree of macro- and microhabitat segregation and thus ecological segregationis evident between the two forms Potamonautes sidneyi is widespread acrossthe province (Stewart et al 1995) while the other form appears to have a

POTAMONAUTES LIVIDUS NOV 151

more limited distribution in northeastern KwaZulu-Natal restricted to patches ofswamp forest with particular oral assemblages The swamp forests are oftencharacterized by Barringtonia racemosa Syzygium cordatum Ficus trichopodaHibiscus tiliaceus L Rauvola caffra Sond Voacanga thouarsii Roem amp SchultRaphia australis Oberm amp Strey and Podocarpus falcatus (Thunb) R Br exMirb with the fern Stenochlaena tenuifolia (Desv) T Moore often present in theunderstorey (Bruton 1980 Moll 1980) Within the swamp forests the sympatricpopulations appear to show a degree of microhabitat segregation Observationssuggest that P sidneyi has a closer association with water as individuals were nevercollected great distances away from seepage pools and channels owing throughthe forest Conversely individuals of the swamp-forest form were most oftencollected farther from water and their burrows were often among the vegetationObservations suggest that this form is more terrestrial Individuals were noticedto move to higher elevations when the water table rose through the hydromorphicpeat soil ooding their burrows and the surface and they were also more active oncloudy overcast days Evidence of terrestrial adaptation is most likely to be foundin the structure and histology of the organs and tissues involved in respirationfactors such as branchial chamber shape and volume gill structure and formulaand the structure and vascularization of the branchiostegite lining are knownto re ect changes brought upon by the constraints of the terrestrial environment(Greenaway amp Taylor 1976 Diacuteaz amp Rodriacuteguez 1977 Taylor amp Greenaway1979 Cumberlidge 1986 1991 Takeda et al 1996) Although the availabilityof material prohibited the investigation of this aspect future research may prove tobe fruitful and highlight a greater distinction between the two forms

Studies on terrestrial adaptation supplemented by behavioural data that couldillustrate microhabitat and ecological segregation would quantify further thedegree of differentiation between the two forms However two independent datasets biochemical and morphological present strong evidence for the speci c statusof the swamp-forest form

TAXONOMY

Potamonautes lividus sp nov ( gs 6-7)

Material examined mdash Holotype South African Museum (SAM) A43540 one male CL D255 mm Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws andL Hoenson Allotype SAM A43541 one female CL D 245 mm Ficus and Barringtonia swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S 32plusmn2401800E)coll 27 January 1997 by B A Stewart G Gouws and L Hoenson Other material SAM A43542two males Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws

152 G GOUWS B A STEWART amp P E REAVELL

and L Hoenson SAM A43543 one female Lake Nhlabane north of Richards Bay (28plusmn3800500S32plusmn1601700E) coll 27 April 1993 by the University of Zululand Zoology Department SAMA43544 three males one female Mdibi swamp forest along Mdibi stream 8 km north of RichardsBay (28plusmn4202400S 32plusmn0902600E) coll 26 January 1997 by B A Stewart P A Cook M CokeP E Reavell G Gouws and L Hoenson SAM A43545 one male one female Syzygium forestUniversity of Zululand campus (28plusmn5102500S 31plusmn5100200E) coll 24 January 1997 by B A StewartP A Cook P E Reavell G Gouws and L Hoenson SAM A43546 two males two femalesUniversity of Zululand stream owing through campus (28plusmn550S 31plusmn410E) coll 10 September 1995by P E Reavell SAM A41313 one male one female swamp forest Empangeni (28plusmn5102500S31plusmn5100200E) coll 2 August 1994 by M Coke SAM A41155 one male University of ZululandSyzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S 31plusmn450E) coll 10 December1988 by P E Reavell SAM A41153 three males smaller holes in hydromorphic soil Syzygiumcordatum swamp forest University of Zululand (28plusmn450S 31plusmn450E) coll 20 March 1994 byP E Reavell SAM A41156 one female Syzygium cordatum swamp forest University of Zululand(28plusmn450S 31plusmn450E) coll 18 May 1992 by P E Reavell SAM A41154 one male one femaleUniversity of Zululand Syzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S31plusmn450E) coll 10 May 1990 by P E Reavell SAM A43547 two males one female swamp forestUniversity of Zululand (28plusmn450S 31plusmn450E) coll 1 April 1994 by P E Reavell SAM A43548one male one female Syzygium and Bridelia dominated swamp forest University of Zululand(28plusmn5102500S 31plusmn5100200E) coll 7 October 1996 by P E Reavell SAM A43549 one female Mdibiswamp forest Lake Msingazi catchment area north of Richards Bay (28plusmn420S 32plusmn090E) coll5 December 1996 by P E Reavell Albany Museum mdash GEN910 one female Mpolozi swampsMapelane (28plusmn2601300S 32plusmn2402500E) coll 13 February 1991 Albany Museum mdash GEN965 twomales ve females NrsquoKoninga Valley Richards Bay (28plusmn450S 32plusmn030E) coll 7 April 1988

Other material mdash The following specimens included in the collections of the South AfricanMuseum warrant further investigation as although they bear some resemblance to the speciesdescribed below their identi cation is uncertain SAM A41276 one male one female Mbonenidam Mkuze Game Reserve (27plusmn3705700S 32plusmn1504500E) coll 28 October 1994 by M Coke SAMA41299 two males Nxwala stream Mkuze Game Reserve (27plusmn4302300S 32plusmn1601000E) coll 10November 1994 by O Bourquin SAM A41277 one male Rainpool south of entrance False BayPark (28plusmn0000100S 32plusmn2102100E) coll 26 October 1994 by M Coke SAM A41300 two malesKangela rainpoolN2 near Mtubatuba (28plusmn2200000S 32plusmn1103600E) coll 25 October 1994 by M Cokeand SAM A41211 one male Ntambanana (Ntrabanana) Zululand coll by H H Curson

Type locality mdash South Africa KwaZulu-Natal Barringtonia and Ficus swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S32plusmn2401800E)

Distribution mdash At present known only from the swamp forests (characterizedby Barringtonia racemosa Syzygium cordatum and Ficus trichopoda vegetationand spongy hydromorphic peat-soil) in the vicinity of Richards Bay Empangeniand the Mapelane Nature Reserve It is probable that the distribution of the speciesmay extend into low-lying areas to the east of the Drakensberg escarpment in theprovince of Mpumalanga and into Mozambique

Etymology mdash From the Latin ldquolividusrdquo meaning ldquobluerdquo or ldquolight bluerdquoreferring to the characteristic silver-blue sheen of the carapace The epitheton isan adjective agreeing in gender with the (masculine) generic name

POTAMONAUTES LIVIDUS NOV 153

Fig 6 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A wholeanimal dorsal aspect B whole animal ventral aspect C cephalothorax frontal aspect

Diagnosis mdash Carapace distinctly vaulted and relatively narrow posteriorlyEpibranchial teeth absent and anterolateral margin of the carapace smooth Post-frontal crest indistinct medially with frontal lobe projecting downwards Cara-pace characteristically orange to red with silver-blue sheen Chelipeds and limbs

154 G GOUWS B A STEWART amp P E REAVELL

bright orange to red with lighter cheliped and dactyl tips Chela in ated and highlyarched

Description of male holotype mdash Size Measurements of the holotype and theranges of other specimens are given in table IV

Carapace ( gs 6A C 7A) Carapace and limbs characteristically orange tored with the carapace possessing a silver-blue sheen when alive Preserved spec-imens (70 ethanol) appear less orange and the carapace retains a blue-greycolour Cephalothorax ovoid distinctly vaulted branchial region highly convex( g 6A C) maximum height and width at anterior third (ratio CHCL D 065CWWCL D 145) Anterior margin straight Urogastric grooves moderately wellde ned Cardiac grooves shallow and poorly de ned Carapace otherwise smoothPostfrontal crest smooth curves forward medially Postfrontal crest diminishesabove inner orbit margins though well de ned immediately lateral to forked mid-point groove by means of two indentations anterior to crest indicating epigas-tric lobes Exorbital teeth moderately sharp but small Epibranchial teeth ab-sent Anterolateral margin posterior to postfrontal crest smooth margin curvingin over carapace in branchial region though indistinctly Each ank has a longitu-dinal groove dividing the subhepatic from the pterygostomial region with verticalgroove running from longitudinal groove joining anterolateral margin between ex-orbital tooth and postfrontal crest

Sternites ( gs 6B 7B) Sternites 1 and 2 fused no suture visible First suture(sternal groove) between sternites 2 and 3 complete Second sternal groove

TABLE IVPotamonautes lividus sp nov wet weight (in g) and measurements (in mm) for the male holotype

and ranges for other individuals examined (maximum of 77 males and 70 females)

Variable Abbreviation Holotype Males Females

Wet weight WW 242 05-214 07-183Carapace length CL 255 84-247 89-276Carapace widest width CWW 370 114-360 118-373Carapace posterior width CWP 281 90-269 86-306Distance between postfrontal crest

and anterior margin PFCD 43 12-222 15-46Distance between orbits ED 114 42-119 43-123Distance between exorbital teeth CWA 259 96-254 96-262Carapace height CH 165 48-171 50-162Width of sixth abdominal segment AW6 75 28-74 31-240Major cheliped propodus length MCPL 427 71-402 76-291Major cheliped propodus height MCPH 198 28-189 28-142Pereopod 2 merus length P2ML 189 50-181 51-171Pereopod 2 merus width P2MW 58 19-56 18-59

POTAMONAUTES LIVIDUS NOV 155

Fig 7 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A carapaceoutline B thoracic sternum C right cheliped dactylus and propodus D left cheliped dactylusand propodus E left third maxilliped F left mandible and mandibular palp posterior view G leftmandibular palp posterior view H left mandibular palp anterior view I left gonopod 1 anteriorview J terminal segment left gonopod 1 anterior view K left gonopod 1 posterior view L leftgonopod 2 anterior view Scale lines represent 1 mm except for A-D where they represent 10 mm

156 G GOUWS B A STEWART amp P E REAVELL

between sternites 3 and 4 complete laterally becoming shallower mediallysloping sharply towards abdominopelvic region

Third maxillipeds ( gs 6C 7E) Filling entire buccal frame except for ovalefferent respiratory openings short agellum present on exopods ischium smoothwith moderately deep vertical groove

Mandibular palp ( g 7F G H) Mandibular palp with two segments terminalsegment undivided with a dense tuft of setae on posterior surface of angeof terminal segment Margins generally hirsute Subterminal segment slightlyenlarged distally

Chelipeds and walking legs ( gs 6A 7C D) Chelipeds markedly unequaldactylus of right cheliped strongly arched 163 times length of dactylus of leftcheliped Both dactyli armed with up to 20 cutting teeth three to four of whichare slightly larger and more prominent Propodus of right cheliped markedlyin ated 168 times longer and 20 times wider than that of left cheliped Pollexpossesses 20 cutting teeth four to ve of which are more prominent Carpi ofboth chelipeds possess one prominent and three rudimentary teeth Margins ofmeri granulose small blunt spine on anterior surface no spine on anterior-inferiormargin Pereopods generally slender (pereopod 2 merus length width D 328 andpereopod 5 merus lengthwidth D 271) P3 longest P5 shortest ventral marginsof propodi and meri smooth dorsal margin with ne sharp bristles dactyli endingin sharp points with margins bearing a series of sharp spinelike bristles

Pleon ( gs 6B 7B) First ve segments broad and short last two segmentslonger terminal segment rounded at distal end

Pleopods ( g 7I J K) Pleopod 1 (gonopod 1) terminal segment short 025times length of subterminal segment terminal segment curves away from mid-line when viewed posteriorly widest at base ending in pointed tip Subterminalsegment of pleopod 1 tapers distally inner lateral margin slightly irregular outerlateral margin straighter both margins hirsute Posterior surface with twisting lon-gitudinal groove extending length of subterminal and terminal segment Groovenot visible on anterior surface Posterior surface and margins of groove hirsutePleopod 2 (gonopod 2) terminal segment lament-like 05 the length of subter-minal segment curving slightly towards medial line proximally curves away frommedial line distally ( g 7L) Subterminal segment widest at base tapering sharplyinwards at 04 of length forms narrow process supporting terminal segment

Variation mdash All individuals are characteristically dark orange to red witha silver-blue sheen to the carapace while the chelipeds vary in colour frombright orange-red to a lighter yellow-orange All individuals are characterized byhighly vaulted carapaces and downwardly projecting frontal lobes The postfrontalcrest which is most pronounced laterally (from directly above the orbits to theanterolateral margin) and incomplete medially is often more distinct in the smaller

POTAMONAUTES LIVIDUS NOV 157

individuals Chelipeds are not always typically arched enclosing a large ovoidspace as in the holotype Chelipeds of smaller individuals although in ated areless arched and often tight closing with the small cutting teeth more obviousChelipeds of females and small males in particular from the Mdibi and Universityof Zululand localities have propodi that are relatively high with in ated palmsand relatively short tightly closing chelae which project slightly downwardsHeterochely has been demonstrated in most Potamonautes-species occurring inSouth Africa (Siegfried 1972 Raubenheimer 1986 Stewart et al 1995 Stewart1997a b Stewart amp Cook 1998 Daniels et al 1998a Gouws et al 2000) Withinthe species 76 of the specimens were right-handed with 11 being left-handedand 13 being of equal or subequal (differing by less than one millimeter) sizeOf the males 79 were right-handed 8 left-handed and 13 equal or subequalFemales had 74 right-handedness 13 left-handedness and in 13 of caseschelipeds were equal or subequal The abdomen of mature females completelyoverlaps the coxae of the pereopods The smallest mature female had a CL of167 mm with the largest immature female having a CL of 159 indicating that thepubertal moult occurs approximately between the 14 mm and 18 mm size classes

Remarks mdash Potamonautes lividus sp nov can readily be distinguished from theten other species in the genus Potamonautes known to occur within South AfricaPotamonautes warreni Calman 1918 P dentatus P parvispina and P unispinusall bear a singular spine or a series of teeth on the anterolateral margins whereasP lividus sp nov is smooth Potamonautes perlatus P sidneyi and P granularisare all larger crabs with in ated arched carapaces with complete distinct post-frontal crests and scabrosity or granulation of the anterior margins orbits epi-branchial corners or postfrontal crests Potamonautes lividus sp nov has smoothcarapace margins and a incomplete postfrontal crest The terminal segment ofgonopod 1 in P lividus sp nov is relatively short and triangular and curves awayfrom the medial line when viewed posteriorly while that of P sidneyi is relativelylonger more slender and more S-shaped The postfrontal crest of P sidneyi mayjoin the anterolateral margin at a relatively sharp angle and form a pronouncedepibranchial corner along the anterolateral margin The anterolateral margin inP lividus sp nov is more rounded and the epibranchial corners slope down to-wards the anks Potamonautes granularis is chocolate brown with orange tips tothe chelipeds Potamonautes brincki is a smaller crab with a smoother carapacethough also chocolate to reddish-brown in colour with a nely granulated antero-lateral margin which does not curve in over the carapace in the branchial region(Stewart 1997b) Potamonautes depressus and P clarus both have rounded epi-branchial corners and smooth carapaces though these are relatively shallow andhave attened dorsal surfaces Both are characterized by long slender limbs Pota-monautes depressus is brown to green-brown in colour while P clarus is brightorange in colour

158 G GOUWS B A STEWART amp P E REAVELL

A number of species from further a eld bear a super cial resemblance toP lividus sp nov particularly with regard to carapace morphology though in mostcases they can be readily distinguished Potamonautes pilosus Hilgendorf 1898 isknown from East Africa and is a small crab with a CWW of less than 25 mmSpecimens possess a weak postfrontal crest which along with the anterolateralmargin can be granulated (Hilgendorf 1898 Bott 1955) Potamonautes neumanniHilgendorf 1898 is known from East Africa and has a characteristically vaultedcarapace without a complete distinct postfrontal crest (Hilgendorf 1898 Bott1955) The postfrontal crest is more distinct in P lividus particularly laterally andthe exorbital teeth are sharper and more de ned in P lividus than in P neumanniThe terminal segment of gonopod 1 is longer and more slender in P neumannithan in P lividus and curves distinctly outwards The subterminal segment ofgonopod 1 is wider at its apex in P neumanni than in P lividus Additionally thecarapace of preserved specimens of P neumanni is typically grey in colour whileliving specimens are violet in colour with bright olive-green limbs and chelipeds(Hilgendorf 1898) Potamonautes ballayi acristatus Bott 1955 has an incompletepostfrontal crest only present above the orbits and small and blunt exorbital teethThe major chela although highly arched and the minor chela are long and moreslender than those of P lividus sp nov The terminal segment of gonopod 1 ofP granviki Colosi 1924 is curved towards the medial line when viewed posteriorly(Bott 1955) The chelae of both P berardi berardi Audouin 1826 and P b ignestiiParisi 1923 are relatively short and high with stout downward-projecting ngersThe anterior margin of the frontal lobe of P b berardi shows a distinct invaginationand the anterolateral margin appears sharp and less rounded than in P lividus spnov while the postfrontal crest of P b ignestii is complete and has a fairly longmedial groove Potamonautes emini emini Hilgendorf 1892 are generally smallcrabs with a less in ated carapace and short stout chelipeds The subterminaland terminal segments of gonopod 1 are of more or less equal size (Bott 1955)Potamonautes e semilunaris Bott 1955 and P luashiensis Bott 1955 are alsosmall crabs (CWW lt 20 mm) with the postfrontal crest only visible laterally andin the case of P luashiensis the anterolateral margin and postfrontal crest mayshow granulation Potamonautes didieri Rathbun 1904 possesses a more completerounded postfrontal crest and shorter more stout chelipeds (Bott 1955)

ACKNOWLEDGEMENTS

Financial assistance was kindly provided by the World Wildlife Fund - SouthAfrica the Foundation for Research Development and the University of ZululandThe KwaZulu-Natal Nature Conservation Services provided accommodation and

POTAMONAUTES LIVIDUS NOV 159

logistic support Liz Hoenson Peter Cook Mike Coke and Tyrone Ridgway arethanked for assistance in the eld and Michelle van der Merwe is thanked foraiding in the photography and drafting of gures The authors wish to thank ananonymous reviewer for comments on the manuscript

REFERENCES

BARNARD K H 1935 Scienti c results of the Vernay-Lang Kalahari expedition March toSeptember 1930 Crustacea Ann Transvaal Mus 16 481-492

mdash mdash 1950 Descriptive catalogue of South African decapod Crustacea (crabs and shrimps) AnnSouth African Mus 38 1-837

BOCK W J 1986 Species concepts speciation and macroevolution In K IWATSUKIP H RAVEN amp W J BOCK (eds) Modern aspects of species 31-57 (University of TokyoPress Tokyo)

BOTT R 1955 Die Suumlsswasserkrabben von Afrika (Crust Decap) und ihre StammesgeschichteAnn Mus R Congo Belge (C Zool) 1 (33) 209-352 pls 1-30

BRUTON M N 1980 An outline of the ecology of the Mgobezeleni lake system at Sodwana withemphasis on the mangrove community In M N BRUTON amp K H COOPER (eds) Studieson the ecology of Maputaland 408-426 (Rhodes University Grahamstown)

CUMBERLIDGE N 1986 Ventilation of the branchial chambers in the amphibious West Africanfreshwater crab Sudanonautes (Convexonautes) aubryi monodi (Balss 1929) (BrachyuraPotamonautidae)Hydrobiol 134 53-65

mdash mdash 1991 The respiratory system of Globonautes macropus (Rathbun 1898) a terrestrialfreshwater crab from Liberia (GecarcinucoideaGecarcinucidae)Crustaceana 61 (1) 69-80

DANIELS S R B A STEWART amp M J GIBBONS 1998a Potamonautes granularis sp nov(Brachyura Potamonautidae) a new cryptic species of river crab from the Olifants Riversystem South Africa Crustaceana 71 (8) 885-903

mdash mdash mdash mdash amp mdash mdash 1998b Genetic and morphometric variation in the potamonautid river crabPotamonautes parvispina (Decapoda Potamonautidae) from two Western Cape rivers SouthAfrica Journ nat Hist London 32 1245-1258

mdash mdash mdash mdash amp mdash mdash 1999 Genetic structure among populations of Potamonautes perlatus(Decapoda Potamonautidae) from the Olifants River system in the Western Cape SouthAfrica Journ Zool London 249 (2) 137-142

DIacuteAZ H amp G RODRIacuteGUEZ 1977 The branchial chamber in terrestrial crabs a comparative studyBiol Bull Woods Hole 153 485-504

GOUWS G B A STEWART amp M COKE 2000 Evidence for a new species of river crab(Decapoda Brachyura Potamonautidae) from the Drakensberg South Africa Journ CrustBiol 20 (4) 743-758

GREENAWAY P amp H H TAYLOR 1976 Aerial gas exchange in Australian arid-zone crabParathelphusa transversa Von Martens Nature London 262 711-713

HILGENDORF F 1898 Die Land- und Suumlsswasser-Dekapoden Ostafrikas Die Thierwelt DeutschOst-Afrikas 4 (7) 1-37

LENZ H 1912 Afrikanische Crustaceen aus schwedischen Sammlungen Ark Zool 7 (29) 1-10MARKERT C L amp I FAULHABER 1965 Lactate dehydrogenase isozyme patterns of sh Journ

exp Zool 159 319-332MAYR E 1963 Animal species and evolution i-xiv 1-797 (Harvard University Press Cambridge

Massachusetts)mdash mdash 1970 Populations species and evolution i-xv 1-453 (Harvard University Press Cambridge

Massachusetts)

142 G GOUWS B A STEWART amp P E REAVELL

collected earlier at the above localities Seven carapace variables were recorded formorphometric analyses These were carapace length along the medial line (CL)carapace width at the widest part (CWW) posterior carapace width (CWP) thedistance between the postfrontal crest and the anterior carapace margin (PFCD)distance between the medial margins of the orbits (ED) distance between theexorbital teeth (CWA) and the carapace height (CH)

Data were log transformed (common logarithms) prior to analysis All statisticalanalyses were performed using the Statistica Version 51 program (StatSoft Inc1996) Morphological variation between the two forms was determined by meansof a stepwise discriminant function analysis using seven carapace variablesClassi cation functions were calculated using the jackknife procedure ensuringan unbiased classi cation function for determining group assignment Individualswere then reassigned to a group based on the highest a posteriori probability Afrequency histogram of individual canonical variable scores calculated from thediscriminant function analysis was plotted to reveal discrimination between thetwo forms Linear regression analyses were used to test for variation within speci cvariables between the two forms

Gonopods and mouthparts were removed and examined qualitatively using aLeitz stereoscopic dissection microscope and illustrated using a camera lucida orphotographed using a Wild MPS45 camera unit

RESULTS

Biochemical analysis mdash Of the 21 reliably scorable loci nine (ARK LT-1ME LDH MPI PGD DIA LGG-1 and LGG-3) were monomorphic across allpopulations analysed Twelve loci were polymorphic (table II) The LT-2 locus wasthe only locus polymorphic in each population The total number of alleles rangedfrom two in HEX MDH-1 IDH-1 GL PGM-2 PHP-2 and LGG-2 to ve in GPIWithin populations the maximum number of alleles was four found in GPI in theManzibomvu population

Out of thirty cases of polymorphism for all enzyme loci and populations three(10) were shown to deviate from genotype frequencies expected under Hardy-Weinberg equilibrium The LT-2 locus in the University of Zululand A population(Acirc2 D 9468 df D 3 P D 0024) the PHP locus in the Mdibi population(Acirc2 D 7037 df D 1 P D 0008) and the PGM-2 locus in the Dakanenipopulation (Acirc2 D 250 df D 1 P D 0000) were out of equilibrium due toa de cit of heterozygotes carrying the rare allele All other loci conformed toHardy-Weinberg expectations thus supporting a purely genetic interpretation ofthe polymorphisms observed

POTAMONAUTES LIVIDUS NOV 143

TABLE IIDistribution of allele frequencies at nine polymorphic loci in six populations of Potamonautes spp

studied N D sample size refer to table I for enzyme abbreviations

Population

Locus Zululand A Mdibi Mapelane Zululand B Dakaneni Manzibomvu

IDH-2N 41 24 25 13 25 13120 0012 0729 0380 0000 0000 000080 0988 0229 0000 1000 1000 100045 0000 0043 0620 0000 0000 0000

GPIN 56 26 25 13 25 13165 0045 0000 0000 0000 0000 0000150 0000 0000 0000 0000 0000 0038100 0000 0000 0000 0000 0000 003840 0938 1000 1000 0962 0880 0846

iexcl80 0018 0000 0000 0038 0120 0077

HEXN 41 26 25 13 25 13100 1000 1000 1000 0000 0000 000095 0000 0000 0000 1000 1000 1000

MDH-1N 41 26 25 13 25 13100 0988 1000 1000 1000 1000 100090 0012 0000 0000 0000 0000 0000

MDH-2N 41 26 25 13 25 13100 1000 1000 1000 0962 0960 100075 0000 0000 0000 0000 0040 000065 0000 0000 0000 0038 0000 0000

IDH-1N 41 26 25 13 23 7150 0000 0000 0000 1000 0891 0929135 1000 1000 1000 0000 0109 0071

LT-2N 41 26 25 13 25 13250 0049 0019 0020 0000 0000 0000100 0854 0885 0840 0923 0980 0769

0 0098 0096 0140 0077 0020 0231

PGM-1N 52 26 25 13 25 13110 0365 0000 0000 0000 0000 0000100 0212 0000 0000 0038 0140 003890 0423 1000 1000 0923 0800 096275 0000 0000 0000 0038 0060 0000

(continued overleaf)

144 G GOUWS B A STEWART amp P E REAVELL

TABLE II(Continued)

Population

Locus Zululand A Mdibi Mapelane Zululand B Dakaneni Manzibomvu

GLN 41 26 25 13 25 1390 1000 0962 1000 1000 1000 100075 0000 0038 0000 0000 0000 0000

PGM-2N 56 26 25 13 25 13100 1000 1000 1000 0000 0040 000075 0000 0000 0000 1000 0960 1000

PHPN 41 26 25 13 25 13105 1000 0808 1000 1000 1000 100090 0000 0192 0000 0000 0000 0000

LGG-2N 41 26 25 13 24 13100 0854 0942 1000 0846 0979 069290 0146 0058 0000 0154 0021 0308

Genetic variability was low in all populations The percentage polymorphicloci (no criterion) ranged from 95 to 333 in the Mapelane and Dakanenipopulations respectively The mean unbiased expected heterozygosity varied from0034 (in the University of Zululand B population) to 0063 (in the Universityof Zululand A and Manzibomvu populations) The mean number of alleles perlocus ranged from 11 (in the Mapelane population) to 14 (in the Dakaneni andUniversity of Zululand A populations)

The dendrogram constructed based on the genetic identity values obtained bypairwise comparison of populations (table III) clearly distinguished two clusters( g 2) The group representing the form A populations clearly separated from thegroup representing the form B (Potamonautes sidneyi) populations at a geneticidentity value of I D 0829 D D 0187 Three loci contributed signi cantly tothis separation one of them diagnostically The HEX locus showed a xed alleledifference between the individuals of the two forms with the form A individualsbeing xed for the allele HEX100 and the form B (P sidneyi) individuals xed forthe HEX95 allele Strong heterogeneity was observed between the populations ofthe two forms at the IDH-1 and PGM-2 loci With the exception of one individualin the Dakaneni population having a homozygote with the PGM-2100 allele form Aand form B were characterized by the xation of alleles PGM-2100 and PGM-275

POTAMONAUTES LIVIDUS NOV 145

TABLE IIICoef cient matrix of Neirsquos (1978) unbiased genetic identity (above diagonal) and unbiased geneticdistance (below diagonal) for pairwise comparisons of the six populations of Potamonautes studied

Population

Zululand A Mdibi Mapelane Zululand B Dakaneni Manzibomvu

Zululand A currencurrencurrencurrencurren 0958 0949 0840 0855 0842

Mdibi 0043 currencurrencurrencurrencurren 0986 0821 0832 0822

Mapelane 0052 0014 currencurrencurrencurrencurren 0813 0825 0814

Zululand B 0174 0197 0206 currencurrencurrencurrencurren 0998 0999

Dakaneni 0157 0184 0193 0002 currencurrencurrencurrencurren 0994

Manzibomvu 0172 0196 0206 0001 0006 currencurrencurrencurrencurren

Fig 2 UPGMA dendrogram constructed from the matrix of Neirsquos (1978) unbiased genetic identi-ties (I ) using allozyme data from 21 loci

respectively Identity-values for within form comparisons varied from 0949 to0986 (D D 0014 to 0052) and 0994 to 0999 (D D 0001 to 0006) for form Aand form B respectively

Morphometric analysis mdash Individuals from the form A populations couldeasily be distinguished from the form B (P sidneyi) individuals by the possessionof a much more vaulted carapace in ated chelipeds a postfrontal crest whichdiminishes medially and the characteristic silver-blue carapace sheen and brightorange to red chelipeds and pereopods Mature form B (P sidneyi) individualsfrequently attained a larger size class (with CL being representative of size) thandid the mature form A individuals

146 G GOUWS B A STEWART amp P E REAVELL

Three carapace variables (ED CH and CWP) contributed signi cantly to thediscrimination between the two forms in the discriminant function analysis Thehistogram plot of observed canonical variable scores ( g 3) clearly separates thetwo forms with the canonical variable means of the form A and form B individualscalculated at iexcl0996 and 1965 respectively The classi cation function (the linearfunction of variables which best discriminates the individuals of one group fromthe other speci ed groupings) was calculated for individuals of each form Theclassi cation function of the form A group was

Y D 306704 (Log CWP) iexcl 26103 (Log ED) iexcl 228513 (Log CH) iexcl 64156

and of the form B (P sidneyi) group

Y D 35097 (Log ED) iexcl 315543 (Log CH) C 347231 (Log CWP) iexcl 88367

Using the classi cation functions individuals were reassigned to groups basedon highest a posteriori probabilities Of the form A individuals 9437 (134of 142) were correctly classi ed with eight individuals being reassigned to theform B group Of the form B individuals 8889 were correctly reassigned to theP sidneyi group with eight of the 72 individuals being reassigned to the form Agroup

Fig 3 Histogram of scores for specimens of Potamonautes lividus sp nov (form A) and P sidneyiRathbun 1904 (form B) along the canonical variable calculated from a discriminant function

analysis using seven carapace variables

POTAMONAUTES LIVIDUS NOV 147

Comparison of regressions of the most discriminating variables between the twoforms regressed over CL in turn also showed signi cant differences between thetwo forms CH regressed over CL showed highly signi cant differences betweenthe two forms (SS D 0011 df D 1 F D 31266 P lt 0001) as did ED(SS D 0011 df D 1 F D 8333 P lt 0005) and CWP (SS D 0006 df D 1F D 8136 P lt 0005) These represent the most discriminating variables andtheir regressions are represented graphically ( g 4a b c) PFCD (SS D 0199df D 1 F D 52671 P lt 0001) CWW (SS D 0003 df D 1 F D 30963P lt 0001) and CWA (SS D 0001 df D 1 F D 6182 P lt 002) also showedthat there were signi cant differences between the two forms but the discriminantfunction analysis showed them to be redundant in constructing the model

Qualitative analysis mdash Examination of gonopods and mouthparts revealed onlyslight differences in gonopod morphology The terminal segment of gonopod 1of the undescribed form was relatively short and triangular whereas the terminalsegment of gonopod 1 of P sidneyi appears to be substantially longer and moreslender Although the terminal segment is bent away from the medial line in bothforms the terminal segment in P sidneyi possesses a lobe or ange that extendsinwards giving the terminal segment an S-shaped appearance The gonopods andmandibular palps of the two forms are illustrated in g 5

DISCUSSION

The data presented above clearly indicate that the two forms of freshwatercrabs from KwaZulu-Natal are distinct The form A specimens are smaller with amore vaulted carapace that is relatively narrower posteriorly and that possessesa relatively narrower frontal lobe (ED) than that of the Potamonautes sidneyiindividuals

Not only are the two forms clearly distinct both biochemically and morpho-logically but strong evidence suggests that they are reproductively isolated Thepresence of a diagnostic locus HEX xed for alternate alleles in the sympatricpopulation of the two forms indicates that a lack of gene ow and thus repro-ductive isolation exist between the two forms This allows for species recognitionunder the Biological Species Concept (Mayr 1970) under which species are de- ned as ldquogroups of actually or potentially interbreeding populations which arereproductively isolated from other such groupsrdquo (Mayr 1963 19) or ldquogeneticallyisolated (in nature) from other such groupsrdquo (Bock 1986 33) In his model of al-lopatric speciation Bock (1986) suggested that newly evolved species in sympatrywould exert mutually selective demands on each other by means of reproductive

148 G GOUWS B A STEWART amp P E REAVELL

Fig 4 Comparisons of the regressions of (A) Log CH (carapace height) over Log CL (carapacelength) (B) Log ED (eye distance) over Log CL and (C) Log CWP (posterior carapace width) overLog CL between form A (Potamonautes lividus sp nov) and form B (P sidneyi Rathbun 1904) All

differences are signi cant (at the P lt 0005 level)

POTAMONAUTES LIVIDUS NOV 149

Fig 5 A-E form A (Potamonautes lividus sp nov composite of male holotype SAM A43540and unaccessioned material) A carapace outline B left mandibular palp anterior view C leftmandibular palp posterior view D left gonopod 1 anterior view and E left gonopod 1 posteriorview F-J form B (Potamonautes sidneyi Rathbun 1904 unaccessioned specimen) F carapaceoutline G left mandibular palp anterior view H left mandibular palp posterior view I left

gonopod 1 anterior view J left gonopod 1 posterior view

150 G GOUWS B A STEWART amp P E REAVELL

interference and ecological competition This would lead to a divergence of mor-phological and behavioural aspects of feeding reproduction and other ecologicalfeatures The different gonopod morphologies of the two forms may re ect this

The three form A populations clustered separately from the three P sidneyipopulations at a I -value of 0829 Stewart (1997a) calculated the separationI -value between P parvispina Stewart 1997 and P perlatus H Milne Edwards1837 to be 068 An I -value of 066 separated both P perlatus and P brinckiBott 1960 in the Western Cape (Stewart 1997b) and P unispinus Stewart ampCook 1998 and P sidneyi in Mpumalanga (Stewart amp Cook 1998) An I -valueof 0599 was obtained separating P clarus Gouws Stewart amp Coke 2000 andP depressus (Gouws et al 2000) The only species in the genus delineated using ahigher I -value was P granularis Daniels Stewart amp Gibbons 1998 which wasseparated from P perlatus in the Olifants River at a I -value of 088 (Danielset al 1998a 1999) Although slightly higher than most interspeci c values inthe genus the value obtained in this study nevertheless falls within the range (035to 085) speci ed by Thorpe (1982) to indicate congeneric species differencesAllopatric populations showing I -values of less than 085 are unlikely to beconspeci c (Thorpe amp Soleacute-Cava 1994) With the exception of two cases allpairwise comparisons between allopatric populations of the two forms yieldedI -values less than 085

Identity-values were high for comparisons within both the form A (0949 to0986) and P sidneyi (0994 to 0999) groups Intraspeci c I -values are generallyhigh in the genus Potamonautes and disjunct populations within a species tendto be genetically undifferentiated Intraspeci c I -values obtained in six studies(Stewart 1997a b Stewart amp Cook 1998 Daniels et al 1998b 1999) involvingsix Potamonautes species varied from 0902 to 1000 (D D 0000 to 0103)An intraspeci c I -value of 075 was obtained in a comparison of two groups ofP brincki populations across the Cape Peninsula and Cape Flats However thismost probably indicates a species difference and requires further investigation(Stewart 1997b) Given the high intraspeci c I -values characteristic of the genusand those obtained for comparisons within each form the I -value obtainedfor the comparison between the two forms most likely represents a speciesdifference

Bock (1986) also de ned a species as possessing a set of three distinctcharacteristics genetic unity reproductive unity and ecological unity Biochemicaldata provide support for compliance with the rst two criteria for both formsWhile no empirical evidence is as yet available con rming the third factor adegree of macro- and microhabitat segregation and thus ecological segregationis evident between the two forms Potamonautes sidneyi is widespread acrossthe province (Stewart et al 1995) while the other form appears to have a

POTAMONAUTES LIVIDUS NOV 151

more limited distribution in northeastern KwaZulu-Natal restricted to patches ofswamp forest with particular oral assemblages The swamp forests are oftencharacterized by Barringtonia racemosa Syzygium cordatum Ficus trichopodaHibiscus tiliaceus L Rauvola caffra Sond Voacanga thouarsii Roem amp SchultRaphia australis Oberm amp Strey and Podocarpus falcatus (Thunb) R Br exMirb with the fern Stenochlaena tenuifolia (Desv) T Moore often present in theunderstorey (Bruton 1980 Moll 1980) Within the swamp forests the sympatricpopulations appear to show a degree of microhabitat segregation Observationssuggest that P sidneyi has a closer association with water as individuals were nevercollected great distances away from seepage pools and channels owing throughthe forest Conversely individuals of the swamp-forest form were most oftencollected farther from water and their burrows were often among the vegetationObservations suggest that this form is more terrestrial Individuals were noticedto move to higher elevations when the water table rose through the hydromorphicpeat soil ooding their burrows and the surface and they were also more active oncloudy overcast days Evidence of terrestrial adaptation is most likely to be foundin the structure and histology of the organs and tissues involved in respirationfactors such as branchial chamber shape and volume gill structure and formulaand the structure and vascularization of the branchiostegite lining are knownto re ect changes brought upon by the constraints of the terrestrial environment(Greenaway amp Taylor 1976 Diacuteaz amp Rodriacuteguez 1977 Taylor amp Greenaway1979 Cumberlidge 1986 1991 Takeda et al 1996) Although the availabilityof material prohibited the investigation of this aspect future research may prove tobe fruitful and highlight a greater distinction between the two forms

Studies on terrestrial adaptation supplemented by behavioural data that couldillustrate microhabitat and ecological segregation would quantify further thedegree of differentiation between the two forms However two independent datasets biochemical and morphological present strong evidence for the speci c statusof the swamp-forest form

TAXONOMY

Potamonautes lividus sp nov ( gs 6-7)

Material examined mdash Holotype South African Museum (SAM) A43540 one male CL D255 mm Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws andL Hoenson Allotype SAM A43541 one female CL D 245 mm Ficus and Barringtonia swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S 32plusmn2401800E)coll 27 January 1997 by B A Stewart G Gouws and L Hoenson Other material SAM A43542two males Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws

152 G GOUWS B A STEWART amp P E REAVELL

and L Hoenson SAM A43543 one female Lake Nhlabane north of Richards Bay (28plusmn3800500S32plusmn1601700E) coll 27 April 1993 by the University of Zululand Zoology Department SAMA43544 three males one female Mdibi swamp forest along Mdibi stream 8 km north of RichardsBay (28plusmn4202400S 32plusmn0902600E) coll 26 January 1997 by B A Stewart P A Cook M CokeP E Reavell G Gouws and L Hoenson SAM A43545 one male one female Syzygium forestUniversity of Zululand campus (28plusmn5102500S 31plusmn5100200E) coll 24 January 1997 by B A StewartP A Cook P E Reavell G Gouws and L Hoenson SAM A43546 two males two femalesUniversity of Zululand stream owing through campus (28plusmn550S 31plusmn410E) coll 10 September 1995by P E Reavell SAM A41313 one male one female swamp forest Empangeni (28plusmn5102500S31plusmn5100200E) coll 2 August 1994 by M Coke SAM A41155 one male University of ZululandSyzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S 31plusmn450E) coll 10 December1988 by P E Reavell SAM A41153 three males smaller holes in hydromorphic soil Syzygiumcordatum swamp forest University of Zululand (28plusmn450S 31plusmn450E) coll 20 March 1994 byP E Reavell SAM A41156 one female Syzygium cordatum swamp forest University of Zululand(28plusmn450S 31plusmn450E) coll 18 May 1992 by P E Reavell SAM A41154 one male one femaleUniversity of Zululand Syzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S31plusmn450E) coll 10 May 1990 by P E Reavell SAM A43547 two males one female swamp forestUniversity of Zululand (28plusmn450S 31plusmn450E) coll 1 April 1994 by P E Reavell SAM A43548one male one female Syzygium and Bridelia dominated swamp forest University of Zululand(28plusmn5102500S 31plusmn5100200E) coll 7 October 1996 by P E Reavell SAM A43549 one female Mdibiswamp forest Lake Msingazi catchment area north of Richards Bay (28plusmn420S 32plusmn090E) coll5 December 1996 by P E Reavell Albany Museum mdash GEN910 one female Mpolozi swampsMapelane (28plusmn2601300S 32plusmn2402500E) coll 13 February 1991 Albany Museum mdash GEN965 twomales ve females NrsquoKoninga Valley Richards Bay (28plusmn450S 32plusmn030E) coll 7 April 1988

Other material mdash The following specimens included in the collections of the South AfricanMuseum warrant further investigation as although they bear some resemblance to the speciesdescribed below their identi cation is uncertain SAM A41276 one male one female Mbonenidam Mkuze Game Reserve (27plusmn3705700S 32plusmn1504500E) coll 28 October 1994 by M Coke SAMA41299 two males Nxwala stream Mkuze Game Reserve (27plusmn4302300S 32plusmn1601000E) coll 10November 1994 by O Bourquin SAM A41277 one male Rainpool south of entrance False BayPark (28plusmn0000100S 32plusmn2102100E) coll 26 October 1994 by M Coke SAM A41300 two malesKangela rainpoolN2 near Mtubatuba (28plusmn2200000S 32plusmn1103600E) coll 25 October 1994 by M Cokeand SAM A41211 one male Ntambanana (Ntrabanana) Zululand coll by H H Curson

Type locality mdash South Africa KwaZulu-Natal Barringtonia and Ficus swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S32plusmn2401800E)

Distribution mdash At present known only from the swamp forests (characterizedby Barringtonia racemosa Syzygium cordatum and Ficus trichopoda vegetationand spongy hydromorphic peat-soil) in the vicinity of Richards Bay Empangeniand the Mapelane Nature Reserve It is probable that the distribution of the speciesmay extend into low-lying areas to the east of the Drakensberg escarpment in theprovince of Mpumalanga and into Mozambique

Etymology mdash From the Latin ldquolividusrdquo meaning ldquobluerdquo or ldquolight bluerdquoreferring to the characteristic silver-blue sheen of the carapace The epitheton isan adjective agreeing in gender with the (masculine) generic name

POTAMONAUTES LIVIDUS NOV 153

Fig 6 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A wholeanimal dorsal aspect B whole animal ventral aspect C cephalothorax frontal aspect

Diagnosis mdash Carapace distinctly vaulted and relatively narrow posteriorlyEpibranchial teeth absent and anterolateral margin of the carapace smooth Post-frontal crest indistinct medially with frontal lobe projecting downwards Cara-pace characteristically orange to red with silver-blue sheen Chelipeds and limbs

154 G GOUWS B A STEWART amp P E REAVELL

bright orange to red with lighter cheliped and dactyl tips Chela in ated and highlyarched

Description of male holotype mdash Size Measurements of the holotype and theranges of other specimens are given in table IV

Carapace ( gs 6A C 7A) Carapace and limbs characteristically orange tored with the carapace possessing a silver-blue sheen when alive Preserved spec-imens (70 ethanol) appear less orange and the carapace retains a blue-greycolour Cephalothorax ovoid distinctly vaulted branchial region highly convex( g 6A C) maximum height and width at anterior third (ratio CHCL D 065CWWCL D 145) Anterior margin straight Urogastric grooves moderately wellde ned Cardiac grooves shallow and poorly de ned Carapace otherwise smoothPostfrontal crest smooth curves forward medially Postfrontal crest diminishesabove inner orbit margins though well de ned immediately lateral to forked mid-point groove by means of two indentations anterior to crest indicating epigas-tric lobes Exorbital teeth moderately sharp but small Epibranchial teeth ab-sent Anterolateral margin posterior to postfrontal crest smooth margin curvingin over carapace in branchial region though indistinctly Each ank has a longitu-dinal groove dividing the subhepatic from the pterygostomial region with verticalgroove running from longitudinal groove joining anterolateral margin between ex-orbital tooth and postfrontal crest

Sternites ( gs 6B 7B) Sternites 1 and 2 fused no suture visible First suture(sternal groove) between sternites 2 and 3 complete Second sternal groove

TABLE IVPotamonautes lividus sp nov wet weight (in g) and measurements (in mm) for the male holotype

and ranges for other individuals examined (maximum of 77 males and 70 females)

Variable Abbreviation Holotype Males Females

Wet weight WW 242 05-214 07-183Carapace length CL 255 84-247 89-276Carapace widest width CWW 370 114-360 118-373Carapace posterior width CWP 281 90-269 86-306Distance between postfrontal crest

and anterior margin PFCD 43 12-222 15-46Distance between orbits ED 114 42-119 43-123Distance between exorbital teeth CWA 259 96-254 96-262Carapace height CH 165 48-171 50-162Width of sixth abdominal segment AW6 75 28-74 31-240Major cheliped propodus length MCPL 427 71-402 76-291Major cheliped propodus height MCPH 198 28-189 28-142Pereopod 2 merus length P2ML 189 50-181 51-171Pereopod 2 merus width P2MW 58 19-56 18-59

POTAMONAUTES LIVIDUS NOV 155

Fig 7 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A carapaceoutline B thoracic sternum C right cheliped dactylus and propodus D left cheliped dactylusand propodus E left third maxilliped F left mandible and mandibular palp posterior view G leftmandibular palp posterior view H left mandibular palp anterior view I left gonopod 1 anteriorview J terminal segment left gonopod 1 anterior view K left gonopod 1 posterior view L leftgonopod 2 anterior view Scale lines represent 1 mm except for A-D where they represent 10 mm

156 G GOUWS B A STEWART amp P E REAVELL

between sternites 3 and 4 complete laterally becoming shallower mediallysloping sharply towards abdominopelvic region

Third maxillipeds ( gs 6C 7E) Filling entire buccal frame except for ovalefferent respiratory openings short agellum present on exopods ischium smoothwith moderately deep vertical groove

Mandibular palp ( g 7F G H) Mandibular palp with two segments terminalsegment undivided with a dense tuft of setae on posterior surface of angeof terminal segment Margins generally hirsute Subterminal segment slightlyenlarged distally

Chelipeds and walking legs ( gs 6A 7C D) Chelipeds markedly unequaldactylus of right cheliped strongly arched 163 times length of dactylus of leftcheliped Both dactyli armed with up to 20 cutting teeth three to four of whichare slightly larger and more prominent Propodus of right cheliped markedlyin ated 168 times longer and 20 times wider than that of left cheliped Pollexpossesses 20 cutting teeth four to ve of which are more prominent Carpi ofboth chelipeds possess one prominent and three rudimentary teeth Margins ofmeri granulose small blunt spine on anterior surface no spine on anterior-inferiormargin Pereopods generally slender (pereopod 2 merus length width D 328 andpereopod 5 merus lengthwidth D 271) P3 longest P5 shortest ventral marginsof propodi and meri smooth dorsal margin with ne sharp bristles dactyli endingin sharp points with margins bearing a series of sharp spinelike bristles

Pleon ( gs 6B 7B) First ve segments broad and short last two segmentslonger terminal segment rounded at distal end

Pleopods ( g 7I J K) Pleopod 1 (gonopod 1) terminal segment short 025times length of subterminal segment terminal segment curves away from mid-line when viewed posteriorly widest at base ending in pointed tip Subterminalsegment of pleopod 1 tapers distally inner lateral margin slightly irregular outerlateral margin straighter both margins hirsute Posterior surface with twisting lon-gitudinal groove extending length of subterminal and terminal segment Groovenot visible on anterior surface Posterior surface and margins of groove hirsutePleopod 2 (gonopod 2) terminal segment lament-like 05 the length of subter-minal segment curving slightly towards medial line proximally curves away frommedial line distally ( g 7L) Subterminal segment widest at base tapering sharplyinwards at 04 of length forms narrow process supporting terminal segment

Variation mdash All individuals are characteristically dark orange to red witha silver-blue sheen to the carapace while the chelipeds vary in colour frombright orange-red to a lighter yellow-orange All individuals are characterized byhighly vaulted carapaces and downwardly projecting frontal lobes The postfrontalcrest which is most pronounced laterally (from directly above the orbits to theanterolateral margin) and incomplete medially is often more distinct in the smaller

POTAMONAUTES LIVIDUS NOV 157

individuals Chelipeds are not always typically arched enclosing a large ovoidspace as in the holotype Chelipeds of smaller individuals although in ated areless arched and often tight closing with the small cutting teeth more obviousChelipeds of females and small males in particular from the Mdibi and Universityof Zululand localities have propodi that are relatively high with in ated palmsand relatively short tightly closing chelae which project slightly downwardsHeterochely has been demonstrated in most Potamonautes-species occurring inSouth Africa (Siegfried 1972 Raubenheimer 1986 Stewart et al 1995 Stewart1997a b Stewart amp Cook 1998 Daniels et al 1998a Gouws et al 2000) Withinthe species 76 of the specimens were right-handed with 11 being left-handedand 13 being of equal or subequal (differing by less than one millimeter) sizeOf the males 79 were right-handed 8 left-handed and 13 equal or subequalFemales had 74 right-handedness 13 left-handedness and in 13 of caseschelipeds were equal or subequal The abdomen of mature females completelyoverlaps the coxae of the pereopods The smallest mature female had a CL of167 mm with the largest immature female having a CL of 159 indicating that thepubertal moult occurs approximately between the 14 mm and 18 mm size classes

Remarks mdash Potamonautes lividus sp nov can readily be distinguished from theten other species in the genus Potamonautes known to occur within South AfricaPotamonautes warreni Calman 1918 P dentatus P parvispina and P unispinusall bear a singular spine or a series of teeth on the anterolateral margins whereasP lividus sp nov is smooth Potamonautes perlatus P sidneyi and P granularisare all larger crabs with in ated arched carapaces with complete distinct post-frontal crests and scabrosity or granulation of the anterior margins orbits epi-branchial corners or postfrontal crests Potamonautes lividus sp nov has smoothcarapace margins and a incomplete postfrontal crest The terminal segment ofgonopod 1 in P lividus sp nov is relatively short and triangular and curves awayfrom the medial line when viewed posteriorly while that of P sidneyi is relativelylonger more slender and more S-shaped The postfrontal crest of P sidneyi mayjoin the anterolateral margin at a relatively sharp angle and form a pronouncedepibranchial corner along the anterolateral margin The anterolateral margin inP lividus sp nov is more rounded and the epibranchial corners slope down to-wards the anks Potamonautes granularis is chocolate brown with orange tips tothe chelipeds Potamonautes brincki is a smaller crab with a smoother carapacethough also chocolate to reddish-brown in colour with a nely granulated antero-lateral margin which does not curve in over the carapace in the branchial region(Stewart 1997b) Potamonautes depressus and P clarus both have rounded epi-branchial corners and smooth carapaces though these are relatively shallow andhave attened dorsal surfaces Both are characterized by long slender limbs Pota-monautes depressus is brown to green-brown in colour while P clarus is brightorange in colour

158 G GOUWS B A STEWART amp P E REAVELL

A number of species from further a eld bear a super cial resemblance toP lividus sp nov particularly with regard to carapace morphology though in mostcases they can be readily distinguished Potamonautes pilosus Hilgendorf 1898 isknown from East Africa and is a small crab with a CWW of less than 25 mmSpecimens possess a weak postfrontal crest which along with the anterolateralmargin can be granulated (Hilgendorf 1898 Bott 1955) Potamonautes neumanniHilgendorf 1898 is known from East Africa and has a characteristically vaultedcarapace without a complete distinct postfrontal crest (Hilgendorf 1898 Bott1955) The postfrontal crest is more distinct in P lividus particularly laterally andthe exorbital teeth are sharper and more de ned in P lividus than in P neumanniThe terminal segment of gonopod 1 is longer and more slender in P neumannithan in P lividus and curves distinctly outwards The subterminal segment ofgonopod 1 is wider at its apex in P neumanni than in P lividus Additionally thecarapace of preserved specimens of P neumanni is typically grey in colour whileliving specimens are violet in colour with bright olive-green limbs and chelipeds(Hilgendorf 1898) Potamonautes ballayi acristatus Bott 1955 has an incompletepostfrontal crest only present above the orbits and small and blunt exorbital teethThe major chela although highly arched and the minor chela are long and moreslender than those of P lividus sp nov The terminal segment of gonopod 1 ofP granviki Colosi 1924 is curved towards the medial line when viewed posteriorly(Bott 1955) The chelae of both P berardi berardi Audouin 1826 and P b ignestiiParisi 1923 are relatively short and high with stout downward-projecting ngersThe anterior margin of the frontal lobe of P b berardi shows a distinct invaginationand the anterolateral margin appears sharp and less rounded than in P lividus spnov while the postfrontal crest of P b ignestii is complete and has a fairly longmedial groove Potamonautes emini emini Hilgendorf 1892 are generally smallcrabs with a less in ated carapace and short stout chelipeds The subterminaland terminal segments of gonopod 1 are of more or less equal size (Bott 1955)Potamonautes e semilunaris Bott 1955 and P luashiensis Bott 1955 are alsosmall crabs (CWW lt 20 mm) with the postfrontal crest only visible laterally andin the case of P luashiensis the anterolateral margin and postfrontal crest mayshow granulation Potamonautes didieri Rathbun 1904 possesses a more completerounded postfrontal crest and shorter more stout chelipeds (Bott 1955)

ACKNOWLEDGEMENTS

Financial assistance was kindly provided by the World Wildlife Fund - SouthAfrica the Foundation for Research Development and the University of ZululandThe KwaZulu-Natal Nature Conservation Services provided accommodation and

POTAMONAUTES LIVIDUS NOV 159

logistic support Liz Hoenson Peter Cook Mike Coke and Tyrone Ridgway arethanked for assistance in the eld and Michelle van der Merwe is thanked foraiding in the photography and drafting of gures The authors wish to thank ananonymous reviewer for comments on the manuscript

REFERENCES

BARNARD K H 1935 Scienti c results of the Vernay-Lang Kalahari expedition March toSeptember 1930 Crustacea Ann Transvaal Mus 16 481-492

mdash mdash 1950 Descriptive catalogue of South African decapod Crustacea (crabs and shrimps) AnnSouth African Mus 38 1-837

BOCK W J 1986 Species concepts speciation and macroevolution In K IWATSUKIP H RAVEN amp W J BOCK (eds) Modern aspects of species 31-57 (University of TokyoPress Tokyo)

BOTT R 1955 Die Suumlsswasserkrabben von Afrika (Crust Decap) und ihre StammesgeschichteAnn Mus R Congo Belge (C Zool) 1 (33) 209-352 pls 1-30

BRUTON M N 1980 An outline of the ecology of the Mgobezeleni lake system at Sodwana withemphasis on the mangrove community In M N BRUTON amp K H COOPER (eds) Studieson the ecology of Maputaland 408-426 (Rhodes University Grahamstown)

CUMBERLIDGE N 1986 Ventilation of the branchial chambers in the amphibious West Africanfreshwater crab Sudanonautes (Convexonautes) aubryi monodi (Balss 1929) (BrachyuraPotamonautidae)Hydrobiol 134 53-65

mdash mdash 1991 The respiratory system of Globonautes macropus (Rathbun 1898) a terrestrialfreshwater crab from Liberia (GecarcinucoideaGecarcinucidae)Crustaceana 61 (1) 69-80

DANIELS S R B A STEWART amp M J GIBBONS 1998a Potamonautes granularis sp nov(Brachyura Potamonautidae) a new cryptic species of river crab from the Olifants Riversystem South Africa Crustaceana 71 (8) 885-903

mdash mdash mdash mdash amp mdash mdash 1998b Genetic and morphometric variation in the potamonautid river crabPotamonautes parvispina (Decapoda Potamonautidae) from two Western Cape rivers SouthAfrica Journ nat Hist London 32 1245-1258

mdash mdash mdash mdash amp mdash mdash 1999 Genetic structure among populations of Potamonautes perlatus(Decapoda Potamonautidae) from the Olifants River system in the Western Cape SouthAfrica Journ Zool London 249 (2) 137-142

DIacuteAZ H amp G RODRIacuteGUEZ 1977 The branchial chamber in terrestrial crabs a comparative studyBiol Bull Woods Hole 153 485-504

GOUWS G B A STEWART amp M COKE 2000 Evidence for a new species of river crab(Decapoda Brachyura Potamonautidae) from the Drakensberg South Africa Journ CrustBiol 20 (4) 743-758

GREENAWAY P amp H H TAYLOR 1976 Aerial gas exchange in Australian arid-zone crabParathelphusa transversa Von Martens Nature London 262 711-713

HILGENDORF F 1898 Die Land- und Suumlsswasser-Dekapoden Ostafrikas Die Thierwelt DeutschOst-Afrikas 4 (7) 1-37

LENZ H 1912 Afrikanische Crustaceen aus schwedischen Sammlungen Ark Zool 7 (29) 1-10MARKERT C L amp I FAULHABER 1965 Lactate dehydrogenase isozyme patterns of sh Journ

exp Zool 159 319-332MAYR E 1963 Animal species and evolution i-xiv 1-797 (Harvard University Press Cambridge

Massachusetts)mdash mdash 1970 Populations species and evolution i-xv 1-453 (Harvard University Press Cambridge

Massachusetts)

POTAMONAUTES LIVIDUS NOV 143

TABLE IIDistribution of allele frequencies at nine polymorphic loci in six populations of Potamonautes spp

studied N D sample size refer to table I for enzyme abbreviations

Population

Locus Zululand A Mdibi Mapelane Zululand B Dakaneni Manzibomvu

IDH-2N 41 24 25 13 25 13120 0012 0729 0380 0000 0000 000080 0988 0229 0000 1000 1000 100045 0000 0043 0620 0000 0000 0000

GPIN 56 26 25 13 25 13165 0045 0000 0000 0000 0000 0000150 0000 0000 0000 0000 0000 0038100 0000 0000 0000 0000 0000 003840 0938 1000 1000 0962 0880 0846

iexcl80 0018 0000 0000 0038 0120 0077

HEXN 41 26 25 13 25 13100 1000 1000 1000 0000 0000 000095 0000 0000 0000 1000 1000 1000

MDH-1N 41 26 25 13 25 13100 0988 1000 1000 1000 1000 100090 0012 0000 0000 0000 0000 0000

MDH-2N 41 26 25 13 25 13100 1000 1000 1000 0962 0960 100075 0000 0000 0000 0000 0040 000065 0000 0000 0000 0038 0000 0000

IDH-1N 41 26 25 13 23 7150 0000 0000 0000 1000 0891 0929135 1000 1000 1000 0000 0109 0071

LT-2N 41 26 25 13 25 13250 0049 0019 0020 0000 0000 0000100 0854 0885 0840 0923 0980 0769

0 0098 0096 0140 0077 0020 0231

PGM-1N 52 26 25 13 25 13110 0365 0000 0000 0000 0000 0000100 0212 0000 0000 0038 0140 003890 0423 1000 1000 0923 0800 096275 0000 0000 0000 0038 0060 0000

(continued overleaf)

144 G GOUWS B A STEWART amp P E REAVELL

TABLE II(Continued)

Population

Locus Zululand A Mdibi Mapelane Zululand B Dakaneni Manzibomvu

GLN 41 26 25 13 25 1390 1000 0962 1000 1000 1000 100075 0000 0038 0000 0000 0000 0000

PGM-2N 56 26 25 13 25 13100 1000 1000 1000 0000 0040 000075 0000 0000 0000 1000 0960 1000

PHPN 41 26 25 13 25 13105 1000 0808 1000 1000 1000 100090 0000 0192 0000 0000 0000 0000

LGG-2N 41 26 25 13 24 13100 0854 0942 1000 0846 0979 069290 0146 0058 0000 0154 0021 0308

Genetic variability was low in all populations The percentage polymorphicloci (no criterion) ranged from 95 to 333 in the Mapelane and Dakanenipopulations respectively The mean unbiased expected heterozygosity varied from0034 (in the University of Zululand B population) to 0063 (in the Universityof Zululand A and Manzibomvu populations) The mean number of alleles perlocus ranged from 11 (in the Mapelane population) to 14 (in the Dakaneni andUniversity of Zululand A populations)

The dendrogram constructed based on the genetic identity values obtained bypairwise comparison of populations (table III) clearly distinguished two clusters( g 2) The group representing the form A populations clearly separated from thegroup representing the form B (Potamonautes sidneyi) populations at a geneticidentity value of I D 0829 D D 0187 Three loci contributed signi cantly tothis separation one of them diagnostically The HEX locus showed a xed alleledifference between the individuals of the two forms with the form A individualsbeing xed for the allele HEX100 and the form B (P sidneyi) individuals xed forthe HEX95 allele Strong heterogeneity was observed between the populations ofthe two forms at the IDH-1 and PGM-2 loci With the exception of one individualin the Dakaneni population having a homozygote with the PGM-2100 allele form Aand form B were characterized by the xation of alleles PGM-2100 and PGM-275

POTAMONAUTES LIVIDUS NOV 145

TABLE IIICoef cient matrix of Neirsquos (1978) unbiased genetic identity (above diagonal) and unbiased geneticdistance (below diagonal) for pairwise comparisons of the six populations of Potamonautes studied

Population

Zululand A Mdibi Mapelane Zululand B Dakaneni Manzibomvu

Zululand A currencurrencurrencurrencurren 0958 0949 0840 0855 0842

Mdibi 0043 currencurrencurrencurrencurren 0986 0821 0832 0822

Mapelane 0052 0014 currencurrencurrencurrencurren 0813 0825 0814

Zululand B 0174 0197 0206 currencurrencurrencurrencurren 0998 0999

Dakaneni 0157 0184 0193 0002 currencurrencurrencurrencurren 0994

Manzibomvu 0172 0196 0206 0001 0006 currencurrencurrencurrencurren

Fig 2 UPGMA dendrogram constructed from the matrix of Neirsquos (1978) unbiased genetic identi-ties (I ) using allozyme data from 21 loci

respectively Identity-values for within form comparisons varied from 0949 to0986 (D D 0014 to 0052) and 0994 to 0999 (D D 0001 to 0006) for form Aand form B respectively

Morphometric analysis mdash Individuals from the form A populations couldeasily be distinguished from the form B (P sidneyi) individuals by the possessionof a much more vaulted carapace in ated chelipeds a postfrontal crest whichdiminishes medially and the characteristic silver-blue carapace sheen and brightorange to red chelipeds and pereopods Mature form B (P sidneyi) individualsfrequently attained a larger size class (with CL being representative of size) thandid the mature form A individuals

146 G GOUWS B A STEWART amp P E REAVELL

Three carapace variables (ED CH and CWP) contributed signi cantly to thediscrimination between the two forms in the discriminant function analysis Thehistogram plot of observed canonical variable scores ( g 3) clearly separates thetwo forms with the canonical variable means of the form A and form B individualscalculated at iexcl0996 and 1965 respectively The classi cation function (the linearfunction of variables which best discriminates the individuals of one group fromthe other speci ed groupings) was calculated for individuals of each form Theclassi cation function of the form A group was

Y D 306704 (Log CWP) iexcl 26103 (Log ED) iexcl 228513 (Log CH) iexcl 64156

and of the form B (P sidneyi) group

Y D 35097 (Log ED) iexcl 315543 (Log CH) C 347231 (Log CWP) iexcl 88367

Using the classi cation functions individuals were reassigned to groups basedon highest a posteriori probabilities Of the form A individuals 9437 (134of 142) were correctly classi ed with eight individuals being reassigned to theform B group Of the form B individuals 8889 were correctly reassigned to theP sidneyi group with eight of the 72 individuals being reassigned to the form Agroup

Fig 3 Histogram of scores for specimens of Potamonautes lividus sp nov (form A) and P sidneyiRathbun 1904 (form B) along the canonical variable calculated from a discriminant function

analysis using seven carapace variables

POTAMONAUTES LIVIDUS NOV 147

Comparison of regressions of the most discriminating variables between the twoforms regressed over CL in turn also showed signi cant differences between thetwo forms CH regressed over CL showed highly signi cant differences betweenthe two forms (SS D 0011 df D 1 F D 31266 P lt 0001) as did ED(SS D 0011 df D 1 F D 8333 P lt 0005) and CWP (SS D 0006 df D 1F D 8136 P lt 0005) These represent the most discriminating variables andtheir regressions are represented graphically ( g 4a b c) PFCD (SS D 0199df D 1 F D 52671 P lt 0001) CWW (SS D 0003 df D 1 F D 30963P lt 0001) and CWA (SS D 0001 df D 1 F D 6182 P lt 002) also showedthat there were signi cant differences between the two forms but the discriminantfunction analysis showed them to be redundant in constructing the model

Qualitative analysis mdash Examination of gonopods and mouthparts revealed onlyslight differences in gonopod morphology The terminal segment of gonopod 1of the undescribed form was relatively short and triangular whereas the terminalsegment of gonopod 1 of P sidneyi appears to be substantially longer and moreslender Although the terminal segment is bent away from the medial line in bothforms the terminal segment in P sidneyi possesses a lobe or ange that extendsinwards giving the terminal segment an S-shaped appearance The gonopods andmandibular palps of the two forms are illustrated in g 5

DISCUSSION

The data presented above clearly indicate that the two forms of freshwatercrabs from KwaZulu-Natal are distinct The form A specimens are smaller with amore vaulted carapace that is relatively narrower posteriorly and that possessesa relatively narrower frontal lobe (ED) than that of the Potamonautes sidneyiindividuals

Not only are the two forms clearly distinct both biochemically and morpho-logically but strong evidence suggests that they are reproductively isolated Thepresence of a diagnostic locus HEX xed for alternate alleles in the sympatricpopulation of the two forms indicates that a lack of gene ow and thus repro-ductive isolation exist between the two forms This allows for species recognitionunder the Biological Species Concept (Mayr 1970) under which species are de- ned as ldquogroups of actually or potentially interbreeding populations which arereproductively isolated from other such groupsrdquo (Mayr 1963 19) or ldquogeneticallyisolated (in nature) from other such groupsrdquo (Bock 1986 33) In his model of al-lopatric speciation Bock (1986) suggested that newly evolved species in sympatrywould exert mutually selective demands on each other by means of reproductive

148 G GOUWS B A STEWART amp P E REAVELL

Fig 4 Comparisons of the regressions of (A) Log CH (carapace height) over Log CL (carapacelength) (B) Log ED (eye distance) over Log CL and (C) Log CWP (posterior carapace width) overLog CL between form A (Potamonautes lividus sp nov) and form B (P sidneyi Rathbun 1904) All

differences are signi cant (at the P lt 0005 level)

POTAMONAUTES LIVIDUS NOV 149

Fig 5 A-E form A (Potamonautes lividus sp nov composite of male holotype SAM A43540and unaccessioned material) A carapace outline B left mandibular palp anterior view C leftmandibular palp posterior view D left gonopod 1 anterior view and E left gonopod 1 posteriorview F-J form B (Potamonautes sidneyi Rathbun 1904 unaccessioned specimen) F carapaceoutline G left mandibular palp anterior view H left mandibular palp posterior view I left

gonopod 1 anterior view J left gonopod 1 posterior view

150 G GOUWS B A STEWART amp P E REAVELL

interference and ecological competition This would lead to a divergence of mor-phological and behavioural aspects of feeding reproduction and other ecologicalfeatures The different gonopod morphologies of the two forms may re ect this

The three form A populations clustered separately from the three P sidneyipopulations at a I -value of 0829 Stewart (1997a) calculated the separationI -value between P parvispina Stewart 1997 and P perlatus H Milne Edwards1837 to be 068 An I -value of 066 separated both P perlatus and P brinckiBott 1960 in the Western Cape (Stewart 1997b) and P unispinus Stewart ampCook 1998 and P sidneyi in Mpumalanga (Stewart amp Cook 1998) An I -valueof 0599 was obtained separating P clarus Gouws Stewart amp Coke 2000 andP depressus (Gouws et al 2000) The only species in the genus delineated using ahigher I -value was P granularis Daniels Stewart amp Gibbons 1998 which wasseparated from P perlatus in the Olifants River at a I -value of 088 (Danielset al 1998a 1999) Although slightly higher than most interspeci c values inthe genus the value obtained in this study nevertheless falls within the range (035to 085) speci ed by Thorpe (1982) to indicate congeneric species differencesAllopatric populations showing I -values of less than 085 are unlikely to beconspeci c (Thorpe amp Soleacute-Cava 1994) With the exception of two cases allpairwise comparisons between allopatric populations of the two forms yieldedI -values less than 085

Identity-values were high for comparisons within both the form A (0949 to0986) and P sidneyi (0994 to 0999) groups Intraspeci c I -values are generallyhigh in the genus Potamonautes and disjunct populations within a species tendto be genetically undifferentiated Intraspeci c I -values obtained in six studies(Stewart 1997a b Stewart amp Cook 1998 Daniels et al 1998b 1999) involvingsix Potamonautes species varied from 0902 to 1000 (D D 0000 to 0103)An intraspeci c I -value of 075 was obtained in a comparison of two groups ofP brincki populations across the Cape Peninsula and Cape Flats However thismost probably indicates a species difference and requires further investigation(Stewart 1997b) Given the high intraspeci c I -values characteristic of the genusand those obtained for comparisons within each form the I -value obtainedfor the comparison between the two forms most likely represents a speciesdifference

Bock (1986) also de ned a species as possessing a set of three distinctcharacteristics genetic unity reproductive unity and ecological unity Biochemicaldata provide support for compliance with the rst two criteria for both formsWhile no empirical evidence is as yet available con rming the third factor adegree of macro- and microhabitat segregation and thus ecological segregationis evident between the two forms Potamonautes sidneyi is widespread acrossthe province (Stewart et al 1995) while the other form appears to have a

POTAMONAUTES LIVIDUS NOV 151

more limited distribution in northeastern KwaZulu-Natal restricted to patches ofswamp forest with particular oral assemblages The swamp forests are oftencharacterized by Barringtonia racemosa Syzygium cordatum Ficus trichopodaHibiscus tiliaceus L Rauvola caffra Sond Voacanga thouarsii Roem amp SchultRaphia australis Oberm amp Strey and Podocarpus falcatus (Thunb) R Br exMirb with the fern Stenochlaena tenuifolia (Desv) T Moore often present in theunderstorey (Bruton 1980 Moll 1980) Within the swamp forests the sympatricpopulations appear to show a degree of microhabitat segregation Observationssuggest that P sidneyi has a closer association with water as individuals were nevercollected great distances away from seepage pools and channels owing throughthe forest Conversely individuals of the swamp-forest form were most oftencollected farther from water and their burrows were often among the vegetationObservations suggest that this form is more terrestrial Individuals were noticedto move to higher elevations when the water table rose through the hydromorphicpeat soil ooding their burrows and the surface and they were also more active oncloudy overcast days Evidence of terrestrial adaptation is most likely to be foundin the structure and histology of the organs and tissues involved in respirationfactors such as branchial chamber shape and volume gill structure and formulaand the structure and vascularization of the branchiostegite lining are knownto re ect changes brought upon by the constraints of the terrestrial environment(Greenaway amp Taylor 1976 Diacuteaz amp Rodriacuteguez 1977 Taylor amp Greenaway1979 Cumberlidge 1986 1991 Takeda et al 1996) Although the availabilityof material prohibited the investigation of this aspect future research may prove tobe fruitful and highlight a greater distinction between the two forms

Studies on terrestrial adaptation supplemented by behavioural data that couldillustrate microhabitat and ecological segregation would quantify further thedegree of differentiation between the two forms However two independent datasets biochemical and morphological present strong evidence for the speci c statusof the swamp-forest form

TAXONOMY

Potamonautes lividus sp nov ( gs 6-7)

Material examined mdash Holotype South African Museum (SAM) A43540 one male CL D255 mm Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws andL Hoenson Allotype SAM A43541 one female CL D 245 mm Ficus and Barringtonia swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S 32plusmn2401800E)coll 27 January 1997 by B A Stewart G Gouws and L Hoenson Other material SAM A43542two males Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws

152 G GOUWS B A STEWART amp P E REAVELL

and L Hoenson SAM A43543 one female Lake Nhlabane north of Richards Bay (28plusmn3800500S32plusmn1601700E) coll 27 April 1993 by the University of Zululand Zoology Department SAMA43544 three males one female Mdibi swamp forest along Mdibi stream 8 km north of RichardsBay (28plusmn4202400S 32plusmn0902600E) coll 26 January 1997 by B A Stewart P A Cook M CokeP E Reavell G Gouws and L Hoenson SAM A43545 one male one female Syzygium forestUniversity of Zululand campus (28plusmn5102500S 31plusmn5100200E) coll 24 January 1997 by B A StewartP A Cook P E Reavell G Gouws and L Hoenson SAM A43546 two males two femalesUniversity of Zululand stream owing through campus (28plusmn550S 31plusmn410E) coll 10 September 1995by P E Reavell SAM A41313 one male one female swamp forest Empangeni (28plusmn5102500S31plusmn5100200E) coll 2 August 1994 by M Coke SAM A41155 one male University of ZululandSyzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S 31plusmn450E) coll 10 December1988 by P E Reavell SAM A41153 three males smaller holes in hydromorphic soil Syzygiumcordatum swamp forest University of Zululand (28plusmn450S 31plusmn450E) coll 20 March 1994 byP E Reavell SAM A41156 one female Syzygium cordatum swamp forest University of Zululand(28plusmn450S 31plusmn450E) coll 18 May 1992 by P E Reavell SAM A41154 one male one femaleUniversity of Zululand Syzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S31plusmn450E) coll 10 May 1990 by P E Reavell SAM A43547 two males one female swamp forestUniversity of Zululand (28plusmn450S 31plusmn450E) coll 1 April 1994 by P E Reavell SAM A43548one male one female Syzygium and Bridelia dominated swamp forest University of Zululand(28plusmn5102500S 31plusmn5100200E) coll 7 October 1996 by P E Reavell SAM A43549 one female Mdibiswamp forest Lake Msingazi catchment area north of Richards Bay (28plusmn420S 32plusmn090E) coll5 December 1996 by P E Reavell Albany Museum mdash GEN910 one female Mpolozi swampsMapelane (28plusmn2601300S 32plusmn2402500E) coll 13 February 1991 Albany Museum mdash GEN965 twomales ve females NrsquoKoninga Valley Richards Bay (28plusmn450S 32plusmn030E) coll 7 April 1988

Other material mdash The following specimens included in the collections of the South AfricanMuseum warrant further investigation as although they bear some resemblance to the speciesdescribed below their identi cation is uncertain SAM A41276 one male one female Mbonenidam Mkuze Game Reserve (27plusmn3705700S 32plusmn1504500E) coll 28 October 1994 by M Coke SAMA41299 two males Nxwala stream Mkuze Game Reserve (27plusmn4302300S 32plusmn1601000E) coll 10November 1994 by O Bourquin SAM A41277 one male Rainpool south of entrance False BayPark (28plusmn0000100S 32plusmn2102100E) coll 26 October 1994 by M Coke SAM A41300 two malesKangela rainpoolN2 near Mtubatuba (28plusmn2200000S 32plusmn1103600E) coll 25 October 1994 by M Cokeand SAM A41211 one male Ntambanana (Ntrabanana) Zululand coll by H H Curson

Type locality mdash South Africa KwaZulu-Natal Barringtonia and Ficus swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S32plusmn2401800E)

Distribution mdash At present known only from the swamp forests (characterizedby Barringtonia racemosa Syzygium cordatum and Ficus trichopoda vegetationand spongy hydromorphic peat-soil) in the vicinity of Richards Bay Empangeniand the Mapelane Nature Reserve It is probable that the distribution of the speciesmay extend into low-lying areas to the east of the Drakensberg escarpment in theprovince of Mpumalanga and into Mozambique

Etymology mdash From the Latin ldquolividusrdquo meaning ldquobluerdquo or ldquolight bluerdquoreferring to the characteristic silver-blue sheen of the carapace The epitheton isan adjective agreeing in gender with the (masculine) generic name

POTAMONAUTES LIVIDUS NOV 153

Fig 6 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A wholeanimal dorsal aspect B whole animal ventral aspect C cephalothorax frontal aspect

Diagnosis mdash Carapace distinctly vaulted and relatively narrow posteriorlyEpibranchial teeth absent and anterolateral margin of the carapace smooth Post-frontal crest indistinct medially with frontal lobe projecting downwards Cara-pace characteristically orange to red with silver-blue sheen Chelipeds and limbs

154 G GOUWS B A STEWART amp P E REAVELL

bright orange to red with lighter cheliped and dactyl tips Chela in ated and highlyarched

Description of male holotype mdash Size Measurements of the holotype and theranges of other specimens are given in table IV

Carapace ( gs 6A C 7A) Carapace and limbs characteristically orange tored with the carapace possessing a silver-blue sheen when alive Preserved spec-imens (70 ethanol) appear less orange and the carapace retains a blue-greycolour Cephalothorax ovoid distinctly vaulted branchial region highly convex( g 6A C) maximum height and width at anterior third (ratio CHCL D 065CWWCL D 145) Anterior margin straight Urogastric grooves moderately wellde ned Cardiac grooves shallow and poorly de ned Carapace otherwise smoothPostfrontal crest smooth curves forward medially Postfrontal crest diminishesabove inner orbit margins though well de ned immediately lateral to forked mid-point groove by means of two indentations anterior to crest indicating epigas-tric lobes Exorbital teeth moderately sharp but small Epibranchial teeth ab-sent Anterolateral margin posterior to postfrontal crest smooth margin curvingin over carapace in branchial region though indistinctly Each ank has a longitu-dinal groove dividing the subhepatic from the pterygostomial region with verticalgroove running from longitudinal groove joining anterolateral margin between ex-orbital tooth and postfrontal crest

Sternites ( gs 6B 7B) Sternites 1 and 2 fused no suture visible First suture(sternal groove) between sternites 2 and 3 complete Second sternal groove

TABLE IVPotamonautes lividus sp nov wet weight (in g) and measurements (in mm) for the male holotype

and ranges for other individuals examined (maximum of 77 males and 70 females)

Variable Abbreviation Holotype Males Females

Wet weight WW 242 05-214 07-183Carapace length CL 255 84-247 89-276Carapace widest width CWW 370 114-360 118-373Carapace posterior width CWP 281 90-269 86-306Distance between postfrontal crest

and anterior margin PFCD 43 12-222 15-46Distance between orbits ED 114 42-119 43-123Distance between exorbital teeth CWA 259 96-254 96-262Carapace height CH 165 48-171 50-162Width of sixth abdominal segment AW6 75 28-74 31-240Major cheliped propodus length MCPL 427 71-402 76-291Major cheliped propodus height MCPH 198 28-189 28-142Pereopod 2 merus length P2ML 189 50-181 51-171Pereopod 2 merus width P2MW 58 19-56 18-59

POTAMONAUTES LIVIDUS NOV 155

Fig 7 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A carapaceoutline B thoracic sternum C right cheliped dactylus and propodus D left cheliped dactylusand propodus E left third maxilliped F left mandible and mandibular palp posterior view G leftmandibular palp posterior view H left mandibular palp anterior view I left gonopod 1 anteriorview J terminal segment left gonopod 1 anterior view K left gonopod 1 posterior view L leftgonopod 2 anterior view Scale lines represent 1 mm except for A-D where they represent 10 mm

156 G GOUWS B A STEWART amp P E REAVELL

between sternites 3 and 4 complete laterally becoming shallower mediallysloping sharply towards abdominopelvic region

Third maxillipeds ( gs 6C 7E) Filling entire buccal frame except for ovalefferent respiratory openings short agellum present on exopods ischium smoothwith moderately deep vertical groove

Mandibular palp ( g 7F G H) Mandibular palp with two segments terminalsegment undivided with a dense tuft of setae on posterior surface of angeof terminal segment Margins generally hirsute Subterminal segment slightlyenlarged distally

Chelipeds and walking legs ( gs 6A 7C D) Chelipeds markedly unequaldactylus of right cheliped strongly arched 163 times length of dactylus of leftcheliped Both dactyli armed with up to 20 cutting teeth three to four of whichare slightly larger and more prominent Propodus of right cheliped markedlyin ated 168 times longer and 20 times wider than that of left cheliped Pollexpossesses 20 cutting teeth four to ve of which are more prominent Carpi ofboth chelipeds possess one prominent and three rudimentary teeth Margins ofmeri granulose small blunt spine on anterior surface no spine on anterior-inferiormargin Pereopods generally slender (pereopod 2 merus length width D 328 andpereopod 5 merus lengthwidth D 271) P3 longest P5 shortest ventral marginsof propodi and meri smooth dorsal margin with ne sharp bristles dactyli endingin sharp points with margins bearing a series of sharp spinelike bristles

Pleon ( gs 6B 7B) First ve segments broad and short last two segmentslonger terminal segment rounded at distal end

Pleopods ( g 7I J K) Pleopod 1 (gonopod 1) terminal segment short 025times length of subterminal segment terminal segment curves away from mid-line when viewed posteriorly widest at base ending in pointed tip Subterminalsegment of pleopod 1 tapers distally inner lateral margin slightly irregular outerlateral margin straighter both margins hirsute Posterior surface with twisting lon-gitudinal groove extending length of subterminal and terminal segment Groovenot visible on anterior surface Posterior surface and margins of groove hirsutePleopod 2 (gonopod 2) terminal segment lament-like 05 the length of subter-minal segment curving slightly towards medial line proximally curves away frommedial line distally ( g 7L) Subterminal segment widest at base tapering sharplyinwards at 04 of length forms narrow process supporting terminal segment

Variation mdash All individuals are characteristically dark orange to red witha silver-blue sheen to the carapace while the chelipeds vary in colour frombright orange-red to a lighter yellow-orange All individuals are characterized byhighly vaulted carapaces and downwardly projecting frontal lobes The postfrontalcrest which is most pronounced laterally (from directly above the orbits to theanterolateral margin) and incomplete medially is often more distinct in the smaller

POTAMONAUTES LIVIDUS NOV 157

individuals Chelipeds are not always typically arched enclosing a large ovoidspace as in the holotype Chelipeds of smaller individuals although in ated areless arched and often tight closing with the small cutting teeth more obviousChelipeds of females and small males in particular from the Mdibi and Universityof Zululand localities have propodi that are relatively high with in ated palmsand relatively short tightly closing chelae which project slightly downwardsHeterochely has been demonstrated in most Potamonautes-species occurring inSouth Africa (Siegfried 1972 Raubenheimer 1986 Stewart et al 1995 Stewart1997a b Stewart amp Cook 1998 Daniels et al 1998a Gouws et al 2000) Withinthe species 76 of the specimens were right-handed with 11 being left-handedand 13 being of equal or subequal (differing by less than one millimeter) sizeOf the males 79 were right-handed 8 left-handed and 13 equal or subequalFemales had 74 right-handedness 13 left-handedness and in 13 of caseschelipeds were equal or subequal The abdomen of mature females completelyoverlaps the coxae of the pereopods The smallest mature female had a CL of167 mm with the largest immature female having a CL of 159 indicating that thepubertal moult occurs approximately between the 14 mm and 18 mm size classes

Remarks mdash Potamonautes lividus sp nov can readily be distinguished from theten other species in the genus Potamonautes known to occur within South AfricaPotamonautes warreni Calman 1918 P dentatus P parvispina and P unispinusall bear a singular spine or a series of teeth on the anterolateral margins whereasP lividus sp nov is smooth Potamonautes perlatus P sidneyi and P granularisare all larger crabs with in ated arched carapaces with complete distinct post-frontal crests and scabrosity or granulation of the anterior margins orbits epi-branchial corners or postfrontal crests Potamonautes lividus sp nov has smoothcarapace margins and a incomplete postfrontal crest The terminal segment ofgonopod 1 in P lividus sp nov is relatively short and triangular and curves awayfrom the medial line when viewed posteriorly while that of P sidneyi is relativelylonger more slender and more S-shaped The postfrontal crest of P sidneyi mayjoin the anterolateral margin at a relatively sharp angle and form a pronouncedepibranchial corner along the anterolateral margin The anterolateral margin inP lividus sp nov is more rounded and the epibranchial corners slope down to-wards the anks Potamonautes granularis is chocolate brown with orange tips tothe chelipeds Potamonautes brincki is a smaller crab with a smoother carapacethough also chocolate to reddish-brown in colour with a nely granulated antero-lateral margin which does not curve in over the carapace in the branchial region(Stewart 1997b) Potamonautes depressus and P clarus both have rounded epi-branchial corners and smooth carapaces though these are relatively shallow andhave attened dorsal surfaces Both are characterized by long slender limbs Pota-monautes depressus is brown to green-brown in colour while P clarus is brightorange in colour

158 G GOUWS B A STEWART amp P E REAVELL

A number of species from further a eld bear a super cial resemblance toP lividus sp nov particularly with regard to carapace morphology though in mostcases they can be readily distinguished Potamonautes pilosus Hilgendorf 1898 isknown from East Africa and is a small crab with a CWW of less than 25 mmSpecimens possess a weak postfrontal crest which along with the anterolateralmargin can be granulated (Hilgendorf 1898 Bott 1955) Potamonautes neumanniHilgendorf 1898 is known from East Africa and has a characteristically vaultedcarapace without a complete distinct postfrontal crest (Hilgendorf 1898 Bott1955) The postfrontal crest is more distinct in P lividus particularly laterally andthe exorbital teeth are sharper and more de ned in P lividus than in P neumanniThe terminal segment of gonopod 1 is longer and more slender in P neumannithan in P lividus and curves distinctly outwards The subterminal segment ofgonopod 1 is wider at its apex in P neumanni than in P lividus Additionally thecarapace of preserved specimens of P neumanni is typically grey in colour whileliving specimens are violet in colour with bright olive-green limbs and chelipeds(Hilgendorf 1898) Potamonautes ballayi acristatus Bott 1955 has an incompletepostfrontal crest only present above the orbits and small and blunt exorbital teethThe major chela although highly arched and the minor chela are long and moreslender than those of P lividus sp nov The terminal segment of gonopod 1 ofP granviki Colosi 1924 is curved towards the medial line when viewed posteriorly(Bott 1955) The chelae of both P berardi berardi Audouin 1826 and P b ignestiiParisi 1923 are relatively short and high with stout downward-projecting ngersThe anterior margin of the frontal lobe of P b berardi shows a distinct invaginationand the anterolateral margin appears sharp and less rounded than in P lividus spnov while the postfrontal crest of P b ignestii is complete and has a fairly longmedial groove Potamonautes emini emini Hilgendorf 1892 are generally smallcrabs with a less in ated carapace and short stout chelipeds The subterminaland terminal segments of gonopod 1 are of more or less equal size (Bott 1955)Potamonautes e semilunaris Bott 1955 and P luashiensis Bott 1955 are alsosmall crabs (CWW lt 20 mm) with the postfrontal crest only visible laterally andin the case of P luashiensis the anterolateral margin and postfrontal crest mayshow granulation Potamonautes didieri Rathbun 1904 possesses a more completerounded postfrontal crest and shorter more stout chelipeds (Bott 1955)

ACKNOWLEDGEMENTS

Financial assistance was kindly provided by the World Wildlife Fund - SouthAfrica the Foundation for Research Development and the University of ZululandThe KwaZulu-Natal Nature Conservation Services provided accommodation and

POTAMONAUTES LIVIDUS NOV 159

logistic support Liz Hoenson Peter Cook Mike Coke and Tyrone Ridgway arethanked for assistance in the eld and Michelle van der Merwe is thanked foraiding in the photography and drafting of gures The authors wish to thank ananonymous reviewer for comments on the manuscript

REFERENCES

BARNARD K H 1935 Scienti c results of the Vernay-Lang Kalahari expedition March toSeptember 1930 Crustacea Ann Transvaal Mus 16 481-492

mdash mdash 1950 Descriptive catalogue of South African decapod Crustacea (crabs and shrimps) AnnSouth African Mus 38 1-837

BOCK W J 1986 Species concepts speciation and macroevolution In K IWATSUKIP H RAVEN amp W J BOCK (eds) Modern aspects of species 31-57 (University of TokyoPress Tokyo)

BOTT R 1955 Die Suumlsswasserkrabben von Afrika (Crust Decap) und ihre StammesgeschichteAnn Mus R Congo Belge (C Zool) 1 (33) 209-352 pls 1-30

BRUTON M N 1980 An outline of the ecology of the Mgobezeleni lake system at Sodwana withemphasis on the mangrove community In M N BRUTON amp K H COOPER (eds) Studieson the ecology of Maputaland 408-426 (Rhodes University Grahamstown)

CUMBERLIDGE N 1986 Ventilation of the branchial chambers in the amphibious West Africanfreshwater crab Sudanonautes (Convexonautes) aubryi monodi (Balss 1929) (BrachyuraPotamonautidae)Hydrobiol 134 53-65

mdash mdash 1991 The respiratory system of Globonautes macropus (Rathbun 1898) a terrestrialfreshwater crab from Liberia (GecarcinucoideaGecarcinucidae)Crustaceana 61 (1) 69-80

DANIELS S R B A STEWART amp M J GIBBONS 1998a Potamonautes granularis sp nov(Brachyura Potamonautidae) a new cryptic species of river crab from the Olifants Riversystem South Africa Crustaceana 71 (8) 885-903

mdash mdash mdash mdash amp mdash mdash 1998b Genetic and morphometric variation in the potamonautid river crabPotamonautes parvispina (Decapoda Potamonautidae) from two Western Cape rivers SouthAfrica Journ nat Hist London 32 1245-1258

mdash mdash mdash mdash amp mdash mdash 1999 Genetic structure among populations of Potamonautes perlatus(Decapoda Potamonautidae) from the Olifants River system in the Western Cape SouthAfrica Journ Zool London 249 (2) 137-142

DIacuteAZ H amp G RODRIacuteGUEZ 1977 The branchial chamber in terrestrial crabs a comparative studyBiol Bull Woods Hole 153 485-504

GOUWS G B A STEWART amp M COKE 2000 Evidence for a new species of river crab(Decapoda Brachyura Potamonautidae) from the Drakensberg South Africa Journ CrustBiol 20 (4) 743-758

GREENAWAY P amp H H TAYLOR 1976 Aerial gas exchange in Australian arid-zone crabParathelphusa transversa Von Martens Nature London 262 711-713

HILGENDORF F 1898 Die Land- und Suumlsswasser-Dekapoden Ostafrikas Die Thierwelt DeutschOst-Afrikas 4 (7) 1-37

LENZ H 1912 Afrikanische Crustaceen aus schwedischen Sammlungen Ark Zool 7 (29) 1-10MARKERT C L amp I FAULHABER 1965 Lactate dehydrogenase isozyme patterns of sh Journ

exp Zool 159 319-332MAYR E 1963 Animal species and evolution i-xiv 1-797 (Harvard University Press Cambridge

Massachusetts)mdash mdash 1970 Populations species and evolution i-xv 1-453 (Harvard University Press Cambridge

Massachusetts)

144 G GOUWS B A STEWART amp P E REAVELL

TABLE II(Continued)

Population

Locus Zululand A Mdibi Mapelane Zululand B Dakaneni Manzibomvu

GLN 41 26 25 13 25 1390 1000 0962 1000 1000 1000 100075 0000 0038 0000 0000 0000 0000

PGM-2N 56 26 25 13 25 13100 1000 1000 1000 0000 0040 000075 0000 0000 0000 1000 0960 1000

PHPN 41 26 25 13 25 13105 1000 0808 1000 1000 1000 100090 0000 0192 0000 0000 0000 0000

LGG-2N 41 26 25 13 24 13100 0854 0942 1000 0846 0979 069290 0146 0058 0000 0154 0021 0308

Genetic variability was low in all populations The percentage polymorphicloci (no criterion) ranged from 95 to 333 in the Mapelane and Dakanenipopulations respectively The mean unbiased expected heterozygosity varied from0034 (in the University of Zululand B population) to 0063 (in the Universityof Zululand A and Manzibomvu populations) The mean number of alleles perlocus ranged from 11 (in the Mapelane population) to 14 (in the Dakaneni andUniversity of Zululand A populations)

The dendrogram constructed based on the genetic identity values obtained bypairwise comparison of populations (table III) clearly distinguished two clusters( g 2) The group representing the form A populations clearly separated from thegroup representing the form B (Potamonautes sidneyi) populations at a geneticidentity value of I D 0829 D D 0187 Three loci contributed signi cantly tothis separation one of them diagnostically The HEX locus showed a xed alleledifference between the individuals of the two forms with the form A individualsbeing xed for the allele HEX100 and the form B (P sidneyi) individuals xed forthe HEX95 allele Strong heterogeneity was observed between the populations ofthe two forms at the IDH-1 and PGM-2 loci With the exception of one individualin the Dakaneni population having a homozygote with the PGM-2100 allele form Aand form B were characterized by the xation of alleles PGM-2100 and PGM-275

POTAMONAUTES LIVIDUS NOV 145

TABLE IIICoef cient matrix of Neirsquos (1978) unbiased genetic identity (above diagonal) and unbiased geneticdistance (below diagonal) for pairwise comparisons of the six populations of Potamonautes studied

Population

Zululand A Mdibi Mapelane Zululand B Dakaneni Manzibomvu

Zululand A currencurrencurrencurrencurren 0958 0949 0840 0855 0842

Mdibi 0043 currencurrencurrencurrencurren 0986 0821 0832 0822

Mapelane 0052 0014 currencurrencurrencurrencurren 0813 0825 0814

Zululand B 0174 0197 0206 currencurrencurrencurrencurren 0998 0999

Dakaneni 0157 0184 0193 0002 currencurrencurrencurrencurren 0994

Manzibomvu 0172 0196 0206 0001 0006 currencurrencurrencurrencurren

Fig 2 UPGMA dendrogram constructed from the matrix of Neirsquos (1978) unbiased genetic identi-ties (I ) using allozyme data from 21 loci

respectively Identity-values for within form comparisons varied from 0949 to0986 (D D 0014 to 0052) and 0994 to 0999 (D D 0001 to 0006) for form Aand form B respectively

Morphometric analysis mdash Individuals from the form A populations couldeasily be distinguished from the form B (P sidneyi) individuals by the possessionof a much more vaulted carapace in ated chelipeds a postfrontal crest whichdiminishes medially and the characteristic silver-blue carapace sheen and brightorange to red chelipeds and pereopods Mature form B (P sidneyi) individualsfrequently attained a larger size class (with CL being representative of size) thandid the mature form A individuals

146 G GOUWS B A STEWART amp P E REAVELL

Three carapace variables (ED CH and CWP) contributed signi cantly to thediscrimination between the two forms in the discriminant function analysis Thehistogram plot of observed canonical variable scores ( g 3) clearly separates thetwo forms with the canonical variable means of the form A and form B individualscalculated at iexcl0996 and 1965 respectively The classi cation function (the linearfunction of variables which best discriminates the individuals of one group fromthe other speci ed groupings) was calculated for individuals of each form Theclassi cation function of the form A group was

Y D 306704 (Log CWP) iexcl 26103 (Log ED) iexcl 228513 (Log CH) iexcl 64156

and of the form B (P sidneyi) group

Y D 35097 (Log ED) iexcl 315543 (Log CH) C 347231 (Log CWP) iexcl 88367

Using the classi cation functions individuals were reassigned to groups basedon highest a posteriori probabilities Of the form A individuals 9437 (134of 142) were correctly classi ed with eight individuals being reassigned to theform B group Of the form B individuals 8889 were correctly reassigned to theP sidneyi group with eight of the 72 individuals being reassigned to the form Agroup

Fig 3 Histogram of scores for specimens of Potamonautes lividus sp nov (form A) and P sidneyiRathbun 1904 (form B) along the canonical variable calculated from a discriminant function

analysis using seven carapace variables

POTAMONAUTES LIVIDUS NOV 147

Comparison of regressions of the most discriminating variables between the twoforms regressed over CL in turn also showed signi cant differences between thetwo forms CH regressed over CL showed highly signi cant differences betweenthe two forms (SS D 0011 df D 1 F D 31266 P lt 0001) as did ED(SS D 0011 df D 1 F D 8333 P lt 0005) and CWP (SS D 0006 df D 1F D 8136 P lt 0005) These represent the most discriminating variables andtheir regressions are represented graphically ( g 4a b c) PFCD (SS D 0199df D 1 F D 52671 P lt 0001) CWW (SS D 0003 df D 1 F D 30963P lt 0001) and CWA (SS D 0001 df D 1 F D 6182 P lt 002) also showedthat there were signi cant differences between the two forms but the discriminantfunction analysis showed them to be redundant in constructing the model

Qualitative analysis mdash Examination of gonopods and mouthparts revealed onlyslight differences in gonopod morphology The terminal segment of gonopod 1of the undescribed form was relatively short and triangular whereas the terminalsegment of gonopod 1 of P sidneyi appears to be substantially longer and moreslender Although the terminal segment is bent away from the medial line in bothforms the terminal segment in P sidneyi possesses a lobe or ange that extendsinwards giving the terminal segment an S-shaped appearance The gonopods andmandibular palps of the two forms are illustrated in g 5

DISCUSSION

The data presented above clearly indicate that the two forms of freshwatercrabs from KwaZulu-Natal are distinct The form A specimens are smaller with amore vaulted carapace that is relatively narrower posteriorly and that possessesa relatively narrower frontal lobe (ED) than that of the Potamonautes sidneyiindividuals

Not only are the two forms clearly distinct both biochemically and morpho-logically but strong evidence suggests that they are reproductively isolated Thepresence of a diagnostic locus HEX xed for alternate alleles in the sympatricpopulation of the two forms indicates that a lack of gene ow and thus repro-ductive isolation exist between the two forms This allows for species recognitionunder the Biological Species Concept (Mayr 1970) under which species are de- ned as ldquogroups of actually or potentially interbreeding populations which arereproductively isolated from other such groupsrdquo (Mayr 1963 19) or ldquogeneticallyisolated (in nature) from other such groupsrdquo (Bock 1986 33) In his model of al-lopatric speciation Bock (1986) suggested that newly evolved species in sympatrywould exert mutually selective demands on each other by means of reproductive

148 G GOUWS B A STEWART amp P E REAVELL

Fig 4 Comparisons of the regressions of (A) Log CH (carapace height) over Log CL (carapacelength) (B) Log ED (eye distance) over Log CL and (C) Log CWP (posterior carapace width) overLog CL between form A (Potamonautes lividus sp nov) and form B (P sidneyi Rathbun 1904) All

differences are signi cant (at the P lt 0005 level)

POTAMONAUTES LIVIDUS NOV 149

Fig 5 A-E form A (Potamonautes lividus sp nov composite of male holotype SAM A43540and unaccessioned material) A carapace outline B left mandibular palp anterior view C leftmandibular palp posterior view D left gonopod 1 anterior view and E left gonopod 1 posteriorview F-J form B (Potamonautes sidneyi Rathbun 1904 unaccessioned specimen) F carapaceoutline G left mandibular palp anterior view H left mandibular palp posterior view I left

gonopod 1 anterior view J left gonopod 1 posterior view

150 G GOUWS B A STEWART amp P E REAVELL

interference and ecological competition This would lead to a divergence of mor-phological and behavioural aspects of feeding reproduction and other ecologicalfeatures The different gonopod morphologies of the two forms may re ect this

The three form A populations clustered separately from the three P sidneyipopulations at a I -value of 0829 Stewart (1997a) calculated the separationI -value between P parvispina Stewart 1997 and P perlatus H Milne Edwards1837 to be 068 An I -value of 066 separated both P perlatus and P brinckiBott 1960 in the Western Cape (Stewart 1997b) and P unispinus Stewart ampCook 1998 and P sidneyi in Mpumalanga (Stewart amp Cook 1998) An I -valueof 0599 was obtained separating P clarus Gouws Stewart amp Coke 2000 andP depressus (Gouws et al 2000) The only species in the genus delineated using ahigher I -value was P granularis Daniels Stewart amp Gibbons 1998 which wasseparated from P perlatus in the Olifants River at a I -value of 088 (Danielset al 1998a 1999) Although slightly higher than most interspeci c values inthe genus the value obtained in this study nevertheless falls within the range (035to 085) speci ed by Thorpe (1982) to indicate congeneric species differencesAllopatric populations showing I -values of less than 085 are unlikely to beconspeci c (Thorpe amp Soleacute-Cava 1994) With the exception of two cases allpairwise comparisons between allopatric populations of the two forms yieldedI -values less than 085

Identity-values were high for comparisons within both the form A (0949 to0986) and P sidneyi (0994 to 0999) groups Intraspeci c I -values are generallyhigh in the genus Potamonautes and disjunct populations within a species tendto be genetically undifferentiated Intraspeci c I -values obtained in six studies(Stewart 1997a b Stewart amp Cook 1998 Daniels et al 1998b 1999) involvingsix Potamonautes species varied from 0902 to 1000 (D D 0000 to 0103)An intraspeci c I -value of 075 was obtained in a comparison of two groups ofP brincki populations across the Cape Peninsula and Cape Flats However thismost probably indicates a species difference and requires further investigation(Stewart 1997b) Given the high intraspeci c I -values characteristic of the genusand those obtained for comparisons within each form the I -value obtainedfor the comparison between the two forms most likely represents a speciesdifference

Bock (1986) also de ned a species as possessing a set of three distinctcharacteristics genetic unity reproductive unity and ecological unity Biochemicaldata provide support for compliance with the rst two criteria for both formsWhile no empirical evidence is as yet available con rming the third factor adegree of macro- and microhabitat segregation and thus ecological segregationis evident between the two forms Potamonautes sidneyi is widespread acrossthe province (Stewart et al 1995) while the other form appears to have a

POTAMONAUTES LIVIDUS NOV 151

more limited distribution in northeastern KwaZulu-Natal restricted to patches ofswamp forest with particular oral assemblages The swamp forests are oftencharacterized by Barringtonia racemosa Syzygium cordatum Ficus trichopodaHibiscus tiliaceus L Rauvola caffra Sond Voacanga thouarsii Roem amp SchultRaphia australis Oberm amp Strey and Podocarpus falcatus (Thunb) R Br exMirb with the fern Stenochlaena tenuifolia (Desv) T Moore often present in theunderstorey (Bruton 1980 Moll 1980) Within the swamp forests the sympatricpopulations appear to show a degree of microhabitat segregation Observationssuggest that P sidneyi has a closer association with water as individuals were nevercollected great distances away from seepage pools and channels owing throughthe forest Conversely individuals of the swamp-forest form were most oftencollected farther from water and their burrows were often among the vegetationObservations suggest that this form is more terrestrial Individuals were noticedto move to higher elevations when the water table rose through the hydromorphicpeat soil ooding their burrows and the surface and they were also more active oncloudy overcast days Evidence of terrestrial adaptation is most likely to be foundin the structure and histology of the organs and tissues involved in respirationfactors such as branchial chamber shape and volume gill structure and formulaand the structure and vascularization of the branchiostegite lining are knownto re ect changes brought upon by the constraints of the terrestrial environment(Greenaway amp Taylor 1976 Diacuteaz amp Rodriacuteguez 1977 Taylor amp Greenaway1979 Cumberlidge 1986 1991 Takeda et al 1996) Although the availabilityof material prohibited the investigation of this aspect future research may prove tobe fruitful and highlight a greater distinction between the two forms

Studies on terrestrial adaptation supplemented by behavioural data that couldillustrate microhabitat and ecological segregation would quantify further thedegree of differentiation between the two forms However two independent datasets biochemical and morphological present strong evidence for the speci c statusof the swamp-forest form

TAXONOMY

Potamonautes lividus sp nov ( gs 6-7)

Material examined mdash Holotype South African Museum (SAM) A43540 one male CL D255 mm Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws andL Hoenson Allotype SAM A43541 one female CL D 245 mm Ficus and Barringtonia swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S 32plusmn2401800E)coll 27 January 1997 by B A Stewart G Gouws and L Hoenson Other material SAM A43542two males Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws

152 G GOUWS B A STEWART amp P E REAVELL

and L Hoenson SAM A43543 one female Lake Nhlabane north of Richards Bay (28plusmn3800500S32plusmn1601700E) coll 27 April 1993 by the University of Zululand Zoology Department SAMA43544 three males one female Mdibi swamp forest along Mdibi stream 8 km north of RichardsBay (28plusmn4202400S 32plusmn0902600E) coll 26 January 1997 by B A Stewart P A Cook M CokeP E Reavell G Gouws and L Hoenson SAM A43545 one male one female Syzygium forestUniversity of Zululand campus (28plusmn5102500S 31plusmn5100200E) coll 24 January 1997 by B A StewartP A Cook P E Reavell G Gouws and L Hoenson SAM A43546 two males two femalesUniversity of Zululand stream owing through campus (28plusmn550S 31plusmn410E) coll 10 September 1995by P E Reavell SAM A41313 one male one female swamp forest Empangeni (28plusmn5102500S31plusmn5100200E) coll 2 August 1994 by M Coke SAM A41155 one male University of ZululandSyzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S 31plusmn450E) coll 10 December1988 by P E Reavell SAM A41153 three males smaller holes in hydromorphic soil Syzygiumcordatum swamp forest University of Zululand (28plusmn450S 31plusmn450E) coll 20 March 1994 byP E Reavell SAM A41156 one female Syzygium cordatum swamp forest University of Zululand(28plusmn450S 31plusmn450E) coll 18 May 1992 by P E Reavell SAM A41154 one male one femaleUniversity of Zululand Syzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S31plusmn450E) coll 10 May 1990 by P E Reavell SAM A43547 two males one female swamp forestUniversity of Zululand (28plusmn450S 31plusmn450E) coll 1 April 1994 by P E Reavell SAM A43548one male one female Syzygium and Bridelia dominated swamp forest University of Zululand(28plusmn5102500S 31plusmn5100200E) coll 7 October 1996 by P E Reavell SAM A43549 one female Mdibiswamp forest Lake Msingazi catchment area north of Richards Bay (28plusmn420S 32plusmn090E) coll5 December 1996 by P E Reavell Albany Museum mdash GEN910 one female Mpolozi swampsMapelane (28plusmn2601300S 32plusmn2402500E) coll 13 February 1991 Albany Museum mdash GEN965 twomales ve females NrsquoKoninga Valley Richards Bay (28plusmn450S 32plusmn030E) coll 7 April 1988

Other material mdash The following specimens included in the collections of the South AfricanMuseum warrant further investigation as although they bear some resemblance to the speciesdescribed below their identi cation is uncertain SAM A41276 one male one female Mbonenidam Mkuze Game Reserve (27plusmn3705700S 32plusmn1504500E) coll 28 October 1994 by M Coke SAMA41299 two males Nxwala stream Mkuze Game Reserve (27plusmn4302300S 32plusmn1601000E) coll 10November 1994 by O Bourquin SAM A41277 one male Rainpool south of entrance False BayPark (28plusmn0000100S 32plusmn2102100E) coll 26 October 1994 by M Coke SAM A41300 two malesKangela rainpoolN2 near Mtubatuba (28plusmn2200000S 32plusmn1103600E) coll 25 October 1994 by M Cokeand SAM A41211 one male Ntambanana (Ntrabanana) Zululand coll by H H Curson

Type locality mdash South Africa KwaZulu-Natal Barringtonia and Ficus swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S32plusmn2401800E)

Distribution mdash At present known only from the swamp forests (characterizedby Barringtonia racemosa Syzygium cordatum and Ficus trichopoda vegetationand spongy hydromorphic peat-soil) in the vicinity of Richards Bay Empangeniand the Mapelane Nature Reserve It is probable that the distribution of the speciesmay extend into low-lying areas to the east of the Drakensberg escarpment in theprovince of Mpumalanga and into Mozambique

Etymology mdash From the Latin ldquolividusrdquo meaning ldquobluerdquo or ldquolight bluerdquoreferring to the characteristic silver-blue sheen of the carapace The epitheton isan adjective agreeing in gender with the (masculine) generic name

POTAMONAUTES LIVIDUS NOV 153

Fig 6 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A wholeanimal dorsal aspect B whole animal ventral aspect C cephalothorax frontal aspect

Diagnosis mdash Carapace distinctly vaulted and relatively narrow posteriorlyEpibranchial teeth absent and anterolateral margin of the carapace smooth Post-frontal crest indistinct medially with frontal lobe projecting downwards Cara-pace characteristically orange to red with silver-blue sheen Chelipeds and limbs

154 G GOUWS B A STEWART amp P E REAVELL

bright orange to red with lighter cheliped and dactyl tips Chela in ated and highlyarched

Description of male holotype mdash Size Measurements of the holotype and theranges of other specimens are given in table IV

Carapace ( gs 6A C 7A) Carapace and limbs characteristically orange tored with the carapace possessing a silver-blue sheen when alive Preserved spec-imens (70 ethanol) appear less orange and the carapace retains a blue-greycolour Cephalothorax ovoid distinctly vaulted branchial region highly convex( g 6A C) maximum height and width at anterior third (ratio CHCL D 065CWWCL D 145) Anterior margin straight Urogastric grooves moderately wellde ned Cardiac grooves shallow and poorly de ned Carapace otherwise smoothPostfrontal crest smooth curves forward medially Postfrontal crest diminishesabove inner orbit margins though well de ned immediately lateral to forked mid-point groove by means of two indentations anterior to crest indicating epigas-tric lobes Exorbital teeth moderately sharp but small Epibranchial teeth ab-sent Anterolateral margin posterior to postfrontal crest smooth margin curvingin over carapace in branchial region though indistinctly Each ank has a longitu-dinal groove dividing the subhepatic from the pterygostomial region with verticalgroove running from longitudinal groove joining anterolateral margin between ex-orbital tooth and postfrontal crest

Sternites ( gs 6B 7B) Sternites 1 and 2 fused no suture visible First suture(sternal groove) between sternites 2 and 3 complete Second sternal groove

TABLE IVPotamonautes lividus sp nov wet weight (in g) and measurements (in mm) for the male holotype

and ranges for other individuals examined (maximum of 77 males and 70 females)

Variable Abbreviation Holotype Males Females

Wet weight WW 242 05-214 07-183Carapace length CL 255 84-247 89-276Carapace widest width CWW 370 114-360 118-373Carapace posterior width CWP 281 90-269 86-306Distance between postfrontal crest

and anterior margin PFCD 43 12-222 15-46Distance between orbits ED 114 42-119 43-123Distance between exorbital teeth CWA 259 96-254 96-262Carapace height CH 165 48-171 50-162Width of sixth abdominal segment AW6 75 28-74 31-240Major cheliped propodus length MCPL 427 71-402 76-291Major cheliped propodus height MCPH 198 28-189 28-142Pereopod 2 merus length P2ML 189 50-181 51-171Pereopod 2 merus width P2MW 58 19-56 18-59

POTAMONAUTES LIVIDUS NOV 155

Fig 7 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A carapaceoutline B thoracic sternum C right cheliped dactylus and propodus D left cheliped dactylusand propodus E left third maxilliped F left mandible and mandibular palp posterior view G leftmandibular palp posterior view H left mandibular palp anterior view I left gonopod 1 anteriorview J terminal segment left gonopod 1 anterior view K left gonopod 1 posterior view L leftgonopod 2 anterior view Scale lines represent 1 mm except for A-D where they represent 10 mm

156 G GOUWS B A STEWART amp P E REAVELL

between sternites 3 and 4 complete laterally becoming shallower mediallysloping sharply towards abdominopelvic region

Third maxillipeds ( gs 6C 7E) Filling entire buccal frame except for ovalefferent respiratory openings short agellum present on exopods ischium smoothwith moderately deep vertical groove

Mandibular palp ( g 7F G H) Mandibular palp with two segments terminalsegment undivided with a dense tuft of setae on posterior surface of angeof terminal segment Margins generally hirsute Subterminal segment slightlyenlarged distally

Chelipeds and walking legs ( gs 6A 7C D) Chelipeds markedly unequaldactylus of right cheliped strongly arched 163 times length of dactylus of leftcheliped Both dactyli armed with up to 20 cutting teeth three to four of whichare slightly larger and more prominent Propodus of right cheliped markedlyin ated 168 times longer and 20 times wider than that of left cheliped Pollexpossesses 20 cutting teeth four to ve of which are more prominent Carpi ofboth chelipeds possess one prominent and three rudimentary teeth Margins ofmeri granulose small blunt spine on anterior surface no spine on anterior-inferiormargin Pereopods generally slender (pereopod 2 merus length width D 328 andpereopod 5 merus lengthwidth D 271) P3 longest P5 shortest ventral marginsof propodi and meri smooth dorsal margin with ne sharp bristles dactyli endingin sharp points with margins bearing a series of sharp spinelike bristles

Pleon ( gs 6B 7B) First ve segments broad and short last two segmentslonger terminal segment rounded at distal end

Pleopods ( g 7I J K) Pleopod 1 (gonopod 1) terminal segment short 025times length of subterminal segment terminal segment curves away from mid-line when viewed posteriorly widest at base ending in pointed tip Subterminalsegment of pleopod 1 tapers distally inner lateral margin slightly irregular outerlateral margin straighter both margins hirsute Posterior surface with twisting lon-gitudinal groove extending length of subterminal and terminal segment Groovenot visible on anterior surface Posterior surface and margins of groove hirsutePleopod 2 (gonopod 2) terminal segment lament-like 05 the length of subter-minal segment curving slightly towards medial line proximally curves away frommedial line distally ( g 7L) Subterminal segment widest at base tapering sharplyinwards at 04 of length forms narrow process supporting terminal segment

Variation mdash All individuals are characteristically dark orange to red witha silver-blue sheen to the carapace while the chelipeds vary in colour frombright orange-red to a lighter yellow-orange All individuals are characterized byhighly vaulted carapaces and downwardly projecting frontal lobes The postfrontalcrest which is most pronounced laterally (from directly above the orbits to theanterolateral margin) and incomplete medially is often more distinct in the smaller

POTAMONAUTES LIVIDUS NOV 157

individuals Chelipeds are not always typically arched enclosing a large ovoidspace as in the holotype Chelipeds of smaller individuals although in ated areless arched and often tight closing with the small cutting teeth more obviousChelipeds of females and small males in particular from the Mdibi and Universityof Zululand localities have propodi that are relatively high with in ated palmsand relatively short tightly closing chelae which project slightly downwardsHeterochely has been demonstrated in most Potamonautes-species occurring inSouth Africa (Siegfried 1972 Raubenheimer 1986 Stewart et al 1995 Stewart1997a b Stewart amp Cook 1998 Daniels et al 1998a Gouws et al 2000) Withinthe species 76 of the specimens were right-handed with 11 being left-handedand 13 being of equal or subequal (differing by less than one millimeter) sizeOf the males 79 were right-handed 8 left-handed and 13 equal or subequalFemales had 74 right-handedness 13 left-handedness and in 13 of caseschelipeds were equal or subequal The abdomen of mature females completelyoverlaps the coxae of the pereopods The smallest mature female had a CL of167 mm with the largest immature female having a CL of 159 indicating that thepubertal moult occurs approximately between the 14 mm and 18 mm size classes

Remarks mdash Potamonautes lividus sp nov can readily be distinguished from theten other species in the genus Potamonautes known to occur within South AfricaPotamonautes warreni Calman 1918 P dentatus P parvispina and P unispinusall bear a singular spine or a series of teeth on the anterolateral margins whereasP lividus sp nov is smooth Potamonautes perlatus P sidneyi and P granularisare all larger crabs with in ated arched carapaces with complete distinct post-frontal crests and scabrosity or granulation of the anterior margins orbits epi-branchial corners or postfrontal crests Potamonautes lividus sp nov has smoothcarapace margins and a incomplete postfrontal crest The terminal segment ofgonopod 1 in P lividus sp nov is relatively short and triangular and curves awayfrom the medial line when viewed posteriorly while that of P sidneyi is relativelylonger more slender and more S-shaped The postfrontal crest of P sidneyi mayjoin the anterolateral margin at a relatively sharp angle and form a pronouncedepibranchial corner along the anterolateral margin The anterolateral margin inP lividus sp nov is more rounded and the epibranchial corners slope down to-wards the anks Potamonautes granularis is chocolate brown with orange tips tothe chelipeds Potamonautes brincki is a smaller crab with a smoother carapacethough also chocolate to reddish-brown in colour with a nely granulated antero-lateral margin which does not curve in over the carapace in the branchial region(Stewart 1997b) Potamonautes depressus and P clarus both have rounded epi-branchial corners and smooth carapaces though these are relatively shallow andhave attened dorsal surfaces Both are characterized by long slender limbs Pota-monautes depressus is brown to green-brown in colour while P clarus is brightorange in colour

158 G GOUWS B A STEWART amp P E REAVELL

A number of species from further a eld bear a super cial resemblance toP lividus sp nov particularly with regard to carapace morphology though in mostcases they can be readily distinguished Potamonautes pilosus Hilgendorf 1898 isknown from East Africa and is a small crab with a CWW of less than 25 mmSpecimens possess a weak postfrontal crest which along with the anterolateralmargin can be granulated (Hilgendorf 1898 Bott 1955) Potamonautes neumanniHilgendorf 1898 is known from East Africa and has a characteristically vaultedcarapace without a complete distinct postfrontal crest (Hilgendorf 1898 Bott1955) The postfrontal crest is more distinct in P lividus particularly laterally andthe exorbital teeth are sharper and more de ned in P lividus than in P neumanniThe terminal segment of gonopod 1 is longer and more slender in P neumannithan in P lividus and curves distinctly outwards The subterminal segment ofgonopod 1 is wider at its apex in P neumanni than in P lividus Additionally thecarapace of preserved specimens of P neumanni is typically grey in colour whileliving specimens are violet in colour with bright olive-green limbs and chelipeds(Hilgendorf 1898) Potamonautes ballayi acristatus Bott 1955 has an incompletepostfrontal crest only present above the orbits and small and blunt exorbital teethThe major chela although highly arched and the minor chela are long and moreslender than those of P lividus sp nov The terminal segment of gonopod 1 ofP granviki Colosi 1924 is curved towards the medial line when viewed posteriorly(Bott 1955) The chelae of both P berardi berardi Audouin 1826 and P b ignestiiParisi 1923 are relatively short and high with stout downward-projecting ngersThe anterior margin of the frontal lobe of P b berardi shows a distinct invaginationand the anterolateral margin appears sharp and less rounded than in P lividus spnov while the postfrontal crest of P b ignestii is complete and has a fairly longmedial groove Potamonautes emini emini Hilgendorf 1892 are generally smallcrabs with a less in ated carapace and short stout chelipeds The subterminaland terminal segments of gonopod 1 are of more or less equal size (Bott 1955)Potamonautes e semilunaris Bott 1955 and P luashiensis Bott 1955 are alsosmall crabs (CWW lt 20 mm) with the postfrontal crest only visible laterally andin the case of P luashiensis the anterolateral margin and postfrontal crest mayshow granulation Potamonautes didieri Rathbun 1904 possesses a more completerounded postfrontal crest and shorter more stout chelipeds (Bott 1955)

ACKNOWLEDGEMENTS

Financial assistance was kindly provided by the World Wildlife Fund - SouthAfrica the Foundation for Research Development and the University of ZululandThe KwaZulu-Natal Nature Conservation Services provided accommodation and

POTAMONAUTES LIVIDUS NOV 159

logistic support Liz Hoenson Peter Cook Mike Coke and Tyrone Ridgway arethanked for assistance in the eld and Michelle van der Merwe is thanked foraiding in the photography and drafting of gures The authors wish to thank ananonymous reviewer for comments on the manuscript

REFERENCES

BARNARD K H 1935 Scienti c results of the Vernay-Lang Kalahari expedition March toSeptember 1930 Crustacea Ann Transvaal Mus 16 481-492

mdash mdash 1950 Descriptive catalogue of South African decapod Crustacea (crabs and shrimps) AnnSouth African Mus 38 1-837

BOCK W J 1986 Species concepts speciation and macroevolution In K IWATSUKIP H RAVEN amp W J BOCK (eds) Modern aspects of species 31-57 (University of TokyoPress Tokyo)

BOTT R 1955 Die Suumlsswasserkrabben von Afrika (Crust Decap) und ihre StammesgeschichteAnn Mus R Congo Belge (C Zool) 1 (33) 209-352 pls 1-30

BRUTON M N 1980 An outline of the ecology of the Mgobezeleni lake system at Sodwana withemphasis on the mangrove community In M N BRUTON amp K H COOPER (eds) Studieson the ecology of Maputaland 408-426 (Rhodes University Grahamstown)

CUMBERLIDGE N 1986 Ventilation of the branchial chambers in the amphibious West Africanfreshwater crab Sudanonautes (Convexonautes) aubryi monodi (Balss 1929) (BrachyuraPotamonautidae)Hydrobiol 134 53-65

mdash mdash 1991 The respiratory system of Globonautes macropus (Rathbun 1898) a terrestrialfreshwater crab from Liberia (GecarcinucoideaGecarcinucidae)Crustaceana 61 (1) 69-80

DANIELS S R B A STEWART amp M J GIBBONS 1998a Potamonautes granularis sp nov(Brachyura Potamonautidae) a new cryptic species of river crab from the Olifants Riversystem South Africa Crustaceana 71 (8) 885-903

mdash mdash mdash mdash amp mdash mdash 1998b Genetic and morphometric variation in the potamonautid river crabPotamonautes parvispina (Decapoda Potamonautidae) from two Western Cape rivers SouthAfrica Journ nat Hist London 32 1245-1258

mdash mdash mdash mdash amp mdash mdash 1999 Genetic structure among populations of Potamonautes perlatus(Decapoda Potamonautidae) from the Olifants River system in the Western Cape SouthAfrica Journ Zool London 249 (2) 137-142

DIacuteAZ H amp G RODRIacuteGUEZ 1977 The branchial chamber in terrestrial crabs a comparative studyBiol Bull Woods Hole 153 485-504

GOUWS G B A STEWART amp M COKE 2000 Evidence for a new species of river crab(Decapoda Brachyura Potamonautidae) from the Drakensberg South Africa Journ CrustBiol 20 (4) 743-758

GREENAWAY P amp H H TAYLOR 1976 Aerial gas exchange in Australian arid-zone crabParathelphusa transversa Von Martens Nature London 262 711-713

HILGENDORF F 1898 Die Land- und Suumlsswasser-Dekapoden Ostafrikas Die Thierwelt DeutschOst-Afrikas 4 (7) 1-37

LENZ H 1912 Afrikanische Crustaceen aus schwedischen Sammlungen Ark Zool 7 (29) 1-10MARKERT C L amp I FAULHABER 1965 Lactate dehydrogenase isozyme patterns of sh Journ

exp Zool 159 319-332MAYR E 1963 Animal species and evolution i-xiv 1-797 (Harvard University Press Cambridge

Massachusetts)mdash mdash 1970 Populations species and evolution i-xv 1-453 (Harvard University Press Cambridge

Massachusetts)

POTAMONAUTES LIVIDUS NOV 145

TABLE IIICoef cient matrix of Neirsquos (1978) unbiased genetic identity (above diagonal) and unbiased geneticdistance (below diagonal) for pairwise comparisons of the six populations of Potamonautes studied

Population

Zululand A Mdibi Mapelane Zululand B Dakaneni Manzibomvu

Zululand A currencurrencurrencurrencurren 0958 0949 0840 0855 0842

Mdibi 0043 currencurrencurrencurrencurren 0986 0821 0832 0822

Mapelane 0052 0014 currencurrencurrencurrencurren 0813 0825 0814

Zululand B 0174 0197 0206 currencurrencurrencurrencurren 0998 0999

Dakaneni 0157 0184 0193 0002 currencurrencurrencurrencurren 0994

Manzibomvu 0172 0196 0206 0001 0006 currencurrencurrencurrencurren

Fig 2 UPGMA dendrogram constructed from the matrix of Neirsquos (1978) unbiased genetic identi-ties (I ) using allozyme data from 21 loci

respectively Identity-values for within form comparisons varied from 0949 to0986 (D D 0014 to 0052) and 0994 to 0999 (D D 0001 to 0006) for form Aand form B respectively

Morphometric analysis mdash Individuals from the form A populations couldeasily be distinguished from the form B (P sidneyi) individuals by the possessionof a much more vaulted carapace in ated chelipeds a postfrontal crest whichdiminishes medially and the characteristic silver-blue carapace sheen and brightorange to red chelipeds and pereopods Mature form B (P sidneyi) individualsfrequently attained a larger size class (with CL being representative of size) thandid the mature form A individuals

146 G GOUWS B A STEWART amp P E REAVELL

Three carapace variables (ED CH and CWP) contributed signi cantly to thediscrimination between the two forms in the discriminant function analysis Thehistogram plot of observed canonical variable scores ( g 3) clearly separates thetwo forms with the canonical variable means of the form A and form B individualscalculated at iexcl0996 and 1965 respectively The classi cation function (the linearfunction of variables which best discriminates the individuals of one group fromthe other speci ed groupings) was calculated for individuals of each form Theclassi cation function of the form A group was

Y D 306704 (Log CWP) iexcl 26103 (Log ED) iexcl 228513 (Log CH) iexcl 64156

and of the form B (P sidneyi) group

Y D 35097 (Log ED) iexcl 315543 (Log CH) C 347231 (Log CWP) iexcl 88367

Using the classi cation functions individuals were reassigned to groups basedon highest a posteriori probabilities Of the form A individuals 9437 (134of 142) were correctly classi ed with eight individuals being reassigned to theform B group Of the form B individuals 8889 were correctly reassigned to theP sidneyi group with eight of the 72 individuals being reassigned to the form Agroup

Fig 3 Histogram of scores for specimens of Potamonautes lividus sp nov (form A) and P sidneyiRathbun 1904 (form B) along the canonical variable calculated from a discriminant function

analysis using seven carapace variables

POTAMONAUTES LIVIDUS NOV 147

Comparison of regressions of the most discriminating variables between the twoforms regressed over CL in turn also showed signi cant differences between thetwo forms CH regressed over CL showed highly signi cant differences betweenthe two forms (SS D 0011 df D 1 F D 31266 P lt 0001) as did ED(SS D 0011 df D 1 F D 8333 P lt 0005) and CWP (SS D 0006 df D 1F D 8136 P lt 0005) These represent the most discriminating variables andtheir regressions are represented graphically ( g 4a b c) PFCD (SS D 0199df D 1 F D 52671 P lt 0001) CWW (SS D 0003 df D 1 F D 30963P lt 0001) and CWA (SS D 0001 df D 1 F D 6182 P lt 002) also showedthat there were signi cant differences between the two forms but the discriminantfunction analysis showed them to be redundant in constructing the model

Qualitative analysis mdash Examination of gonopods and mouthparts revealed onlyslight differences in gonopod morphology The terminal segment of gonopod 1of the undescribed form was relatively short and triangular whereas the terminalsegment of gonopod 1 of P sidneyi appears to be substantially longer and moreslender Although the terminal segment is bent away from the medial line in bothforms the terminal segment in P sidneyi possesses a lobe or ange that extendsinwards giving the terminal segment an S-shaped appearance The gonopods andmandibular palps of the two forms are illustrated in g 5

DISCUSSION

The data presented above clearly indicate that the two forms of freshwatercrabs from KwaZulu-Natal are distinct The form A specimens are smaller with amore vaulted carapace that is relatively narrower posteriorly and that possessesa relatively narrower frontal lobe (ED) than that of the Potamonautes sidneyiindividuals

Not only are the two forms clearly distinct both biochemically and morpho-logically but strong evidence suggests that they are reproductively isolated Thepresence of a diagnostic locus HEX xed for alternate alleles in the sympatricpopulation of the two forms indicates that a lack of gene ow and thus repro-ductive isolation exist between the two forms This allows for species recognitionunder the Biological Species Concept (Mayr 1970) under which species are de- ned as ldquogroups of actually or potentially interbreeding populations which arereproductively isolated from other such groupsrdquo (Mayr 1963 19) or ldquogeneticallyisolated (in nature) from other such groupsrdquo (Bock 1986 33) In his model of al-lopatric speciation Bock (1986) suggested that newly evolved species in sympatrywould exert mutually selective demands on each other by means of reproductive

148 G GOUWS B A STEWART amp P E REAVELL

Fig 4 Comparisons of the regressions of (A) Log CH (carapace height) over Log CL (carapacelength) (B) Log ED (eye distance) over Log CL and (C) Log CWP (posterior carapace width) overLog CL between form A (Potamonautes lividus sp nov) and form B (P sidneyi Rathbun 1904) All

differences are signi cant (at the P lt 0005 level)

POTAMONAUTES LIVIDUS NOV 149

Fig 5 A-E form A (Potamonautes lividus sp nov composite of male holotype SAM A43540and unaccessioned material) A carapace outline B left mandibular palp anterior view C leftmandibular palp posterior view D left gonopod 1 anterior view and E left gonopod 1 posteriorview F-J form B (Potamonautes sidneyi Rathbun 1904 unaccessioned specimen) F carapaceoutline G left mandibular palp anterior view H left mandibular palp posterior view I left

gonopod 1 anterior view J left gonopod 1 posterior view

150 G GOUWS B A STEWART amp P E REAVELL

interference and ecological competition This would lead to a divergence of mor-phological and behavioural aspects of feeding reproduction and other ecologicalfeatures The different gonopod morphologies of the two forms may re ect this

The three form A populations clustered separately from the three P sidneyipopulations at a I -value of 0829 Stewart (1997a) calculated the separationI -value between P parvispina Stewart 1997 and P perlatus H Milne Edwards1837 to be 068 An I -value of 066 separated both P perlatus and P brinckiBott 1960 in the Western Cape (Stewart 1997b) and P unispinus Stewart ampCook 1998 and P sidneyi in Mpumalanga (Stewart amp Cook 1998) An I -valueof 0599 was obtained separating P clarus Gouws Stewart amp Coke 2000 andP depressus (Gouws et al 2000) The only species in the genus delineated using ahigher I -value was P granularis Daniels Stewart amp Gibbons 1998 which wasseparated from P perlatus in the Olifants River at a I -value of 088 (Danielset al 1998a 1999) Although slightly higher than most interspeci c values inthe genus the value obtained in this study nevertheless falls within the range (035to 085) speci ed by Thorpe (1982) to indicate congeneric species differencesAllopatric populations showing I -values of less than 085 are unlikely to beconspeci c (Thorpe amp Soleacute-Cava 1994) With the exception of two cases allpairwise comparisons between allopatric populations of the two forms yieldedI -values less than 085

Identity-values were high for comparisons within both the form A (0949 to0986) and P sidneyi (0994 to 0999) groups Intraspeci c I -values are generallyhigh in the genus Potamonautes and disjunct populations within a species tendto be genetically undifferentiated Intraspeci c I -values obtained in six studies(Stewart 1997a b Stewart amp Cook 1998 Daniels et al 1998b 1999) involvingsix Potamonautes species varied from 0902 to 1000 (D D 0000 to 0103)An intraspeci c I -value of 075 was obtained in a comparison of two groups ofP brincki populations across the Cape Peninsula and Cape Flats However thismost probably indicates a species difference and requires further investigation(Stewart 1997b) Given the high intraspeci c I -values characteristic of the genusand those obtained for comparisons within each form the I -value obtainedfor the comparison between the two forms most likely represents a speciesdifference

Bock (1986) also de ned a species as possessing a set of three distinctcharacteristics genetic unity reproductive unity and ecological unity Biochemicaldata provide support for compliance with the rst two criteria for both formsWhile no empirical evidence is as yet available con rming the third factor adegree of macro- and microhabitat segregation and thus ecological segregationis evident between the two forms Potamonautes sidneyi is widespread acrossthe province (Stewart et al 1995) while the other form appears to have a

POTAMONAUTES LIVIDUS NOV 151

more limited distribution in northeastern KwaZulu-Natal restricted to patches ofswamp forest with particular oral assemblages The swamp forests are oftencharacterized by Barringtonia racemosa Syzygium cordatum Ficus trichopodaHibiscus tiliaceus L Rauvola caffra Sond Voacanga thouarsii Roem amp SchultRaphia australis Oberm amp Strey and Podocarpus falcatus (Thunb) R Br exMirb with the fern Stenochlaena tenuifolia (Desv) T Moore often present in theunderstorey (Bruton 1980 Moll 1980) Within the swamp forests the sympatricpopulations appear to show a degree of microhabitat segregation Observationssuggest that P sidneyi has a closer association with water as individuals were nevercollected great distances away from seepage pools and channels owing throughthe forest Conversely individuals of the swamp-forest form were most oftencollected farther from water and their burrows were often among the vegetationObservations suggest that this form is more terrestrial Individuals were noticedto move to higher elevations when the water table rose through the hydromorphicpeat soil ooding their burrows and the surface and they were also more active oncloudy overcast days Evidence of terrestrial adaptation is most likely to be foundin the structure and histology of the organs and tissues involved in respirationfactors such as branchial chamber shape and volume gill structure and formulaand the structure and vascularization of the branchiostegite lining are knownto re ect changes brought upon by the constraints of the terrestrial environment(Greenaway amp Taylor 1976 Diacuteaz amp Rodriacuteguez 1977 Taylor amp Greenaway1979 Cumberlidge 1986 1991 Takeda et al 1996) Although the availabilityof material prohibited the investigation of this aspect future research may prove tobe fruitful and highlight a greater distinction between the two forms

Studies on terrestrial adaptation supplemented by behavioural data that couldillustrate microhabitat and ecological segregation would quantify further thedegree of differentiation between the two forms However two independent datasets biochemical and morphological present strong evidence for the speci c statusof the swamp-forest form

TAXONOMY

Potamonautes lividus sp nov ( gs 6-7)

Material examined mdash Holotype South African Museum (SAM) A43540 one male CL D255 mm Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws andL Hoenson Allotype SAM A43541 one female CL D 245 mm Ficus and Barringtonia swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S 32plusmn2401800E)coll 27 January 1997 by B A Stewart G Gouws and L Hoenson Other material SAM A43542two males Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws

152 G GOUWS B A STEWART amp P E REAVELL

and L Hoenson SAM A43543 one female Lake Nhlabane north of Richards Bay (28plusmn3800500S32plusmn1601700E) coll 27 April 1993 by the University of Zululand Zoology Department SAMA43544 three males one female Mdibi swamp forest along Mdibi stream 8 km north of RichardsBay (28plusmn4202400S 32plusmn0902600E) coll 26 January 1997 by B A Stewart P A Cook M CokeP E Reavell G Gouws and L Hoenson SAM A43545 one male one female Syzygium forestUniversity of Zululand campus (28plusmn5102500S 31plusmn5100200E) coll 24 January 1997 by B A StewartP A Cook P E Reavell G Gouws and L Hoenson SAM A43546 two males two femalesUniversity of Zululand stream owing through campus (28plusmn550S 31plusmn410E) coll 10 September 1995by P E Reavell SAM A41313 one male one female swamp forest Empangeni (28plusmn5102500S31plusmn5100200E) coll 2 August 1994 by M Coke SAM A41155 one male University of ZululandSyzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S 31plusmn450E) coll 10 December1988 by P E Reavell SAM A41153 three males smaller holes in hydromorphic soil Syzygiumcordatum swamp forest University of Zululand (28plusmn450S 31plusmn450E) coll 20 March 1994 byP E Reavell SAM A41156 one female Syzygium cordatum swamp forest University of Zululand(28plusmn450S 31plusmn450E) coll 18 May 1992 by P E Reavell SAM A41154 one male one femaleUniversity of Zululand Syzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S31plusmn450E) coll 10 May 1990 by P E Reavell SAM A43547 two males one female swamp forestUniversity of Zululand (28plusmn450S 31plusmn450E) coll 1 April 1994 by P E Reavell SAM A43548one male one female Syzygium and Bridelia dominated swamp forest University of Zululand(28plusmn5102500S 31plusmn5100200E) coll 7 October 1996 by P E Reavell SAM A43549 one female Mdibiswamp forest Lake Msingazi catchment area north of Richards Bay (28plusmn420S 32plusmn090E) coll5 December 1996 by P E Reavell Albany Museum mdash GEN910 one female Mpolozi swampsMapelane (28plusmn2601300S 32plusmn2402500E) coll 13 February 1991 Albany Museum mdash GEN965 twomales ve females NrsquoKoninga Valley Richards Bay (28plusmn450S 32plusmn030E) coll 7 April 1988

Other material mdash The following specimens included in the collections of the South AfricanMuseum warrant further investigation as although they bear some resemblance to the speciesdescribed below their identi cation is uncertain SAM A41276 one male one female Mbonenidam Mkuze Game Reserve (27plusmn3705700S 32plusmn1504500E) coll 28 October 1994 by M Coke SAMA41299 two males Nxwala stream Mkuze Game Reserve (27plusmn4302300S 32plusmn1601000E) coll 10November 1994 by O Bourquin SAM A41277 one male Rainpool south of entrance False BayPark (28plusmn0000100S 32plusmn2102100E) coll 26 October 1994 by M Coke SAM A41300 two malesKangela rainpoolN2 near Mtubatuba (28plusmn2200000S 32plusmn1103600E) coll 25 October 1994 by M Cokeand SAM A41211 one male Ntambanana (Ntrabanana) Zululand coll by H H Curson

Type locality mdash South Africa KwaZulu-Natal Barringtonia and Ficus swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S32plusmn2401800E)

Distribution mdash At present known only from the swamp forests (characterizedby Barringtonia racemosa Syzygium cordatum and Ficus trichopoda vegetationand spongy hydromorphic peat-soil) in the vicinity of Richards Bay Empangeniand the Mapelane Nature Reserve It is probable that the distribution of the speciesmay extend into low-lying areas to the east of the Drakensberg escarpment in theprovince of Mpumalanga and into Mozambique

Etymology mdash From the Latin ldquolividusrdquo meaning ldquobluerdquo or ldquolight bluerdquoreferring to the characteristic silver-blue sheen of the carapace The epitheton isan adjective agreeing in gender with the (masculine) generic name

POTAMONAUTES LIVIDUS NOV 153

Fig 6 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A wholeanimal dorsal aspect B whole animal ventral aspect C cephalothorax frontal aspect

Diagnosis mdash Carapace distinctly vaulted and relatively narrow posteriorlyEpibranchial teeth absent and anterolateral margin of the carapace smooth Post-frontal crest indistinct medially with frontal lobe projecting downwards Cara-pace characteristically orange to red with silver-blue sheen Chelipeds and limbs

154 G GOUWS B A STEWART amp P E REAVELL

bright orange to red with lighter cheliped and dactyl tips Chela in ated and highlyarched

Description of male holotype mdash Size Measurements of the holotype and theranges of other specimens are given in table IV

Carapace ( gs 6A C 7A) Carapace and limbs characteristically orange tored with the carapace possessing a silver-blue sheen when alive Preserved spec-imens (70 ethanol) appear less orange and the carapace retains a blue-greycolour Cephalothorax ovoid distinctly vaulted branchial region highly convex( g 6A C) maximum height and width at anterior third (ratio CHCL D 065CWWCL D 145) Anterior margin straight Urogastric grooves moderately wellde ned Cardiac grooves shallow and poorly de ned Carapace otherwise smoothPostfrontal crest smooth curves forward medially Postfrontal crest diminishesabove inner orbit margins though well de ned immediately lateral to forked mid-point groove by means of two indentations anterior to crest indicating epigas-tric lobes Exorbital teeth moderately sharp but small Epibranchial teeth ab-sent Anterolateral margin posterior to postfrontal crest smooth margin curvingin over carapace in branchial region though indistinctly Each ank has a longitu-dinal groove dividing the subhepatic from the pterygostomial region with verticalgroove running from longitudinal groove joining anterolateral margin between ex-orbital tooth and postfrontal crest

Sternites ( gs 6B 7B) Sternites 1 and 2 fused no suture visible First suture(sternal groove) between sternites 2 and 3 complete Second sternal groove

TABLE IVPotamonautes lividus sp nov wet weight (in g) and measurements (in mm) for the male holotype

and ranges for other individuals examined (maximum of 77 males and 70 females)

Variable Abbreviation Holotype Males Females

Wet weight WW 242 05-214 07-183Carapace length CL 255 84-247 89-276Carapace widest width CWW 370 114-360 118-373Carapace posterior width CWP 281 90-269 86-306Distance between postfrontal crest

and anterior margin PFCD 43 12-222 15-46Distance between orbits ED 114 42-119 43-123Distance between exorbital teeth CWA 259 96-254 96-262Carapace height CH 165 48-171 50-162Width of sixth abdominal segment AW6 75 28-74 31-240Major cheliped propodus length MCPL 427 71-402 76-291Major cheliped propodus height MCPH 198 28-189 28-142Pereopod 2 merus length P2ML 189 50-181 51-171Pereopod 2 merus width P2MW 58 19-56 18-59

POTAMONAUTES LIVIDUS NOV 155

Fig 7 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A carapaceoutline B thoracic sternum C right cheliped dactylus and propodus D left cheliped dactylusand propodus E left third maxilliped F left mandible and mandibular palp posterior view G leftmandibular palp posterior view H left mandibular palp anterior view I left gonopod 1 anteriorview J terminal segment left gonopod 1 anterior view K left gonopod 1 posterior view L leftgonopod 2 anterior view Scale lines represent 1 mm except for A-D where they represent 10 mm

156 G GOUWS B A STEWART amp P E REAVELL

between sternites 3 and 4 complete laterally becoming shallower mediallysloping sharply towards abdominopelvic region

Third maxillipeds ( gs 6C 7E) Filling entire buccal frame except for ovalefferent respiratory openings short agellum present on exopods ischium smoothwith moderately deep vertical groove

Mandibular palp ( g 7F G H) Mandibular palp with two segments terminalsegment undivided with a dense tuft of setae on posterior surface of angeof terminal segment Margins generally hirsute Subterminal segment slightlyenlarged distally

Chelipeds and walking legs ( gs 6A 7C D) Chelipeds markedly unequaldactylus of right cheliped strongly arched 163 times length of dactylus of leftcheliped Both dactyli armed with up to 20 cutting teeth three to four of whichare slightly larger and more prominent Propodus of right cheliped markedlyin ated 168 times longer and 20 times wider than that of left cheliped Pollexpossesses 20 cutting teeth four to ve of which are more prominent Carpi ofboth chelipeds possess one prominent and three rudimentary teeth Margins ofmeri granulose small blunt spine on anterior surface no spine on anterior-inferiormargin Pereopods generally slender (pereopod 2 merus length width D 328 andpereopod 5 merus lengthwidth D 271) P3 longest P5 shortest ventral marginsof propodi and meri smooth dorsal margin with ne sharp bristles dactyli endingin sharp points with margins bearing a series of sharp spinelike bristles

Pleon ( gs 6B 7B) First ve segments broad and short last two segmentslonger terminal segment rounded at distal end

Pleopods ( g 7I J K) Pleopod 1 (gonopod 1) terminal segment short 025times length of subterminal segment terminal segment curves away from mid-line when viewed posteriorly widest at base ending in pointed tip Subterminalsegment of pleopod 1 tapers distally inner lateral margin slightly irregular outerlateral margin straighter both margins hirsute Posterior surface with twisting lon-gitudinal groove extending length of subterminal and terminal segment Groovenot visible on anterior surface Posterior surface and margins of groove hirsutePleopod 2 (gonopod 2) terminal segment lament-like 05 the length of subter-minal segment curving slightly towards medial line proximally curves away frommedial line distally ( g 7L) Subterminal segment widest at base tapering sharplyinwards at 04 of length forms narrow process supporting terminal segment

Variation mdash All individuals are characteristically dark orange to red witha silver-blue sheen to the carapace while the chelipeds vary in colour frombright orange-red to a lighter yellow-orange All individuals are characterized byhighly vaulted carapaces and downwardly projecting frontal lobes The postfrontalcrest which is most pronounced laterally (from directly above the orbits to theanterolateral margin) and incomplete medially is often more distinct in the smaller

POTAMONAUTES LIVIDUS NOV 157

individuals Chelipeds are not always typically arched enclosing a large ovoidspace as in the holotype Chelipeds of smaller individuals although in ated areless arched and often tight closing with the small cutting teeth more obviousChelipeds of females and small males in particular from the Mdibi and Universityof Zululand localities have propodi that are relatively high with in ated palmsand relatively short tightly closing chelae which project slightly downwardsHeterochely has been demonstrated in most Potamonautes-species occurring inSouth Africa (Siegfried 1972 Raubenheimer 1986 Stewart et al 1995 Stewart1997a b Stewart amp Cook 1998 Daniels et al 1998a Gouws et al 2000) Withinthe species 76 of the specimens were right-handed with 11 being left-handedand 13 being of equal or subequal (differing by less than one millimeter) sizeOf the males 79 were right-handed 8 left-handed and 13 equal or subequalFemales had 74 right-handedness 13 left-handedness and in 13 of caseschelipeds were equal or subequal The abdomen of mature females completelyoverlaps the coxae of the pereopods The smallest mature female had a CL of167 mm with the largest immature female having a CL of 159 indicating that thepubertal moult occurs approximately between the 14 mm and 18 mm size classes

Remarks mdash Potamonautes lividus sp nov can readily be distinguished from theten other species in the genus Potamonautes known to occur within South AfricaPotamonautes warreni Calman 1918 P dentatus P parvispina and P unispinusall bear a singular spine or a series of teeth on the anterolateral margins whereasP lividus sp nov is smooth Potamonautes perlatus P sidneyi and P granularisare all larger crabs with in ated arched carapaces with complete distinct post-frontal crests and scabrosity or granulation of the anterior margins orbits epi-branchial corners or postfrontal crests Potamonautes lividus sp nov has smoothcarapace margins and a incomplete postfrontal crest The terminal segment ofgonopod 1 in P lividus sp nov is relatively short and triangular and curves awayfrom the medial line when viewed posteriorly while that of P sidneyi is relativelylonger more slender and more S-shaped The postfrontal crest of P sidneyi mayjoin the anterolateral margin at a relatively sharp angle and form a pronouncedepibranchial corner along the anterolateral margin The anterolateral margin inP lividus sp nov is more rounded and the epibranchial corners slope down to-wards the anks Potamonautes granularis is chocolate brown with orange tips tothe chelipeds Potamonautes brincki is a smaller crab with a smoother carapacethough also chocolate to reddish-brown in colour with a nely granulated antero-lateral margin which does not curve in over the carapace in the branchial region(Stewart 1997b) Potamonautes depressus and P clarus both have rounded epi-branchial corners and smooth carapaces though these are relatively shallow andhave attened dorsal surfaces Both are characterized by long slender limbs Pota-monautes depressus is brown to green-brown in colour while P clarus is brightorange in colour

158 G GOUWS B A STEWART amp P E REAVELL

A number of species from further a eld bear a super cial resemblance toP lividus sp nov particularly with regard to carapace morphology though in mostcases they can be readily distinguished Potamonautes pilosus Hilgendorf 1898 isknown from East Africa and is a small crab with a CWW of less than 25 mmSpecimens possess a weak postfrontal crest which along with the anterolateralmargin can be granulated (Hilgendorf 1898 Bott 1955) Potamonautes neumanniHilgendorf 1898 is known from East Africa and has a characteristically vaultedcarapace without a complete distinct postfrontal crest (Hilgendorf 1898 Bott1955) The postfrontal crest is more distinct in P lividus particularly laterally andthe exorbital teeth are sharper and more de ned in P lividus than in P neumanniThe terminal segment of gonopod 1 is longer and more slender in P neumannithan in P lividus and curves distinctly outwards The subterminal segment ofgonopod 1 is wider at its apex in P neumanni than in P lividus Additionally thecarapace of preserved specimens of P neumanni is typically grey in colour whileliving specimens are violet in colour with bright olive-green limbs and chelipeds(Hilgendorf 1898) Potamonautes ballayi acristatus Bott 1955 has an incompletepostfrontal crest only present above the orbits and small and blunt exorbital teethThe major chela although highly arched and the minor chela are long and moreslender than those of P lividus sp nov The terminal segment of gonopod 1 ofP granviki Colosi 1924 is curved towards the medial line when viewed posteriorly(Bott 1955) The chelae of both P berardi berardi Audouin 1826 and P b ignestiiParisi 1923 are relatively short and high with stout downward-projecting ngersThe anterior margin of the frontal lobe of P b berardi shows a distinct invaginationand the anterolateral margin appears sharp and less rounded than in P lividus spnov while the postfrontal crest of P b ignestii is complete and has a fairly longmedial groove Potamonautes emini emini Hilgendorf 1892 are generally smallcrabs with a less in ated carapace and short stout chelipeds The subterminaland terminal segments of gonopod 1 are of more or less equal size (Bott 1955)Potamonautes e semilunaris Bott 1955 and P luashiensis Bott 1955 are alsosmall crabs (CWW lt 20 mm) with the postfrontal crest only visible laterally andin the case of P luashiensis the anterolateral margin and postfrontal crest mayshow granulation Potamonautes didieri Rathbun 1904 possesses a more completerounded postfrontal crest and shorter more stout chelipeds (Bott 1955)

ACKNOWLEDGEMENTS

Financial assistance was kindly provided by the World Wildlife Fund - SouthAfrica the Foundation for Research Development and the University of ZululandThe KwaZulu-Natal Nature Conservation Services provided accommodation and

POTAMONAUTES LIVIDUS NOV 159

logistic support Liz Hoenson Peter Cook Mike Coke and Tyrone Ridgway arethanked for assistance in the eld and Michelle van der Merwe is thanked foraiding in the photography and drafting of gures The authors wish to thank ananonymous reviewer for comments on the manuscript

REFERENCES

BARNARD K H 1935 Scienti c results of the Vernay-Lang Kalahari expedition March toSeptember 1930 Crustacea Ann Transvaal Mus 16 481-492

mdash mdash 1950 Descriptive catalogue of South African decapod Crustacea (crabs and shrimps) AnnSouth African Mus 38 1-837

BOCK W J 1986 Species concepts speciation and macroevolution In K IWATSUKIP H RAVEN amp W J BOCK (eds) Modern aspects of species 31-57 (University of TokyoPress Tokyo)

BOTT R 1955 Die Suumlsswasserkrabben von Afrika (Crust Decap) und ihre StammesgeschichteAnn Mus R Congo Belge (C Zool) 1 (33) 209-352 pls 1-30

BRUTON M N 1980 An outline of the ecology of the Mgobezeleni lake system at Sodwana withemphasis on the mangrove community In M N BRUTON amp K H COOPER (eds) Studieson the ecology of Maputaland 408-426 (Rhodes University Grahamstown)

CUMBERLIDGE N 1986 Ventilation of the branchial chambers in the amphibious West Africanfreshwater crab Sudanonautes (Convexonautes) aubryi monodi (Balss 1929) (BrachyuraPotamonautidae)Hydrobiol 134 53-65

mdash mdash 1991 The respiratory system of Globonautes macropus (Rathbun 1898) a terrestrialfreshwater crab from Liberia (GecarcinucoideaGecarcinucidae)Crustaceana 61 (1) 69-80

DANIELS S R B A STEWART amp M J GIBBONS 1998a Potamonautes granularis sp nov(Brachyura Potamonautidae) a new cryptic species of river crab from the Olifants Riversystem South Africa Crustaceana 71 (8) 885-903

mdash mdash mdash mdash amp mdash mdash 1998b Genetic and morphometric variation in the potamonautid river crabPotamonautes parvispina (Decapoda Potamonautidae) from two Western Cape rivers SouthAfrica Journ nat Hist London 32 1245-1258

mdash mdash mdash mdash amp mdash mdash 1999 Genetic structure among populations of Potamonautes perlatus(Decapoda Potamonautidae) from the Olifants River system in the Western Cape SouthAfrica Journ Zool London 249 (2) 137-142

DIacuteAZ H amp G RODRIacuteGUEZ 1977 The branchial chamber in terrestrial crabs a comparative studyBiol Bull Woods Hole 153 485-504

GOUWS G B A STEWART amp M COKE 2000 Evidence for a new species of river crab(Decapoda Brachyura Potamonautidae) from the Drakensberg South Africa Journ CrustBiol 20 (4) 743-758

GREENAWAY P amp H H TAYLOR 1976 Aerial gas exchange in Australian arid-zone crabParathelphusa transversa Von Martens Nature London 262 711-713

HILGENDORF F 1898 Die Land- und Suumlsswasser-Dekapoden Ostafrikas Die Thierwelt DeutschOst-Afrikas 4 (7) 1-37

LENZ H 1912 Afrikanische Crustaceen aus schwedischen Sammlungen Ark Zool 7 (29) 1-10MARKERT C L amp I FAULHABER 1965 Lactate dehydrogenase isozyme patterns of sh Journ

exp Zool 159 319-332MAYR E 1963 Animal species and evolution i-xiv 1-797 (Harvard University Press Cambridge

Massachusetts)mdash mdash 1970 Populations species and evolution i-xv 1-453 (Harvard University Press Cambridge

Massachusetts)

146 G GOUWS B A STEWART amp P E REAVELL

Three carapace variables (ED CH and CWP) contributed signi cantly to thediscrimination between the two forms in the discriminant function analysis Thehistogram plot of observed canonical variable scores ( g 3) clearly separates thetwo forms with the canonical variable means of the form A and form B individualscalculated at iexcl0996 and 1965 respectively The classi cation function (the linearfunction of variables which best discriminates the individuals of one group fromthe other speci ed groupings) was calculated for individuals of each form Theclassi cation function of the form A group was

Y D 306704 (Log CWP) iexcl 26103 (Log ED) iexcl 228513 (Log CH) iexcl 64156

and of the form B (P sidneyi) group

Y D 35097 (Log ED) iexcl 315543 (Log CH) C 347231 (Log CWP) iexcl 88367

Using the classi cation functions individuals were reassigned to groups basedon highest a posteriori probabilities Of the form A individuals 9437 (134of 142) were correctly classi ed with eight individuals being reassigned to theform B group Of the form B individuals 8889 were correctly reassigned to theP sidneyi group with eight of the 72 individuals being reassigned to the form Agroup

Fig 3 Histogram of scores for specimens of Potamonautes lividus sp nov (form A) and P sidneyiRathbun 1904 (form B) along the canonical variable calculated from a discriminant function

analysis using seven carapace variables

POTAMONAUTES LIVIDUS NOV 147

Comparison of regressions of the most discriminating variables between the twoforms regressed over CL in turn also showed signi cant differences between thetwo forms CH regressed over CL showed highly signi cant differences betweenthe two forms (SS D 0011 df D 1 F D 31266 P lt 0001) as did ED(SS D 0011 df D 1 F D 8333 P lt 0005) and CWP (SS D 0006 df D 1F D 8136 P lt 0005) These represent the most discriminating variables andtheir regressions are represented graphically ( g 4a b c) PFCD (SS D 0199df D 1 F D 52671 P lt 0001) CWW (SS D 0003 df D 1 F D 30963P lt 0001) and CWA (SS D 0001 df D 1 F D 6182 P lt 002) also showedthat there were signi cant differences between the two forms but the discriminantfunction analysis showed them to be redundant in constructing the model

Qualitative analysis mdash Examination of gonopods and mouthparts revealed onlyslight differences in gonopod morphology The terminal segment of gonopod 1of the undescribed form was relatively short and triangular whereas the terminalsegment of gonopod 1 of P sidneyi appears to be substantially longer and moreslender Although the terminal segment is bent away from the medial line in bothforms the terminal segment in P sidneyi possesses a lobe or ange that extendsinwards giving the terminal segment an S-shaped appearance The gonopods andmandibular palps of the two forms are illustrated in g 5

DISCUSSION

The data presented above clearly indicate that the two forms of freshwatercrabs from KwaZulu-Natal are distinct The form A specimens are smaller with amore vaulted carapace that is relatively narrower posteriorly and that possessesa relatively narrower frontal lobe (ED) than that of the Potamonautes sidneyiindividuals

Not only are the two forms clearly distinct both biochemically and morpho-logically but strong evidence suggests that they are reproductively isolated Thepresence of a diagnostic locus HEX xed for alternate alleles in the sympatricpopulation of the two forms indicates that a lack of gene ow and thus repro-ductive isolation exist between the two forms This allows for species recognitionunder the Biological Species Concept (Mayr 1970) under which species are de- ned as ldquogroups of actually or potentially interbreeding populations which arereproductively isolated from other such groupsrdquo (Mayr 1963 19) or ldquogeneticallyisolated (in nature) from other such groupsrdquo (Bock 1986 33) In his model of al-lopatric speciation Bock (1986) suggested that newly evolved species in sympatrywould exert mutually selective demands on each other by means of reproductive

148 G GOUWS B A STEWART amp P E REAVELL

Fig 4 Comparisons of the regressions of (A) Log CH (carapace height) over Log CL (carapacelength) (B) Log ED (eye distance) over Log CL and (C) Log CWP (posterior carapace width) overLog CL between form A (Potamonautes lividus sp nov) and form B (P sidneyi Rathbun 1904) All

differences are signi cant (at the P lt 0005 level)

POTAMONAUTES LIVIDUS NOV 149

Fig 5 A-E form A (Potamonautes lividus sp nov composite of male holotype SAM A43540and unaccessioned material) A carapace outline B left mandibular palp anterior view C leftmandibular palp posterior view D left gonopod 1 anterior view and E left gonopod 1 posteriorview F-J form B (Potamonautes sidneyi Rathbun 1904 unaccessioned specimen) F carapaceoutline G left mandibular palp anterior view H left mandibular palp posterior view I left

gonopod 1 anterior view J left gonopod 1 posterior view

150 G GOUWS B A STEWART amp P E REAVELL

interference and ecological competition This would lead to a divergence of mor-phological and behavioural aspects of feeding reproduction and other ecologicalfeatures The different gonopod morphologies of the two forms may re ect this

The three form A populations clustered separately from the three P sidneyipopulations at a I -value of 0829 Stewart (1997a) calculated the separationI -value between P parvispina Stewart 1997 and P perlatus H Milne Edwards1837 to be 068 An I -value of 066 separated both P perlatus and P brinckiBott 1960 in the Western Cape (Stewart 1997b) and P unispinus Stewart ampCook 1998 and P sidneyi in Mpumalanga (Stewart amp Cook 1998) An I -valueof 0599 was obtained separating P clarus Gouws Stewart amp Coke 2000 andP depressus (Gouws et al 2000) The only species in the genus delineated using ahigher I -value was P granularis Daniels Stewart amp Gibbons 1998 which wasseparated from P perlatus in the Olifants River at a I -value of 088 (Danielset al 1998a 1999) Although slightly higher than most interspeci c values inthe genus the value obtained in this study nevertheless falls within the range (035to 085) speci ed by Thorpe (1982) to indicate congeneric species differencesAllopatric populations showing I -values of less than 085 are unlikely to beconspeci c (Thorpe amp Soleacute-Cava 1994) With the exception of two cases allpairwise comparisons between allopatric populations of the two forms yieldedI -values less than 085

Identity-values were high for comparisons within both the form A (0949 to0986) and P sidneyi (0994 to 0999) groups Intraspeci c I -values are generallyhigh in the genus Potamonautes and disjunct populations within a species tendto be genetically undifferentiated Intraspeci c I -values obtained in six studies(Stewart 1997a b Stewart amp Cook 1998 Daniels et al 1998b 1999) involvingsix Potamonautes species varied from 0902 to 1000 (D D 0000 to 0103)An intraspeci c I -value of 075 was obtained in a comparison of two groups ofP brincki populations across the Cape Peninsula and Cape Flats However thismost probably indicates a species difference and requires further investigation(Stewart 1997b) Given the high intraspeci c I -values characteristic of the genusand those obtained for comparisons within each form the I -value obtainedfor the comparison between the two forms most likely represents a speciesdifference

Bock (1986) also de ned a species as possessing a set of three distinctcharacteristics genetic unity reproductive unity and ecological unity Biochemicaldata provide support for compliance with the rst two criteria for both formsWhile no empirical evidence is as yet available con rming the third factor adegree of macro- and microhabitat segregation and thus ecological segregationis evident between the two forms Potamonautes sidneyi is widespread acrossthe province (Stewart et al 1995) while the other form appears to have a

POTAMONAUTES LIVIDUS NOV 151

more limited distribution in northeastern KwaZulu-Natal restricted to patches ofswamp forest with particular oral assemblages The swamp forests are oftencharacterized by Barringtonia racemosa Syzygium cordatum Ficus trichopodaHibiscus tiliaceus L Rauvola caffra Sond Voacanga thouarsii Roem amp SchultRaphia australis Oberm amp Strey and Podocarpus falcatus (Thunb) R Br exMirb with the fern Stenochlaena tenuifolia (Desv) T Moore often present in theunderstorey (Bruton 1980 Moll 1980) Within the swamp forests the sympatricpopulations appear to show a degree of microhabitat segregation Observationssuggest that P sidneyi has a closer association with water as individuals were nevercollected great distances away from seepage pools and channels owing throughthe forest Conversely individuals of the swamp-forest form were most oftencollected farther from water and their burrows were often among the vegetationObservations suggest that this form is more terrestrial Individuals were noticedto move to higher elevations when the water table rose through the hydromorphicpeat soil ooding their burrows and the surface and they were also more active oncloudy overcast days Evidence of terrestrial adaptation is most likely to be foundin the structure and histology of the organs and tissues involved in respirationfactors such as branchial chamber shape and volume gill structure and formulaand the structure and vascularization of the branchiostegite lining are knownto re ect changes brought upon by the constraints of the terrestrial environment(Greenaway amp Taylor 1976 Diacuteaz amp Rodriacuteguez 1977 Taylor amp Greenaway1979 Cumberlidge 1986 1991 Takeda et al 1996) Although the availabilityof material prohibited the investigation of this aspect future research may prove tobe fruitful and highlight a greater distinction between the two forms

Studies on terrestrial adaptation supplemented by behavioural data that couldillustrate microhabitat and ecological segregation would quantify further thedegree of differentiation between the two forms However two independent datasets biochemical and morphological present strong evidence for the speci c statusof the swamp-forest form

TAXONOMY

Potamonautes lividus sp nov ( gs 6-7)

Material examined mdash Holotype South African Museum (SAM) A43540 one male CL D255 mm Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws andL Hoenson Allotype SAM A43541 one female CL D 245 mm Ficus and Barringtonia swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S 32plusmn2401800E)coll 27 January 1997 by B A Stewart G Gouws and L Hoenson Other material SAM A43542two males Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws

152 G GOUWS B A STEWART amp P E REAVELL

and L Hoenson SAM A43543 one female Lake Nhlabane north of Richards Bay (28plusmn3800500S32plusmn1601700E) coll 27 April 1993 by the University of Zululand Zoology Department SAMA43544 three males one female Mdibi swamp forest along Mdibi stream 8 km north of RichardsBay (28plusmn4202400S 32plusmn0902600E) coll 26 January 1997 by B A Stewart P A Cook M CokeP E Reavell G Gouws and L Hoenson SAM A43545 one male one female Syzygium forestUniversity of Zululand campus (28plusmn5102500S 31plusmn5100200E) coll 24 January 1997 by B A StewartP A Cook P E Reavell G Gouws and L Hoenson SAM A43546 two males two femalesUniversity of Zululand stream owing through campus (28plusmn550S 31plusmn410E) coll 10 September 1995by P E Reavell SAM A41313 one male one female swamp forest Empangeni (28plusmn5102500S31plusmn5100200E) coll 2 August 1994 by M Coke SAM A41155 one male University of ZululandSyzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S 31plusmn450E) coll 10 December1988 by P E Reavell SAM A41153 three males smaller holes in hydromorphic soil Syzygiumcordatum swamp forest University of Zululand (28plusmn450S 31plusmn450E) coll 20 March 1994 byP E Reavell SAM A41156 one female Syzygium cordatum swamp forest University of Zululand(28plusmn450S 31plusmn450E) coll 18 May 1992 by P E Reavell SAM A41154 one male one femaleUniversity of Zululand Syzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S31plusmn450E) coll 10 May 1990 by P E Reavell SAM A43547 two males one female swamp forestUniversity of Zululand (28plusmn450S 31plusmn450E) coll 1 April 1994 by P E Reavell SAM A43548one male one female Syzygium and Bridelia dominated swamp forest University of Zululand(28plusmn5102500S 31plusmn5100200E) coll 7 October 1996 by P E Reavell SAM A43549 one female Mdibiswamp forest Lake Msingazi catchment area north of Richards Bay (28plusmn420S 32plusmn090E) coll5 December 1996 by P E Reavell Albany Museum mdash GEN910 one female Mpolozi swampsMapelane (28plusmn2601300S 32plusmn2402500E) coll 13 February 1991 Albany Museum mdash GEN965 twomales ve females NrsquoKoninga Valley Richards Bay (28plusmn450S 32plusmn030E) coll 7 April 1988

Other material mdash The following specimens included in the collections of the South AfricanMuseum warrant further investigation as although they bear some resemblance to the speciesdescribed below their identi cation is uncertain SAM A41276 one male one female Mbonenidam Mkuze Game Reserve (27plusmn3705700S 32plusmn1504500E) coll 28 October 1994 by M Coke SAMA41299 two males Nxwala stream Mkuze Game Reserve (27plusmn4302300S 32plusmn1601000E) coll 10November 1994 by O Bourquin SAM A41277 one male Rainpool south of entrance False BayPark (28plusmn0000100S 32plusmn2102100E) coll 26 October 1994 by M Coke SAM A41300 two malesKangela rainpoolN2 near Mtubatuba (28plusmn2200000S 32plusmn1103600E) coll 25 October 1994 by M Cokeand SAM A41211 one male Ntambanana (Ntrabanana) Zululand coll by H H Curson

Type locality mdash South Africa KwaZulu-Natal Barringtonia and Ficus swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S32plusmn2401800E)

Distribution mdash At present known only from the swamp forests (characterizedby Barringtonia racemosa Syzygium cordatum and Ficus trichopoda vegetationand spongy hydromorphic peat-soil) in the vicinity of Richards Bay Empangeniand the Mapelane Nature Reserve It is probable that the distribution of the speciesmay extend into low-lying areas to the east of the Drakensberg escarpment in theprovince of Mpumalanga and into Mozambique

Etymology mdash From the Latin ldquolividusrdquo meaning ldquobluerdquo or ldquolight bluerdquoreferring to the characteristic silver-blue sheen of the carapace The epitheton isan adjective agreeing in gender with the (masculine) generic name

POTAMONAUTES LIVIDUS NOV 153

Fig 6 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A wholeanimal dorsal aspect B whole animal ventral aspect C cephalothorax frontal aspect

Diagnosis mdash Carapace distinctly vaulted and relatively narrow posteriorlyEpibranchial teeth absent and anterolateral margin of the carapace smooth Post-frontal crest indistinct medially with frontal lobe projecting downwards Cara-pace characteristically orange to red with silver-blue sheen Chelipeds and limbs

154 G GOUWS B A STEWART amp P E REAVELL

bright orange to red with lighter cheliped and dactyl tips Chela in ated and highlyarched

Description of male holotype mdash Size Measurements of the holotype and theranges of other specimens are given in table IV

Carapace ( gs 6A C 7A) Carapace and limbs characteristically orange tored with the carapace possessing a silver-blue sheen when alive Preserved spec-imens (70 ethanol) appear less orange and the carapace retains a blue-greycolour Cephalothorax ovoid distinctly vaulted branchial region highly convex( g 6A C) maximum height and width at anterior third (ratio CHCL D 065CWWCL D 145) Anterior margin straight Urogastric grooves moderately wellde ned Cardiac grooves shallow and poorly de ned Carapace otherwise smoothPostfrontal crest smooth curves forward medially Postfrontal crest diminishesabove inner orbit margins though well de ned immediately lateral to forked mid-point groove by means of two indentations anterior to crest indicating epigas-tric lobes Exorbital teeth moderately sharp but small Epibranchial teeth ab-sent Anterolateral margin posterior to postfrontal crest smooth margin curvingin over carapace in branchial region though indistinctly Each ank has a longitu-dinal groove dividing the subhepatic from the pterygostomial region with verticalgroove running from longitudinal groove joining anterolateral margin between ex-orbital tooth and postfrontal crest

Sternites ( gs 6B 7B) Sternites 1 and 2 fused no suture visible First suture(sternal groove) between sternites 2 and 3 complete Second sternal groove

TABLE IVPotamonautes lividus sp nov wet weight (in g) and measurements (in mm) for the male holotype

and ranges for other individuals examined (maximum of 77 males and 70 females)

Variable Abbreviation Holotype Males Females

Wet weight WW 242 05-214 07-183Carapace length CL 255 84-247 89-276Carapace widest width CWW 370 114-360 118-373Carapace posterior width CWP 281 90-269 86-306Distance between postfrontal crest

and anterior margin PFCD 43 12-222 15-46Distance between orbits ED 114 42-119 43-123Distance between exorbital teeth CWA 259 96-254 96-262Carapace height CH 165 48-171 50-162Width of sixth abdominal segment AW6 75 28-74 31-240Major cheliped propodus length MCPL 427 71-402 76-291Major cheliped propodus height MCPH 198 28-189 28-142Pereopod 2 merus length P2ML 189 50-181 51-171Pereopod 2 merus width P2MW 58 19-56 18-59

POTAMONAUTES LIVIDUS NOV 155

Fig 7 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A carapaceoutline B thoracic sternum C right cheliped dactylus and propodus D left cheliped dactylusand propodus E left third maxilliped F left mandible and mandibular palp posterior view G leftmandibular palp posterior view H left mandibular palp anterior view I left gonopod 1 anteriorview J terminal segment left gonopod 1 anterior view K left gonopod 1 posterior view L leftgonopod 2 anterior view Scale lines represent 1 mm except for A-D where they represent 10 mm

156 G GOUWS B A STEWART amp P E REAVELL

between sternites 3 and 4 complete laterally becoming shallower mediallysloping sharply towards abdominopelvic region

Third maxillipeds ( gs 6C 7E) Filling entire buccal frame except for ovalefferent respiratory openings short agellum present on exopods ischium smoothwith moderately deep vertical groove

Mandibular palp ( g 7F G H) Mandibular palp with two segments terminalsegment undivided with a dense tuft of setae on posterior surface of angeof terminal segment Margins generally hirsute Subterminal segment slightlyenlarged distally

Chelipeds and walking legs ( gs 6A 7C D) Chelipeds markedly unequaldactylus of right cheliped strongly arched 163 times length of dactylus of leftcheliped Both dactyli armed with up to 20 cutting teeth three to four of whichare slightly larger and more prominent Propodus of right cheliped markedlyin ated 168 times longer and 20 times wider than that of left cheliped Pollexpossesses 20 cutting teeth four to ve of which are more prominent Carpi ofboth chelipeds possess one prominent and three rudimentary teeth Margins ofmeri granulose small blunt spine on anterior surface no spine on anterior-inferiormargin Pereopods generally slender (pereopod 2 merus length width D 328 andpereopod 5 merus lengthwidth D 271) P3 longest P5 shortest ventral marginsof propodi and meri smooth dorsal margin with ne sharp bristles dactyli endingin sharp points with margins bearing a series of sharp spinelike bristles

Pleon ( gs 6B 7B) First ve segments broad and short last two segmentslonger terminal segment rounded at distal end

Pleopods ( g 7I J K) Pleopod 1 (gonopod 1) terminal segment short 025times length of subterminal segment terminal segment curves away from mid-line when viewed posteriorly widest at base ending in pointed tip Subterminalsegment of pleopod 1 tapers distally inner lateral margin slightly irregular outerlateral margin straighter both margins hirsute Posterior surface with twisting lon-gitudinal groove extending length of subterminal and terminal segment Groovenot visible on anterior surface Posterior surface and margins of groove hirsutePleopod 2 (gonopod 2) terminal segment lament-like 05 the length of subter-minal segment curving slightly towards medial line proximally curves away frommedial line distally ( g 7L) Subterminal segment widest at base tapering sharplyinwards at 04 of length forms narrow process supporting terminal segment

Variation mdash All individuals are characteristically dark orange to red witha silver-blue sheen to the carapace while the chelipeds vary in colour frombright orange-red to a lighter yellow-orange All individuals are characterized byhighly vaulted carapaces and downwardly projecting frontal lobes The postfrontalcrest which is most pronounced laterally (from directly above the orbits to theanterolateral margin) and incomplete medially is often more distinct in the smaller

POTAMONAUTES LIVIDUS NOV 157

individuals Chelipeds are not always typically arched enclosing a large ovoidspace as in the holotype Chelipeds of smaller individuals although in ated areless arched and often tight closing with the small cutting teeth more obviousChelipeds of females and small males in particular from the Mdibi and Universityof Zululand localities have propodi that are relatively high with in ated palmsand relatively short tightly closing chelae which project slightly downwardsHeterochely has been demonstrated in most Potamonautes-species occurring inSouth Africa (Siegfried 1972 Raubenheimer 1986 Stewart et al 1995 Stewart1997a b Stewart amp Cook 1998 Daniels et al 1998a Gouws et al 2000) Withinthe species 76 of the specimens were right-handed with 11 being left-handedand 13 being of equal or subequal (differing by less than one millimeter) sizeOf the males 79 were right-handed 8 left-handed and 13 equal or subequalFemales had 74 right-handedness 13 left-handedness and in 13 of caseschelipeds were equal or subequal The abdomen of mature females completelyoverlaps the coxae of the pereopods The smallest mature female had a CL of167 mm with the largest immature female having a CL of 159 indicating that thepubertal moult occurs approximately between the 14 mm and 18 mm size classes

Remarks mdash Potamonautes lividus sp nov can readily be distinguished from theten other species in the genus Potamonautes known to occur within South AfricaPotamonautes warreni Calman 1918 P dentatus P parvispina and P unispinusall bear a singular spine or a series of teeth on the anterolateral margins whereasP lividus sp nov is smooth Potamonautes perlatus P sidneyi and P granularisare all larger crabs with in ated arched carapaces with complete distinct post-frontal crests and scabrosity or granulation of the anterior margins orbits epi-branchial corners or postfrontal crests Potamonautes lividus sp nov has smoothcarapace margins and a incomplete postfrontal crest The terminal segment ofgonopod 1 in P lividus sp nov is relatively short and triangular and curves awayfrom the medial line when viewed posteriorly while that of P sidneyi is relativelylonger more slender and more S-shaped The postfrontal crest of P sidneyi mayjoin the anterolateral margin at a relatively sharp angle and form a pronouncedepibranchial corner along the anterolateral margin The anterolateral margin inP lividus sp nov is more rounded and the epibranchial corners slope down to-wards the anks Potamonautes granularis is chocolate brown with orange tips tothe chelipeds Potamonautes brincki is a smaller crab with a smoother carapacethough also chocolate to reddish-brown in colour with a nely granulated antero-lateral margin which does not curve in over the carapace in the branchial region(Stewart 1997b) Potamonautes depressus and P clarus both have rounded epi-branchial corners and smooth carapaces though these are relatively shallow andhave attened dorsal surfaces Both are characterized by long slender limbs Pota-monautes depressus is brown to green-brown in colour while P clarus is brightorange in colour

158 G GOUWS B A STEWART amp P E REAVELL

A number of species from further a eld bear a super cial resemblance toP lividus sp nov particularly with regard to carapace morphology though in mostcases they can be readily distinguished Potamonautes pilosus Hilgendorf 1898 isknown from East Africa and is a small crab with a CWW of less than 25 mmSpecimens possess a weak postfrontal crest which along with the anterolateralmargin can be granulated (Hilgendorf 1898 Bott 1955) Potamonautes neumanniHilgendorf 1898 is known from East Africa and has a characteristically vaultedcarapace without a complete distinct postfrontal crest (Hilgendorf 1898 Bott1955) The postfrontal crest is more distinct in P lividus particularly laterally andthe exorbital teeth are sharper and more de ned in P lividus than in P neumanniThe terminal segment of gonopod 1 is longer and more slender in P neumannithan in P lividus and curves distinctly outwards The subterminal segment ofgonopod 1 is wider at its apex in P neumanni than in P lividus Additionally thecarapace of preserved specimens of P neumanni is typically grey in colour whileliving specimens are violet in colour with bright olive-green limbs and chelipeds(Hilgendorf 1898) Potamonautes ballayi acristatus Bott 1955 has an incompletepostfrontal crest only present above the orbits and small and blunt exorbital teethThe major chela although highly arched and the minor chela are long and moreslender than those of P lividus sp nov The terminal segment of gonopod 1 ofP granviki Colosi 1924 is curved towards the medial line when viewed posteriorly(Bott 1955) The chelae of both P berardi berardi Audouin 1826 and P b ignestiiParisi 1923 are relatively short and high with stout downward-projecting ngersThe anterior margin of the frontal lobe of P b berardi shows a distinct invaginationand the anterolateral margin appears sharp and less rounded than in P lividus spnov while the postfrontal crest of P b ignestii is complete and has a fairly longmedial groove Potamonautes emini emini Hilgendorf 1892 are generally smallcrabs with a less in ated carapace and short stout chelipeds The subterminaland terminal segments of gonopod 1 are of more or less equal size (Bott 1955)Potamonautes e semilunaris Bott 1955 and P luashiensis Bott 1955 are alsosmall crabs (CWW lt 20 mm) with the postfrontal crest only visible laterally andin the case of P luashiensis the anterolateral margin and postfrontal crest mayshow granulation Potamonautes didieri Rathbun 1904 possesses a more completerounded postfrontal crest and shorter more stout chelipeds (Bott 1955)

ACKNOWLEDGEMENTS

Financial assistance was kindly provided by the World Wildlife Fund - SouthAfrica the Foundation for Research Development and the University of ZululandThe KwaZulu-Natal Nature Conservation Services provided accommodation and

POTAMONAUTES LIVIDUS NOV 159

logistic support Liz Hoenson Peter Cook Mike Coke and Tyrone Ridgway arethanked for assistance in the eld and Michelle van der Merwe is thanked foraiding in the photography and drafting of gures The authors wish to thank ananonymous reviewer for comments on the manuscript

REFERENCES

BARNARD K H 1935 Scienti c results of the Vernay-Lang Kalahari expedition March toSeptember 1930 Crustacea Ann Transvaal Mus 16 481-492

mdash mdash 1950 Descriptive catalogue of South African decapod Crustacea (crabs and shrimps) AnnSouth African Mus 38 1-837

BOCK W J 1986 Species concepts speciation and macroevolution In K IWATSUKIP H RAVEN amp W J BOCK (eds) Modern aspects of species 31-57 (University of TokyoPress Tokyo)

BOTT R 1955 Die Suumlsswasserkrabben von Afrika (Crust Decap) und ihre StammesgeschichteAnn Mus R Congo Belge (C Zool) 1 (33) 209-352 pls 1-30

BRUTON M N 1980 An outline of the ecology of the Mgobezeleni lake system at Sodwana withemphasis on the mangrove community In M N BRUTON amp K H COOPER (eds) Studieson the ecology of Maputaland 408-426 (Rhodes University Grahamstown)

CUMBERLIDGE N 1986 Ventilation of the branchial chambers in the amphibious West Africanfreshwater crab Sudanonautes (Convexonautes) aubryi monodi (Balss 1929) (BrachyuraPotamonautidae)Hydrobiol 134 53-65

mdash mdash 1991 The respiratory system of Globonautes macropus (Rathbun 1898) a terrestrialfreshwater crab from Liberia (GecarcinucoideaGecarcinucidae)Crustaceana 61 (1) 69-80

DANIELS S R B A STEWART amp M J GIBBONS 1998a Potamonautes granularis sp nov(Brachyura Potamonautidae) a new cryptic species of river crab from the Olifants Riversystem South Africa Crustaceana 71 (8) 885-903

mdash mdash mdash mdash amp mdash mdash 1998b Genetic and morphometric variation in the potamonautid river crabPotamonautes parvispina (Decapoda Potamonautidae) from two Western Cape rivers SouthAfrica Journ nat Hist London 32 1245-1258

mdash mdash mdash mdash amp mdash mdash 1999 Genetic structure among populations of Potamonautes perlatus(Decapoda Potamonautidae) from the Olifants River system in the Western Cape SouthAfrica Journ Zool London 249 (2) 137-142

DIacuteAZ H amp G RODRIacuteGUEZ 1977 The branchial chamber in terrestrial crabs a comparative studyBiol Bull Woods Hole 153 485-504

GOUWS G B A STEWART amp M COKE 2000 Evidence for a new species of river crab(Decapoda Brachyura Potamonautidae) from the Drakensberg South Africa Journ CrustBiol 20 (4) 743-758

GREENAWAY P amp H H TAYLOR 1976 Aerial gas exchange in Australian arid-zone crabParathelphusa transversa Von Martens Nature London 262 711-713

HILGENDORF F 1898 Die Land- und Suumlsswasser-Dekapoden Ostafrikas Die Thierwelt DeutschOst-Afrikas 4 (7) 1-37

LENZ H 1912 Afrikanische Crustaceen aus schwedischen Sammlungen Ark Zool 7 (29) 1-10MARKERT C L amp I FAULHABER 1965 Lactate dehydrogenase isozyme patterns of sh Journ

exp Zool 159 319-332MAYR E 1963 Animal species and evolution i-xiv 1-797 (Harvard University Press Cambridge

Massachusetts)mdash mdash 1970 Populations species and evolution i-xv 1-453 (Harvard University Press Cambridge

Massachusetts)

POTAMONAUTES LIVIDUS NOV 147

Comparison of regressions of the most discriminating variables between the twoforms regressed over CL in turn also showed signi cant differences between thetwo forms CH regressed over CL showed highly signi cant differences betweenthe two forms (SS D 0011 df D 1 F D 31266 P lt 0001) as did ED(SS D 0011 df D 1 F D 8333 P lt 0005) and CWP (SS D 0006 df D 1F D 8136 P lt 0005) These represent the most discriminating variables andtheir regressions are represented graphically ( g 4a b c) PFCD (SS D 0199df D 1 F D 52671 P lt 0001) CWW (SS D 0003 df D 1 F D 30963P lt 0001) and CWA (SS D 0001 df D 1 F D 6182 P lt 002) also showedthat there were signi cant differences between the two forms but the discriminantfunction analysis showed them to be redundant in constructing the model

Qualitative analysis mdash Examination of gonopods and mouthparts revealed onlyslight differences in gonopod morphology The terminal segment of gonopod 1of the undescribed form was relatively short and triangular whereas the terminalsegment of gonopod 1 of P sidneyi appears to be substantially longer and moreslender Although the terminal segment is bent away from the medial line in bothforms the terminal segment in P sidneyi possesses a lobe or ange that extendsinwards giving the terminal segment an S-shaped appearance The gonopods andmandibular palps of the two forms are illustrated in g 5

DISCUSSION

The data presented above clearly indicate that the two forms of freshwatercrabs from KwaZulu-Natal are distinct The form A specimens are smaller with amore vaulted carapace that is relatively narrower posteriorly and that possessesa relatively narrower frontal lobe (ED) than that of the Potamonautes sidneyiindividuals

Not only are the two forms clearly distinct both biochemically and morpho-logically but strong evidence suggests that they are reproductively isolated Thepresence of a diagnostic locus HEX xed for alternate alleles in the sympatricpopulation of the two forms indicates that a lack of gene ow and thus repro-ductive isolation exist between the two forms This allows for species recognitionunder the Biological Species Concept (Mayr 1970) under which species are de- ned as ldquogroups of actually or potentially interbreeding populations which arereproductively isolated from other such groupsrdquo (Mayr 1963 19) or ldquogeneticallyisolated (in nature) from other such groupsrdquo (Bock 1986 33) In his model of al-lopatric speciation Bock (1986) suggested that newly evolved species in sympatrywould exert mutually selective demands on each other by means of reproductive

148 G GOUWS B A STEWART amp P E REAVELL

Fig 4 Comparisons of the regressions of (A) Log CH (carapace height) over Log CL (carapacelength) (B) Log ED (eye distance) over Log CL and (C) Log CWP (posterior carapace width) overLog CL between form A (Potamonautes lividus sp nov) and form B (P sidneyi Rathbun 1904) All

differences are signi cant (at the P lt 0005 level)

POTAMONAUTES LIVIDUS NOV 149

Fig 5 A-E form A (Potamonautes lividus sp nov composite of male holotype SAM A43540and unaccessioned material) A carapace outline B left mandibular palp anterior view C leftmandibular palp posterior view D left gonopod 1 anterior view and E left gonopod 1 posteriorview F-J form B (Potamonautes sidneyi Rathbun 1904 unaccessioned specimen) F carapaceoutline G left mandibular palp anterior view H left mandibular palp posterior view I left

gonopod 1 anterior view J left gonopod 1 posterior view

150 G GOUWS B A STEWART amp P E REAVELL

interference and ecological competition This would lead to a divergence of mor-phological and behavioural aspects of feeding reproduction and other ecologicalfeatures The different gonopod morphologies of the two forms may re ect this

The three form A populations clustered separately from the three P sidneyipopulations at a I -value of 0829 Stewart (1997a) calculated the separationI -value between P parvispina Stewart 1997 and P perlatus H Milne Edwards1837 to be 068 An I -value of 066 separated both P perlatus and P brinckiBott 1960 in the Western Cape (Stewart 1997b) and P unispinus Stewart ampCook 1998 and P sidneyi in Mpumalanga (Stewart amp Cook 1998) An I -valueof 0599 was obtained separating P clarus Gouws Stewart amp Coke 2000 andP depressus (Gouws et al 2000) The only species in the genus delineated using ahigher I -value was P granularis Daniels Stewart amp Gibbons 1998 which wasseparated from P perlatus in the Olifants River at a I -value of 088 (Danielset al 1998a 1999) Although slightly higher than most interspeci c values inthe genus the value obtained in this study nevertheless falls within the range (035to 085) speci ed by Thorpe (1982) to indicate congeneric species differencesAllopatric populations showing I -values of less than 085 are unlikely to beconspeci c (Thorpe amp Soleacute-Cava 1994) With the exception of two cases allpairwise comparisons between allopatric populations of the two forms yieldedI -values less than 085

Identity-values were high for comparisons within both the form A (0949 to0986) and P sidneyi (0994 to 0999) groups Intraspeci c I -values are generallyhigh in the genus Potamonautes and disjunct populations within a species tendto be genetically undifferentiated Intraspeci c I -values obtained in six studies(Stewart 1997a b Stewart amp Cook 1998 Daniels et al 1998b 1999) involvingsix Potamonautes species varied from 0902 to 1000 (D D 0000 to 0103)An intraspeci c I -value of 075 was obtained in a comparison of two groups ofP brincki populations across the Cape Peninsula and Cape Flats However thismost probably indicates a species difference and requires further investigation(Stewart 1997b) Given the high intraspeci c I -values characteristic of the genusand those obtained for comparisons within each form the I -value obtainedfor the comparison between the two forms most likely represents a speciesdifference

Bock (1986) also de ned a species as possessing a set of three distinctcharacteristics genetic unity reproductive unity and ecological unity Biochemicaldata provide support for compliance with the rst two criteria for both formsWhile no empirical evidence is as yet available con rming the third factor adegree of macro- and microhabitat segregation and thus ecological segregationis evident between the two forms Potamonautes sidneyi is widespread acrossthe province (Stewart et al 1995) while the other form appears to have a

POTAMONAUTES LIVIDUS NOV 151

more limited distribution in northeastern KwaZulu-Natal restricted to patches ofswamp forest with particular oral assemblages The swamp forests are oftencharacterized by Barringtonia racemosa Syzygium cordatum Ficus trichopodaHibiscus tiliaceus L Rauvola caffra Sond Voacanga thouarsii Roem amp SchultRaphia australis Oberm amp Strey and Podocarpus falcatus (Thunb) R Br exMirb with the fern Stenochlaena tenuifolia (Desv) T Moore often present in theunderstorey (Bruton 1980 Moll 1980) Within the swamp forests the sympatricpopulations appear to show a degree of microhabitat segregation Observationssuggest that P sidneyi has a closer association with water as individuals were nevercollected great distances away from seepage pools and channels owing throughthe forest Conversely individuals of the swamp-forest form were most oftencollected farther from water and their burrows were often among the vegetationObservations suggest that this form is more terrestrial Individuals were noticedto move to higher elevations when the water table rose through the hydromorphicpeat soil ooding their burrows and the surface and they were also more active oncloudy overcast days Evidence of terrestrial adaptation is most likely to be foundin the structure and histology of the organs and tissues involved in respirationfactors such as branchial chamber shape and volume gill structure and formulaand the structure and vascularization of the branchiostegite lining are knownto re ect changes brought upon by the constraints of the terrestrial environment(Greenaway amp Taylor 1976 Diacuteaz amp Rodriacuteguez 1977 Taylor amp Greenaway1979 Cumberlidge 1986 1991 Takeda et al 1996) Although the availabilityof material prohibited the investigation of this aspect future research may prove tobe fruitful and highlight a greater distinction between the two forms

Studies on terrestrial adaptation supplemented by behavioural data that couldillustrate microhabitat and ecological segregation would quantify further thedegree of differentiation between the two forms However two independent datasets biochemical and morphological present strong evidence for the speci c statusof the swamp-forest form

TAXONOMY

Potamonautes lividus sp nov ( gs 6-7)

Material examined mdash Holotype South African Museum (SAM) A43540 one male CL D255 mm Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws andL Hoenson Allotype SAM A43541 one female CL D 245 mm Ficus and Barringtonia swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S 32plusmn2401800E)coll 27 January 1997 by B A Stewart G Gouws and L Hoenson Other material SAM A43542two males Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws

152 G GOUWS B A STEWART amp P E REAVELL

and L Hoenson SAM A43543 one female Lake Nhlabane north of Richards Bay (28plusmn3800500S32plusmn1601700E) coll 27 April 1993 by the University of Zululand Zoology Department SAMA43544 three males one female Mdibi swamp forest along Mdibi stream 8 km north of RichardsBay (28plusmn4202400S 32plusmn0902600E) coll 26 January 1997 by B A Stewart P A Cook M CokeP E Reavell G Gouws and L Hoenson SAM A43545 one male one female Syzygium forestUniversity of Zululand campus (28plusmn5102500S 31plusmn5100200E) coll 24 January 1997 by B A StewartP A Cook P E Reavell G Gouws and L Hoenson SAM A43546 two males two femalesUniversity of Zululand stream owing through campus (28plusmn550S 31plusmn410E) coll 10 September 1995by P E Reavell SAM A41313 one male one female swamp forest Empangeni (28plusmn5102500S31plusmn5100200E) coll 2 August 1994 by M Coke SAM A41155 one male University of ZululandSyzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S 31plusmn450E) coll 10 December1988 by P E Reavell SAM A41153 three males smaller holes in hydromorphic soil Syzygiumcordatum swamp forest University of Zululand (28plusmn450S 31plusmn450E) coll 20 March 1994 byP E Reavell SAM A41156 one female Syzygium cordatum swamp forest University of Zululand(28plusmn450S 31plusmn450E) coll 18 May 1992 by P E Reavell SAM A41154 one male one femaleUniversity of Zululand Syzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S31plusmn450E) coll 10 May 1990 by P E Reavell SAM A43547 two males one female swamp forestUniversity of Zululand (28plusmn450S 31plusmn450E) coll 1 April 1994 by P E Reavell SAM A43548one male one female Syzygium and Bridelia dominated swamp forest University of Zululand(28plusmn5102500S 31plusmn5100200E) coll 7 October 1996 by P E Reavell SAM A43549 one female Mdibiswamp forest Lake Msingazi catchment area north of Richards Bay (28plusmn420S 32plusmn090E) coll5 December 1996 by P E Reavell Albany Museum mdash GEN910 one female Mpolozi swampsMapelane (28plusmn2601300S 32plusmn2402500E) coll 13 February 1991 Albany Museum mdash GEN965 twomales ve females NrsquoKoninga Valley Richards Bay (28plusmn450S 32plusmn030E) coll 7 April 1988

Other material mdash The following specimens included in the collections of the South AfricanMuseum warrant further investigation as although they bear some resemblance to the speciesdescribed below their identi cation is uncertain SAM A41276 one male one female Mbonenidam Mkuze Game Reserve (27plusmn3705700S 32plusmn1504500E) coll 28 October 1994 by M Coke SAMA41299 two males Nxwala stream Mkuze Game Reserve (27plusmn4302300S 32plusmn1601000E) coll 10November 1994 by O Bourquin SAM A41277 one male Rainpool south of entrance False BayPark (28plusmn0000100S 32plusmn2102100E) coll 26 October 1994 by M Coke SAM A41300 two malesKangela rainpoolN2 near Mtubatuba (28plusmn2200000S 32plusmn1103600E) coll 25 October 1994 by M Cokeand SAM A41211 one male Ntambanana (Ntrabanana) Zululand coll by H H Curson

Type locality mdash South Africa KwaZulu-Natal Barringtonia and Ficus swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S32plusmn2401800E)

Distribution mdash At present known only from the swamp forests (characterizedby Barringtonia racemosa Syzygium cordatum and Ficus trichopoda vegetationand spongy hydromorphic peat-soil) in the vicinity of Richards Bay Empangeniand the Mapelane Nature Reserve It is probable that the distribution of the speciesmay extend into low-lying areas to the east of the Drakensberg escarpment in theprovince of Mpumalanga and into Mozambique

Etymology mdash From the Latin ldquolividusrdquo meaning ldquobluerdquo or ldquolight bluerdquoreferring to the characteristic silver-blue sheen of the carapace The epitheton isan adjective agreeing in gender with the (masculine) generic name

POTAMONAUTES LIVIDUS NOV 153

Fig 6 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A wholeanimal dorsal aspect B whole animal ventral aspect C cephalothorax frontal aspect

Diagnosis mdash Carapace distinctly vaulted and relatively narrow posteriorlyEpibranchial teeth absent and anterolateral margin of the carapace smooth Post-frontal crest indistinct medially with frontal lobe projecting downwards Cara-pace characteristically orange to red with silver-blue sheen Chelipeds and limbs

154 G GOUWS B A STEWART amp P E REAVELL

bright orange to red with lighter cheliped and dactyl tips Chela in ated and highlyarched

Description of male holotype mdash Size Measurements of the holotype and theranges of other specimens are given in table IV

Carapace ( gs 6A C 7A) Carapace and limbs characteristically orange tored with the carapace possessing a silver-blue sheen when alive Preserved spec-imens (70 ethanol) appear less orange and the carapace retains a blue-greycolour Cephalothorax ovoid distinctly vaulted branchial region highly convex( g 6A C) maximum height and width at anterior third (ratio CHCL D 065CWWCL D 145) Anterior margin straight Urogastric grooves moderately wellde ned Cardiac grooves shallow and poorly de ned Carapace otherwise smoothPostfrontal crest smooth curves forward medially Postfrontal crest diminishesabove inner orbit margins though well de ned immediately lateral to forked mid-point groove by means of two indentations anterior to crest indicating epigas-tric lobes Exorbital teeth moderately sharp but small Epibranchial teeth ab-sent Anterolateral margin posterior to postfrontal crest smooth margin curvingin over carapace in branchial region though indistinctly Each ank has a longitu-dinal groove dividing the subhepatic from the pterygostomial region with verticalgroove running from longitudinal groove joining anterolateral margin between ex-orbital tooth and postfrontal crest

Sternites ( gs 6B 7B) Sternites 1 and 2 fused no suture visible First suture(sternal groove) between sternites 2 and 3 complete Second sternal groove

TABLE IVPotamonautes lividus sp nov wet weight (in g) and measurements (in mm) for the male holotype

and ranges for other individuals examined (maximum of 77 males and 70 females)

Variable Abbreviation Holotype Males Females

Wet weight WW 242 05-214 07-183Carapace length CL 255 84-247 89-276Carapace widest width CWW 370 114-360 118-373Carapace posterior width CWP 281 90-269 86-306Distance between postfrontal crest

and anterior margin PFCD 43 12-222 15-46Distance between orbits ED 114 42-119 43-123Distance between exorbital teeth CWA 259 96-254 96-262Carapace height CH 165 48-171 50-162Width of sixth abdominal segment AW6 75 28-74 31-240Major cheliped propodus length MCPL 427 71-402 76-291Major cheliped propodus height MCPH 198 28-189 28-142Pereopod 2 merus length P2ML 189 50-181 51-171Pereopod 2 merus width P2MW 58 19-56 18-59

POTAMONAUTES LIVIDUS NOV 155

Fig 7 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A carapaceoutline B thoracic sternum C right cheliped dactylus and propodus D left cheliped dactylusand propodus E left third maxilliped F left mandible and mandibular palp posterior view G leftmandibular palp posterior view H left mandibular palp anterior view I left gonopod 1 anteriorview J terminal segment left gonopod 1 anterior view K left gonopod 1 posterior view L leftgonopod 2 anterior view Scale lines represent 1 mm except for A-D where they represent 10 mm

156 G GOUWS B A STEWART amp P E REAVELL

between sternites 3 and 4 complete laterally becoming shallower mediallysloping sharply towards abdominopelvic region

Third maxillipeds ( gs 6C 7E) Filling entire buccal frame except for ovalefferent respiratory openings short agellum present on exopods ischium smoothwith moderately deep vertical groove

Mandibular palp ( g 7F G H) Mandibular palp with two segments terminalsegment undivided with a dense tuft of setae on posterior surface of angeof terminal segment Margins generally hirsute Subterminal segment slightlyenlarged distally

Chelipeds and walking legs ( gs 6A 7C D) Chelipeds markedly unequaldactylus of right cheliped strongly arched 163 times length of dactylus of leftcheliped Both dactyli armed with up to 20 cutting teeth three to four of whichare slightly larger and more prominent Propodus of right cheliped markedlyin ated 168 times longer and 20 times wider than that of left cheliped Pollexpossesses 20 cutting teeth four to ve of which are more prominent Carpi ofboth chelipeds possess one prominent and three rudimentary teeth Margins ofmeri granulose small blunt spine on anterior surface no spine on anterior-inferiormargin Pereopods generally slender (pereopod 2 merus length width D 328 andpereopod 5 merus lengthwidth D 271) P3 longest P5 shortest ventral marginsof propodi and meri smooth dorsal margin with ne sharp bristles dactyli endingin sharp points with margins bearing a series of sharp spinelike bristles

Pleon ( gs 6B 7B) First ve segments broad and short last two segmentslonger terminal segment rounded at distal end

Pleopods ( g 7I J K) Pleopod 1 (gonopod 1) terminal segment short 025times length of subterminal segment terminal segment curves away from mid-line when viewed posteriorly widest at base ending in pointed tip Subterminalsegment of pleopod 1 tapers distally inner lateral margin slightly irregular outerlateral margin straighter both margins hirsute Posterior surface with twisting lon-gitudinal groove extending length of subterminal and terminal segment Groovenot visible on anterior surface Posterior surface and margins of groove hirsutePleopod 2 (gonopod 2) terminal segment lament-like 05 the length of subter-minal segment curving slightly towards medial line proximally curves away frommedial line distally ( g 7L) Subterminal segment widest at base tapering sharplyinwards at 04 of length forms narrow process supporting terminal segment

Variation mdash All individuals are characteristically dark orange to red witha silver-blue sheen to the carapace while the chelipeds vary in colour frombright orange-red to a lighter yellow-orange All individuals are characterized byhighly vaulted carapaces and downwardly projecting frontal lobes The postfrontalcrest which is most pronounced laterally (from directly above the orbits to theanterolateral margin) and incomplete medially is often more distinct in the smaller

POTAMONAUTES LIVIDUS NOV 157

individuals Chelipeds are not always typically arched enclosing a large ovoidspace as in the holotype Chelipeds of smaller individuals although in ated areless arched and often tight closing with the small cutting teeth more obviousChelipeds of females and small males in particular from the Mdibi and Universityof Zululand localities have propodi that are relatively high with in ated palmsand relatively short tightly closing chelae which project slightly downwardsHeterochely has been demonstrated in most Potamonautes-species occurring inSouth Africa (Siegfried 1972 Raubenheimer 1986 Stewart et al 1995 Stewart1997a b Stewart amp Cook 1998 Daniels et al 1998a Gouws et al 2000) Withinthe species 76 of the specimens were right-handed with 11 being left-handedand 13 being of equal or subequal (differing by less than one millimeter) sizeOf the males 79 were right-handed 8 left-handed and 13 equal or subequalFemales had 74 right-handedness 13 left-handedness and in 13 of caseschelipeds were equal or subequal The abdomen of mature females completelyoverlaps the coxae of the pereopods The smallest mature female had a CL of167 mm with the largest immature female having a CL of 159 indicating that thepubertal moult occurs approximately between the 14 mm and 18 mm size classes

Remarks mdash Potamonautes lividus sp nov can readily be distinguished from theten other species in the genus Potamonautes known to occur within South AfricaPotamonautes warreni Calman 1918 P dentatus P parvispina and P unispinusall bear a singular spine or a series of teeth on the anterolateral margins whereasP lividus sp nov is smooth Potamonautes perlatus P sidneyi and P granularisare all larger crabs with in ated arched carapaces with complete distinct post-frontal crests and scabrosity or granulation of the anterior margins orbits epi-branchial corners or postfrontal crests Potamonautes lividus sp nov has smoothcarapace margins and a incomplete postfrontal crest The terminal segment ofgonopod 1 in P lividus sp nov is relatively short and triangular and curves awayfrom the medial line when viewed posteriorly while that of P sidneyi is relativelylonger more slender and more S-shaped The postfrontal crest of P sidneyi mayjoin the anterolateral margin at a relatively sharp angle and form a pronouncedepibranchial corner along the anterolateral margin The anterolateral margin inP lividus sp nov is more rounded and the epibranchial corners slope down to-wards the anks Potamonautes granularis is chocolate brown with orange tips tothe chelipeds Potamonautes brincki is a smaller crab with a smoother carapacethough also chocolate to reddish-brown in colour with a nely granulated antero-lateral margin which does not curve in over the carapace in the branchial region(Stewart 1997b) Potamonautes depressus and P clarus both have rounded epi-branchial corners and smooth carapaces though these are relatively shallow andhave attened dorsal surfaces Both are characterized by long slender limbs Pota-monautes depressus is brown to green-brown in colour while P clarus is brightorange in colour

158 G GOUWS B A STEWART amp P E REAVELL

A number of species from further a eld bear a super cial resemblance toP lividus sp nov particularly with regard to carapace morphology though in mostcases they can be readily distinguished Potamonautes pilosus Hilgendorf 1898 isknown from East Africa and is a small crab with a CWW of less than 25 mmSpecimens possess a weak postfrontal crest which along with the anterolateralmargin can be granulated (Hilgendorf 1898 Bott 1955) Potamonautes neumanniHilgendorf 1898 is known from East Africa and has a characteristically vaultedcarapace without a complete distinct postfrontal crest (Hilgendorf 1898 Bott1955) The postfrontal crest is more distinct in P lividus particularly laterally andthe exorbital teeth are sharper and more de ned in P lividus than in P neumanniThe terminal segment of gonopod 1 is longer and more slender in P neumannithan in P lividus and curves distinctly outwards The subterminal segment ofgonopod 1 is wider at its apex in P neumanni than in P lividus Additionally thecarapace of preserved specimens of P neumanni is typically grey in colour whileliving specimens are violet in colour with bright olive-green limbs and chelipeds(Hilgendorf 1898) Potamonautes ballayi acristatus Bott 1955 has an incompletepostfrontal crest only present above the orbits and small and blunt exorbital teethThe major chela although highly arched and the minor chela are long and moreslender than those of P lividus sp nov The terminal segment of gonopod 1 ofP granviki Colosi 1924 is curved towards the medial line when viewed posteriorly(Bott 1955) The chelae of both P berardi berardi Audouin 1826 and P b ignestiiParisi 1923 are relatively short and high with stout downward-projecting ngersThe anterior margin of the frontal lobe of P b berardi shows a distinct invaginationand the anterolateral margin appears sharp and less rounded than in P lividus spnov while the postfrontal crest of P b ignestii is complete and has a fairly longmedial groove Potamonautes emini emini Hilgendorf 1892 are generally smallcrabs with a less in ated carapace and short stout chelipeds The subterminaland terminal segments of gonopod 1 are of more or less equal size (Bott 1955)Potamonautes e semilunaris Bott 1955 and P luashiensis Bott 1955 are alsosmall crabs (CWW lt 20 mm) with the postfrontal crest only visible laterally andin the case of P luashiensis the anterolateral margin and postfrontal crest mayshow granulation Potamonautes didieri Rathbun 1904 possesses a more completerounded postfrontal crest and shorter more stout chelipeds (Bott 1955)

ACKNOWLEDGEMENTS

Financial assistance was kindly provided by the World Wildlife Fund - SouthAfrica the Foundation for Research Development and the University of ZululandThe KwaZulu-Natal Nature Conservation Services provided accommodation and

POTAMONAUTES LIVIDUS NOV 159

logistic support Liz Hoenson Peter Cook Mike Coke and Tyrone Ridgway arethanked for assistance in the eld and Michelle van der Merwe is thanked foraiding in the photography and drafting of gures The authors wish to thank ananonymous reviewer for comments on the manuscript

REFERENCES

BARNARD K H 1935 Scienti c results of the Vernay-Lang Kalahari expedition March toSeptember 1930 Crustacea Ann Transvaal Mus 16 481-492

mdash mdash 1950 Descriptive catalogue of South African decapod Crustacea (crabs and shrimps) AnnSouth African Mus 38 1-837

BOCK W J 1986 Species concepts speciation and macroevolution In K IWATSUKIP H RAVEN amp W J BOCK (eds) Modern aspects of species 31-57 (University of TokyoPress Tokyo)

BOTT R 1955 Die Suumlsswasserkrabben von Afrika (Crust Decap) und ihre StammesgeschichteAnn Mus R Congo Belge (C Zool) 1 (33) 209-352 pls 1-30

BRUTON M N 1980 An outline of the ecology of the Mgobezeleni lake system at Sodwana withemphasis on the mangrove community In M N BRUTON amp K H COOPER (eds) Studieson the ecology of Maputaland 408-426 (Rhodes University Grahamstown)

CUMBERLIDGE N 1986 Ventilation of the branchial chambers in the amphibious West Africanfreshwater crab Sudanonautes (Convexonautes) aubryi monodi (Balss 1929) (BrachyuraPotamonautidae)Hydrobiol 134 53-65

mdash mdash 1991 The respiratory system of Globonautes macropus (Rathbun 1898) a terrestrialfreshwater crab from Liberia (GecarcinucoideaGecarcinucidae)Crustaceana 61 (1) 69-80

DANIELS S R B A STEWART amp M J GIBBONS 1998a Potamonautes granularis sp nov(Brachyura Potamonautidae) a new cryptic species of river crab from the Olifants Riversystem South Africa Crustaceana 71 (8) 885-903

mdash mdash mdash mdash amp mdash mdash 1998b Genetic and morphometric variation in the potamonautid river crabPotamonautes parvispina (Decapoda Potamonautidae) from two Western Cape rivers SouthAfrica Journ nat Hist London 32 1245-1258

mdash mdash mdash mdash amp mdash mdash 1999 Genetic structure among populations of Potamonautes perlatus(Decapoda Potamonautidae) from the Olifants River system in the Western Cape SouthAfrica Journ Zool London 249 (2) 137-142

DIacuteAZ H amp G RODRIacuteGUEZ 1977 The branchial chamber in terrestrial crabs a comparative studyBiol Bull Woods Hole 153 485-504

GOUWS G B A STEWART amp M COKE 2000 Evidence for a new species of river crab(Decapoda Brachyura Potamonautidae) from the Drakensberg South Africa Journ CrustBiol 20 (4) 743-758

GREENAWAY P amp H H TAYLOR 1976 Aerial gas exchange in Australian arid-zone crabParathelphusa transversa Von Martens Nature London 262 711-713

HILGENDORF F 1898 Die Land- und Suumlsswasser-Dekapoden Ostafrikas Die Thierwelt DeutschOst-Afrikas 4 (7) 1-37

LENZ H 1912 Afrikanische Crustaceen aus schwedischen Sammlungen Ark Zool 7 (29) 1-10MARKERT C L amp I FAULHABER 1965 Lactate dehydrogenase isozyme patterns of sh Journ

exp Zool 159 319-332MAYR E 1963 Animal species and evolution i-xiv 1-797 (Harvard University Press Cambridge

Massachusetts)mdash mdash 1970 Populations species and evolution i-xv 1-453 (Harvard University Press Cambridge

Massachusetts)

148 G GOUWS B A STEWART amp P E REAVELL

Fig 4 Comparisons of the regressions of (A) Log CH (carapace height) over Log CL (carapacelength) (B) Log ED (eye distance) over Log CL and (C) Log CWP (posterior carapace width) overLog CL between form A (Potamonautes lividus sp nov) and form B (P sidneyi Rathbun 1904) All

differences are signi cant (at the P lt 0005 level)

POTAMONAUTES LIVIDUS NOV 149

Fig 5 A-E form A (Potamonautes lividus sp nov composite of male holotype SAM A43540and unaccessioned material) A carapace outline B left mandibular palp anterior view C leftmandibular palp posterior view D left gonopod 1 anterior view and E left gonopod 1 posteriorview F-J form B (Potamonautes sidneyi Rathbun 1904 unaccessioned specimen) F carapaceoutline G left mandibular palp anterior view H left mandibular palp posterior view I left

gonopod 1 anterior view J left gonopod 1 posterior view

150 G GOUWS B A STEWART amp P E REAVELL

interference and ecological competition This would lead to a divergence of mor-phological and behavioural aspects of feeding reproduction and other ecologicalfeatures The different gonopod morphologies of the two forms may re ect this

The three form A populations clustered separately from the three P sidneyipopulations at a I -value of 0829 Stewart (1997a) calculated the separationI -value between P parvispina Stewart 1997 and P perlatus H Milne Edwards1837 to be 068 An I -value of 066 separated both P perlatus and P brinckiBott 1960 in the Western Cape (Stewart 1997b) and P unispinus Stewart ampCook 1998 and P sidneyi in Mpumalanga (Stewart amp Cook 1998) An I -valueof 0599 was obtained separating P clarus Gouws Stewart amp Coke 2000 andP depressus (Gouws et al 2000) The only species in the genus delineated using ahigher I -value was P granularis Daniels Stewart amp Gibbons 1998 which wasseparated from P perlatus in the Olifants River at a I -value of 088 (Danielset al 1998a 1999) Although slightly higher than most interspeci c values inthe genus the value obtained in this study nevertheless falls within the range (035to 085) speci ed by Thorpe (1982) to indicate congeneric species differencesAllopatric populations showing I -values of less than 085 are unlikely to beconspeci c (Thorpe amp Soleacute-Cava 1994) With the exception of two cases allpairwise comparisons between allopatric populations of the two forms yieldedI -values less than 085

Identity-values were high for comparisons within both the form A (0949 to0986) and P sidneyi (0994 to 0999) groups Intraspeci c I -values are generallyhigh in the genus Potamonautes and disjunct populations within a species tendto be genetically undifferentiated Intraspeci c I -values obtained in six studies(Stewart 1997a b Stewart amp Cook 1998 Daniels et al 1998b 1999) involvingsix Potamonautes species varied from 0902 to 1000 (D D 0000 to 0103)An intraspeci c I -value of 075 was obtained in a comparison of two groups ofP brincki populations across the Cape Peninsula and Cape Flats However thismost probably indicates a species difference and requires further investigation(Stewart 1997b) Given the high intraspeci c I -values characteristic of the genusand those obtained for comparisons within each form the I -value obtainedfor the comparison between the two forms most likely represents a speciesdifference

Bock (1986) also de ned a species as possessing a set of three distinctcharacteristics genetic unity reproductive unity and ecological unity Biochemicaldata provide support for compliance with the rst two criteria for both formsWhile no empirical evidence is as yet available con rming the third factor adegree of macro- and microhabitat segregation and thus ecological segregationis evident between the two forms Potamonautes sidneyi is widespread acrossthe province (Stewart et al 1995) while the other form appears to have a

POTAMONAUTES LIVIDUS NOV 151

more limited distribution in northeastern KwaZulu-Natal restricted to patches ofswamp forest with particular oral assemblages The swamp forests are oftencharacterized by Barringtonia racemosa Syzygium cordatum Ficus trichopodaHibiscus tiliaceus L Rauvola caffra Sond Voacanga thouarsii Roem amp SchultRaphia australis Oberm amp Strey and Podocarpus falcatus (Thunb) R Br exMirb with the fern Stenochlaena tenuifolia (Desv) T Moore often present in theunderstorey (Bruton 1980 Moll 1980) Within the swamp forests the sympatricpopulations appear to show a degree of microhabitat segregation Observationssuggest that P sidneyi has a closer association with water as individuals were nevercollected great distances away from seepage pools and channels owing throughthe forest Conversely individuals of the swamp-forest form were most oftencollected farther from water and their burrows were often among the vegetationObservations suggest that this form is more terrestrial Individuals were noticedto move to higher elevations when the water table rose through the hydromorphicpeat soil ooding their burrows and the surface and they were also more active oncloudy overcast days Evidence of terrestrial adaptation is most likely to be foundin the structure and histology of the organs and tissues involved in respirationfactors such as branchial chamber shape and volume gill structure and formulaand the structure and vascularization of the branchiostegite lining are knownto re ect changes brought upon by the constraints of the terrestrial environment(Greenaway amp Taylor 1976 Diacuteaz amp Rodriacuteguez 1977 Taylor amp Greenaway1979 Cumberlidge 1986 1991 Takeda et al 1996) Although the availabilityof material prohibited the investigation of this aspect future research may prove tobe fruitful and highlight a greater distinction between the two forms

Studies on terrestrial adaptation supplemented by behavioural data that couldillustrate microhabitat and ecological segregation would quantify further thedegree of differentiation between the two forms However two independent datasets biochemical and morphological present strong evidence for the speci c statusof the swamp-forest form

TAXONOMY

Potamonautes lividus sp nov ( gs 6-7)

Material examined mdash Holotype South African Museum (SAM) A43540 one male CL D255 mm Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws andL Hoenson Allotype SAM A43541 one female CL D 245 mm Ficus and Barringtonia swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S 32plusmn2401800E)coll 27 January 1997 by B A Stewart G Gouws and L Hoenson Other material SAM A43542two males Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws

152 G GOUWS B A STEWART amp P E REAVELL

and L Hoenson SAM A43543 one female Lake Nhlabane north of Richards Bay (28plusmn3800500S32plusmn1601700E) coll 27 April 1993 by the University of Zululand Zoology Department SAMA43544 three males one female Mdibi swamp forest along Mdibi stream 8 km north of RichardsBay (28plusmn4202400S 32plusmn0902600E) coll 26 January 1997 by B A Stewart P A Cook M CokeP E Reavell G Gouws and L Hoenson SAM A43545 one male one female Syzygium forestUniversity of Zululand campus (28plusmn5102500S 31plusmn5100200E) coll 24 January 1997 by B A StewartP A Cook P E Reavell G Gouws and L Hoenson SAM A43546 two males two femalesUniversity of Zululand stream owing through campus (28plusmn550S 31plusmn410E) coll 10 September 1995by P E Reavell SAM A41313 one male one female swamp forest Empangeni (28plusmn5102500S31plusmn5100200E) coll 2 August 1994 by M Coke SAM A41155 one male University of ZululandSyzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S 31plusmn450E) coll 10 December1988 by P E Reavell SAM A41153 three males smaller holes in hydromorphic soil Syzygiumcordatum swamp forest University of Zululand (28plusmn450S 31plusmn450E) coll 20 March 1994 byP E Reavell SAM A41156 one female Syzygium cordatum swamp forest University of Zululand(28plusmn450S 31plusmn450E) coll 18 May 1992 by P E Reavell SAM A41154 one male one femaleUniversity of Zululand Syzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S31plusmn450E) coll 10 May 1990 by P E Reavell SAM A43547 two males one female swamp forestUniversity of Zululand (28plusmn450S 31plusmn450E) coll 1 April 1994 by P E Reavell SAM A43548one male one female Syzygium and Bridelia dominated swamp forest University of Zululand(28plusmn5102500S 31plusmn5100200E) coll 7 October 1996 by P E Reavell SAM A43549 one female Mdibiswamp forest Lake Msingazi catchment area north of Richards Bay (28plusmn420S 32plusmn090E) coll5 December 1996 by P E Reavell Albany Museum mdash GEN910 one female Mpolozi swampsMapelane (28plusmn2601300S 32plusmn2402500E) coll 13 February 1991 Albany Museum mdash GEN965 twomales ve females NrsquoKoninga Valley Richards Bay (28plusmn450S 32plusmn030E) coll 7 April 1988

Other material mdash The following specimens included in the collections of the South AfricanMuseum warrant further investigation as although they bear some resemblance to the speciesdescribed below their identi cation is uncertain SAM A41276 one male one female Mbonenidam Mkuze Game Reserve (27plusmn3705700S 32plusmn1504500E) coll 28 October 1994 by M Coke SAMA41299 two males Nxwala stream Mkuze Game Reserve (27plusmn4302300S 32plusmn1601000E) coll 10November 1994 by O Bourquin SAM A41277 one male Rainpool south of entrance False BayPark (28plusmn0000100S 32plusmn2102100E) coll 26 October 1994 by M Coke SAM A41300 two malesKangela rainpoolN2 near Mtubatuba (28plusmn2200000S 32plusmn1103600E) coll 25 October 1994 by M Cokeand SAM A41211 one male Ntambanana (Ntrabanana) Zululand coll by H H Curson

Type locality mdash South Africa KwaZulu-Natal Barringtonia and Ficus swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S32plusmn2401800E)

Distribution mdash At present known only from the swamp forests (characterizedby Barringtonia racemosa Syzygium cordatum and Ficus trichopoda vegetationand spongy hydromorphic peat-soil) in the vicinity of Richards Bay Empangeniand the Mapelane Nature Reserve It is probable that the distribution of the speciesmay extend into low-lying areas to the east of the Drakensberg escarpment in theprovince of Mpumalanga and into Mozambique

Etymology mdash From the Latin ldquolividusrdquo meaning ldquobluerdquo or ldquolight bluerdquoreferring to the characteristic silver-blue sheen of the carapace The epitheton isan adjective agreeing in gender with the (masculine) generic name

POTAMONAUTES LIVIDUS NOV 153

Fig 6 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A wholeanimal dorsal aspect B whole animal ventral aspect C cephalothorax frontal aspect

Diagnosis mdash Carapace distinctly vaulted and relatively narrow posteriorlyEpibranchial teeth absent and anterolateral margin of the carapace smooth Post-frontal crest indistinct medially with frontal lobe projecting downwards Cara-pace characteristically orange to red with silver-blue sheen Chelipeds and limbs

154 G GOUWS B A STEWART amp P E REAVELL

bright orange to red with lighter cheliped and dactyl tips Chela in ated and highlyarched

Description of male holotype mdash Size Measurements of the holotype and theranges of other specimens are given in table IV

Carapace ( gs 6A C 7A) Carapace and limbs characteristically orange tored with the carapace possessing a silver-blue sheen when alive Preserved spec-imens (70 ethanol) appear less orange and the carapace retains a blue-greycolour Cephalothorax ovoid distinctly vaulted branchial region highly convex( g 6A C) maximum height and width at anterior third (ratio CHCL D 065CWWCL D 145) Anterior margin straight Urogastric grooves moderately wellde ned Cardiac grooves shallow and poorly de ned Carapace otherwise smoothPostfrontal crest smooth curves forward medially Postfrontal crest diminishesabove inner orbit margins though well de ned immediately lateral to forked mid-point groove by means of two indentations anterior to crest indicating epigas-tric lobes Exorbital teeth moderately sharp but small Epibranchial teeth ab-sent Anterolateral margin posterior to postfrontal crest smooth margin curvingin over carapace in branchial region though indistinctly Each ank has a longitu-dinal groove dividing the subhepatic from the pterygostomial region with verticalgroove running from longitudinal groove joining anterolateral margin between ex-orbital tooth and postfrontal crest

Sternites ( gs 6B 7B) Sternites 1 and 2 fused no suture visible First suture(sternal groove) between sternites 2 and 3 complete Second sternal groove

TABLE IVPotamonautes lividus sp nov wet weight (in g) and measurements (in mm) for the male holotype

and ranges for other individuals examined (maximum of 77 males and 70 females)

Variable Abbreviation Holotype Males Females

Wet weight WW 242 05-214 07-183Carapace length CL 255 84-247 89-276Carapace widest width CWW 370 114-360 118-373Carapace posterior width CWP 281 90-269 86-306Distance between postfrontal crest

and anterior margin PFCD 43 12-222 15-46Distance between orbits ED 114 42-119 43-123Distance between exorbital teeth CWA 259 96-254 96-262Carapace height CH 165 48-171 50-162Width of sixth abdominal segment AW6 75 28-74 31-240Major cheliped propodus length MCPL 427 71-402 76-291Major cheliped propodus height MCPH 198 28-189 28-142Pereopod 2 merus length P2ML 189 50-181 51-171Pereopod 2 merus width P2MW 58 19-56 18-59

POTAMONAUTES LIVIDUS NOV 155

Fig 7 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A carapaceoutline B thoracic sternum C right cheliped dactylus and propodus D left cheliped dactylusand propodus E left third maxilliped F left mandible and mandibular palp posterior view G leftmandibular palp posterior view H left mandibular palp anterior view I left gonopod 1 anteriorview J terminal segment left gonopod 1 anterior view K left gonopod 1 posterior view L leftgonopod 2 anterior view Scale lines represent 1 mm except for A-D where they represent 10 mm

156 G GOUWS B A STEWART amp P E REAVELL

between sternites 3 and 4 complete laterally becoming shallower mediallysloping sharply towards abdominopelvic region

Third maxillipeds ( gs 6C 7E) Filling entire buccal frame except for ovalefferent respiratory openings short agellum present on exopods ischium smoothwith moderately deep vertical groove

Mandibular palp ( g 7F G H) Mandibular palp with two segments terminalsegment undivided with a dense tuft of setae on posterior surface of angeof terminal segment Margins generally hirsute Subterminal segment slightlyenlarged distally

Chelipeds and walking legs ( gs 6A 7C D) Chelipeds markedly unequaldactylus of right cheliped strongly arched 163 times length of dactylus of leftcheliped Both dactyli armed with up to 20 cutting teeth three to four of whichare slightly larger and more prominent Propodus of right cheliped markedlyin ated 168 times longer and 20 times wider than that of left cheliped Pollexpossesses 20 cutting teeth four to ve of which are more prominent Carpi ofboth chelipeds possess one prominent and three rudimentary teeth Margins ofmeri granulose small blunt spine on anterior surface no spine on anterior-inferiormargin Pereopods generally slender (pereopod 2 merus length width D 328 andpereopod 5 merus lengthwidth D 271) P3 longest P5 shortest ventral marginsof propodi and meri smooth dorsal margin with ne sharp bristles dactyli endingin sharp points with margins bearing a series of sharp spinelike bristles

Pleon ( gs 6B 7B) First ve segments broad and short last two segmentslonger terminal segment rounded at distal end

Pleopods ( g 7I J K) Pleopod 1 (gonopod 1) terminal segment short 025times length of subterminal segment terminal segment curves away from mid-line when viewed posteriorly widest at base ending in pointed tip Subterminalsegment of pleopod 1 tapers distally inner lateral margin slightly irregular outerlateral margin straighter both margins hirsute Posterior surface with twisting lon-gitudinal groove extending length of subterminal and terminal segment Groovenot visible on anterior surface Posterior surface and margins of groove hirsutePleopod 2 (gonopod 2) terminal segment lament-like 05 the length of subter-minal segment curving slightly towards medial line proximally curves away frommedial line distally ( g 7L) Subterminal segment widest at base tapering sharplyinwards at 04 of length forms narrow process supporting terminal segment

Variation mdash All individuals are characteristically dark orange to red witha silver-blue sheen to the carapace while the chelipeds vary in colour frombright orange-red to a lighter yellow-orange All individuals are characterized byhighly vaulted carapaces and downwardly projecting frontal lobes The postfrontalcrest which is most pronounced laterally (from directly above the orbits to theanterolateral margin) and incomplete medially is often more distinct in the smaller

POTAMONAUTES LIVIDUS NOV 157

individuals Chelipeds are not always typically arched enclosing a large ovoidspace as in the holotype Chelipeds of smaller individuals although in ated areless arched and often tight closing with the small cutting teeth more obviousChelipeds of females and small males in particular from the Mdibi and Universityof Zululand localities have propodi that are relatively high with in ated palmsand relatively short tightly closing chelae which project slightly downwardsHeterochely has been demonstrated in most Potamonautes-species occurring inSouth Africa (Siegfried 1972 Raubenheimer 1986 Stewart et al 1995 Stewart1997a b Stewart amp Cook 1998 Daniels et al 1998a Gouws et al 2000) Withinthe species 76 of the specimens were right-handed with 11 being left-handedand 13 being of equal or subequal (differing by less than one millimeter) sizeOf the males 79 were right-handed 8 left-handed and 13 equal or subequalFemales had 74 right-handedness 13 left-handedness and in 13 of caseschelipeds were equal or subequal The abdomen of mature females completelyoverlaps the coxae of the pereopods The smallest mature female had a CL of167 mm with the largest immature female having a CL of 159 indicating that thepubertal moult occurs approximately between the 14 mm and 18 mm size classes

Remarks mdash Potamonautes lividus sp nov can readily be distinguished from theten other species in the genus Potamonautes known to occur within South AfricaPotamonautes warreni Calman 1918 P dentatus P parvispina and P unispinusall bear a singular spine or a series of teeth on the anterolateral margins whereasP lividus sp nov is smooth Potamonautes perlatus P sidneyi and P granularisare all larger crabs with in ated arched carapaces with complete distinct post-frontal crests and scabrosity or granulation of the anterior margins orbits epi-branchial corners or postfrontal crests Potamonautes lividus sp nov has smoothcarapace margins and a incomplete postfrontal crest The terminal segment ofgonopod 1 in P lividus sp nov is relatively short and triangular and curves awayfrom the medial line when viewed posteriorly while that of P sidneyi is relativelylonger more slender and more S-shaped The postfrontal crest of P sidneyi mayjoin the anterolateral margin at a relatively sharp angle and form a pronouncedepibranchial corner along the anterolateral margin The anterolateral margin inP lividus sp nov is more rounded and the epibranchial corners slope down to-wards the anks Potamonautes granularis is chocolate brown with orange tips tothe chelipeds Potamonautes brincki is a smaller crab with a smoother carapacethough also chocolate to reddish-brown in colour with a nely granulated antero-lateral margin which does not curve in over the carapace in the branchial region(Stewart 1997b) Potamonautes depressus and P clarus both have rounded epi-branchial corners and smooth carapaces though these are relatively shallow andhave attened dorsal surfaces Both are characterized by long slender limbs Pota-monautes depressus is brown to green-brown in colour while P clarus is brightorange in colour

158 G GOUWS B A STEWART amp P E REAVELL

A number of species from further a eld bear a super cial resemblance toP lividus sp nov particularly with regard to carapace morphology though in mostcases they can be readily distinguished Potamonautes pilosus Hilgendorf 1898 isknown from East Africa and is a small crab with a CWW of less than 25 mmSpecimens possess a weak postfrontal crest which along with the anterolateralmargin can be granulated (Hilgendorf 1898 Bott 1955) Potamonautes neumanniHilgendorf 1898 is known from East Africa and has a characteristically vaultedcarapace without a complete distinct postfrontal crest (Hilgendorf 1898 Bott1955) The postfrontal crest is more distinct in P lividus particularly laterally andthe exorbital teeth are sharper and more de ned in P lividus than in P neumanniThe terminal segment of gonopod 1 is longer and more slender in P neumannithan in P lividus and curves distinctly outwards The subterminal segment ofgonopod 1 is wider at its apex in P neumanni than in P lividus Additionally thecarapace of preserved specimens of P neumanni is typically grey in colour whileliving specimens are violet in colour with bright olive-green limbs and chelipeds(Hilgendorf 1898) Potamonautes ballayi acristatus Bott 1955 has an incompletepostfrontal crest only present above the orbits and small and blunt exorbital teethThe major chela although highly arched and the minor chela are long and moreslender than those of P lividus sp nov The terminal segment of gonopod 1 ofP granviki Colosi 1924 is curved towards the medial line when viewed posteriorly(Bott 1955) The chelae of both P berardi berardi Audouin 1826 and P b ignestiiParisi 1923 are relatively short and high with stout downward-projecting ngersThe anterior margin of the frontal lobe of P b berardi shows a distinct invaginationand the anterolateral margin appears sharp and less rounded than in P lividus spnov while the postfrontal crest of P b ignestii is complete and has a fairly longmedial groove Potamonautes emini emini Hilgendorf 1892 are generally smallcrabs with a less in ated carapace and short stout chelipeds The subterminaland terminal segments of gonopod 1 are of more or less equal size (Bott 1955)Potamonautes e semilunaris Bott 1955 and P luashiensis Bott 1955 are alsosmall crabs (CWW lt 20 mm) with the postfrontal crest only visible laterally andin the case of P luashiensis the anterolateral margin and postfrontal crest mayshow granulation Potamonautes didieri Rathbun 1904 possesses a more completerounded postfrontal crest and shorter more stout chelipeds (Bott 1955)

ACKNOWLEDGEMENTS

Financial assistance was kindly provided by the World Wildlife Fund - SouthAfrica the Foundation for Research Development and the University of ZululandThe KwaZulu-Natal Nature Conservation Services provided accommodation and

POTAMONAUTES LIVIDUS NOV 159

logistic support Liz Hoenson Peter Cook Mike Coke and Tyrone Ridgway arethanked for assistance in the eld and Michelle van der Merwe is thanked foraiding in the photography and drafting of gures The authors wish to thank ananonymous reviewer for comments on the manuscript

REFERENCES

BARNARD K H 1935 Scienti c results of the Vernay-Lang Kalahari expedition March toSeptember 1930 Crustacea Ann Transvaal Mus 16 481-492

mdash mdash 1950 Descriptive catalogue of South African decapod Crustacea (crabs and shrimps) AnnSouth African Mus 38 1-837

BOCK W J 1986 Species concepts speciation and macroevolution In K IWATSUKIP H RAVEN amp W J BOCK (eds) Modern aspects of species 31-57 (University of TokyoPress Tokyo)

BOTT R 1955 Die Suumlsswasserkrabben von Afrika (Crust Decap) und ihre StammesgeschichteAnn Mus R Congo Belge (C Zool) 1 (33) 209-352 pls 1-30

BRUTON M N 1980 An outline of the ecology of the Mgobezeleni lake system at Sodwana withemphasis on the mangrove community In M N BRUTON amp K H COOPER (eds) Studieson the ecology of Maputaland 408-426 (Rhodes University Grahamstown)

CUMBERLIDGE N 1986 Ventilation of the branchial chambers in the amphibious West Africanfreshwater crab Sudanonautes (Convexonautes) aubryi monodi (Balss 1929) (BrachyuraPotamonautidae)Hydrobiol 134 53-65

mdash mdash 1991 The respiratory system of Globonautes macropus (Rathbun 1898) a terrestrialfreshwater crab from Liberia (GecarcinucoideaGecarcinucidae)Crustaceana 61 (1) 69-80

DANIELS S R B A STEWART amp M J GIBBONS 1998a Potamonautes granularis sp nov(Brachyura Potamonautidae) a new cryptic species of river crab from the Olifants Riversystem South Africa Crustaceana 71 (8) 885-903

mdash mdash mdash mdash amp mdash mdash 1998b Genetic and morphometric variation in the potamonautid river crabPotamonautes parvispina (Decapoda Potamonautidae) from two Western Cape rivers SouthAfrica Journ nat Hist London 32 1245-1258

mdash mdash mdash mdash amp mdash mdash 1999 Genetic structure among populations of Potamonautes perlatus(Decapoda Potamonautidae) from the Olifants River system in the Western Cape SouthAfrica Journ Zool London 249 (2) 137-142

DIacuteAZ H amp G RODRIacuteGUEZ 1977 The branchial chamber in terrestrial crabs a comparative studyBiol Bull Woods Hole 153 485-504

GOUWS G B A STEWART amp M COKE 2000 Evidence for a new species of river crab(Decapoda Brachyura Potamonautidae) from the Drakensberg South Africa Journ CrustBiol 20 (4) 743-758

GREENAWAY P amp H H TAYLOR 1976 Aerial gas exchange in Australian arid-zone crabParathelphusa transversa Von Martens Nature London 262 711-713

HILGENDORF F 1898 Die Land- und Suumlsswasser-Dekapoden Ostafrikas Die Thierwelt DeutschOst-Afrikas 4 (7) 1-37

LENZ H 1912 Afrikanische Crustaceen aus schwedischen Sammlungen Ark Zool 7 (29) 1-10MARKERT C L amp I FAULHABER 1965 Lactate dehydrogenase isozyme patterns of sh Journ

exp Zool 159 319-332MAYR E 1963 Animal species and evolution i-xiv 1-797 (Harvard University Press Cambridge

Massachusetts)mdash mdash 1970 Populations species and evolution i-xv 1-453 (Harvard University Press Cambridge

Massachusetts)

POTAMONAUTES LIVIDUS NOV 149

Fig 5 A-E form A (Potamonautes lividus sp nov composite of male holotype SAM A43540and unaccessioned material) A carapace outline B left mandibular palp anterior view C leftmandibular palp posterior view D left gonopod 1 anterior view and E left gonopod 1 posteriorview F-J form B (Potamonautes sidneyi Rathbun 1904 unaccessioned specimen) F carapaceoutline G left mandibular palp anterior view H left mandibular palp posterior view I left

gonopod 1 anterior view J left gonopod 1 posterior view

150 G GOUWS B A STEWART amp P E REAVELL

interference and ecological competition This would lead to a divergence of mor-phological and behavioural aspects of feeding reproduction and other ecologicalfeatures The different gonopod morphologies of the two forms may re ect this

The three form A populations clustered separately from the three P sidneyipopulations at a I -value of 0829 Stewart (1997a) calculated the separationI -value between P parvispina Stewart 1997 and P perlatus H Milne Edwards1837 to be 068 An I -value of 066 separated both P perlatus and P brinckiBott 1960 in the Western Cape (Stewart 1997b) and P unispinus Stewart ampCook 1998 and P sidneyi in Mpumalanga (Stewart amp Cook 1998) An I -valueof 0599 was obtained separating P clarus Gouws Stewart amp Coke 2000 andP depressus (Gouws et al 2000) The only species in the genus delineated using ahigher I -value was P granularis Daniels Stewart amp Gibbons 1998 which wasseparated from P perlatus in the Olifants River at a I -value of 088 (Danielset al 1998a 1999) Although slightly higher than most interspeci c values inthe genus the value obtained in this study nevertheless falls within the range (035to 085) speci ed by Thorpe (1982) to indicate congeneric species differencesAllopatric populations showing I -values of less than 085 are unlikely to beconspeci c (Thorpe amp Soleacute-Cava 1994) With the exception of two cases allpairwise comparisons between allopatric populations of the two forms yieldedI -values less than 085

Identity-values were high for comparisons within both the form A (0949 to0986) and P sidneyi (0994 to 0999) groups Intraspeci c I -values are generallyhigh in the genus Potamonautes and disjunct populations within a species tendto be genetically undifferentiated Intraspeci c I -values obtained in six studies(Stewart 1997a b Stewart amp Cook 1998 Daniels et al 1998b 1999) involvingsix Potamonautes species varied from 0902 to 1000 (D D 0000 to 0103)An intraspeci c I -value of 075 was obtained in a comparison of two groups ofP brincki populations across the Cape Peninsula and Cape Flats However thismost probably indicates a species difference and requires further investigation(Stewart 1997b) Given the high intraspeci c I -values characteristic of the genusand those obtained for comparisons within each form the I -value obtainedfor the comparison between the two forms most likely represents a speciesdifference

Bock (1986) also de ned a species as possessing a set of three distinctcharacteristics genetic unity reproductive unity and ecological unity Biochemicaldata provide support for compliance with the rst two criteria for both formsWhile no empirical evidence is as yet available con rming the third factor adegree of macro- and microhabitat segregation and thus ecological segregationis evident between the two forms Potamonautes sidneyi is widespread acrossthe province (Stewart et al 1995) while the other form appears to have a

POTAMONAUTES LIVIDUS NOV 151

more limited distribution in northeastern KwaZulu-Natal restricted to patches ofswamp forest with particular oral assemblages The swamp forests are oftencharacterized by Barringtonia racemosa Syzygium cordatum Ficus trichopodaHibiscus tiliaceus L Rauvola caffra Sond Voacanga thouarsii Roem amp SchultRaphia australis Oberm amp Strey and Podocarpus falcatus (Thunb) R Br exMirb with the fern Stenochlaena tenuifolia (Desv) T Moore often present in theunderstorey (Bruton 1980 Moll 1980) Within the swamp forests the sympatricpopulations appear to show a degree of microhabitat segregation Observationssuggest that P sidneyi has a closer association with water as individuals were nevercollected great distances away from seepage pools and channels owing throughthe forest Conversely individuals of the swamp-forest form were most oftencollected farther from water and their burrows were often among the vegetationObservations suggest that this form is more terrestrial Individuals were noticedto move to higher elevations when the water table rose through the hydromorphicpeat soil ooding their burrows and the surface and they were also more active oncloudy overcast days Evidence of terrestrial adaptation is most likely to be foundin the structure and histology of the organs and tissues involved in respirationfactors such as branchial chamber shape and volume gill structure and formulaand the structure and vascularization of the branchiostegite lining are knownto re ect changes brought upon by the constraints of the terrestrial environment(Greenaway amp Taylor 1976 Diacuteaz amp Rodriacuteguez 1977 Taylor amp Greenaway1979 Cumberlidge 1986 1991 Takeda et al 1996) Although the availabilityof material prohibited the investigation of this aspect future research may prove tobe fruitful and highlight a greater distinction between the two forms

Studies on terrestrial adaptation supplemented by behavioural data that couldillustrate microhabitat and ecological segregation would quantify further thedegree of differentiation between the two forms However two independent datasets biochemical and morphological present strong evidence for the speci c statusof the swamp-forest form

TAXONOMY

Potamonautes lividus sp nov ( gs 6-7)

Material examined mdash Holotype South African Museum (SAM) A43540 one male CL D255 mm Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws andL Hoenson Allotype SAM A43541 one female CL D 245 mm Ficus and Barringtonia swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S 32plusmn2401800E)coll 27 January 1997 by B A Stewart G Gouws and L Hoenson Other material SAM A43542two males Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws

152 G GOUWS B A STEWART amp P E REAVELL

and L Hoenson SAM A43543 one female Lake Nhlabane north of Richards Bay (28plusmn3800500S32plusmn1601700E) coll 27 April 1993 by the University of Zululand Zoology Department SAMA43544 three males one female Mdibi swamp forest along Mdibi stream 8 km north of RichardsBay (28plusmn4202400S 32plusmn0902600E) coll 26 January 1997 by B A Stewart P A Cook M CokeP E Reavell G Gouws and L Hoenson SAM A43545 one male one female Syzygium forestUniversity of Zululand campus (28plusmn5102500S 31plusmn5100200E) coll 24 January 1997 by B A StewartP A Cook P E Reavell G Gouws and L Hoenson SAM A43546 two males two femalesUniversity of Zululand stream owing through campus (28plusmn550S 31plusmn410E) coll 10 September 1995by P E Reavell SAM A41313 one male one female swamp forest Empangeni (28plusmn5102500S31plusmn5100200E) coll 2 August 1994 by M Coke SAM A41155 one male University of ZululandSyzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S 31plusmn450E) coll 10 December1988 by P E Reavell SAM A41153 three males smaller holes in hydromorphic soil Syzygiumcordatum swamp forest University of Zululand (28plusmn450S 31plusmn450E) coll 20 March 1994 byP E Reavell SAM A41156 one female Syzygium cordatum swamp forest University of Zululand(28plusmn450S 31plusmn450E) coll 18 May 1992 by P E Reavell SAM A41154 one male one femaleUniversity of Zululand Syzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S31plusmn450E) coll 10 May 1990 by P E Reavell SAM A43547 two males one female swamp forestUniversity of Zululand (28plusmn450S 31plusmn450E) coll 1 April 1994 by P E Reavell SAM A43548one male one female Syzygium and Bridelia dominated swamp forest University of Zululand(28plusmn5102500S 31plusmn5100200E) coll 7 October 1996 by P E Reavell SAM A43549 one female Mdibiswamp forest Lake Msingazi catchment area north of Richards Bay (28plusmn420S 32plusmn090E) coll5 December 1996 by P E Reavell Albany Museum mdash GEN910 one female Mpolozi swampsMapelane (28plusmn2601300S 32plusmn2402500E) coll 13 February 1991 Albany Museum mdash GEN965 twomales ve females NrsquoKoninga Valley Richards Bay (28plusmn450S 32plusmn030E) coll 7 April 1988

Other material mdash The following specimens included in the collections of the South AfricanMuseum warrant further investigation as although they bear some resemblance to the speciesdescribed below their identi cation is uncertain SAM A41276 one male one female Mbonenidam Mkuze Game Reserve (27plusmn3705700S 32plusmn1504500E) coll 28 October 1994 by M Coke SAMA41299 two males Nxwala stream Mkuze Game Reserve (27plusmn4302300S 32plusmn1601000E) coll 10November 1994 by O Bourquin SAM A41277 one male Rainpool south of entrance False BayPark (28plusmn0000100S 32plusmn2102100E) coll 26 October 1994 by M Coke SAM A41300 two malesKangela rainpoolN2 near Mtubatuba (28plusmn2200000S 32plusmn1103600E) coll 25 October 1994 by M Cokeand SAM A41211 one male Ntambanana (Ntrabanana) Zululand coll by H H Curson

Type locality mdash South Africa KwaZulu-Natal Barringtonia and Ficus swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S32plusmn2401800E)

Distribution mdash At present known only from the swamp forests (characterizedby Barringtonia racemosa Syzygium cordatum and Ficus trichopoda vegetationand spongy hydromorphic peat-soil) in the vicinity of Richards Bay Empangeniand the Mapelane Nature Reserve It is probable that the distribution of the speciesmay extend into low-lying areas to the east of the Drakensberg escarpment in theprovince of Mpumalanga and into Mozambique

Etymology mdash From the Latin ldquolividusrdquo meaning ldquobluerdquo or ldquolight bluerdquoreferring to the characteristic silver-blue sheen of the carapace The epitheton isan adjective agreeing in gender with the (masculine) generic name

POTAMONAUTES LIVIDUS NOV 153

Fig 6 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A wholeanimal dorsal aspect B whole animal ventral aspect C cephalothorax frontal aspect

Diagnosis mdash Carapace distinctly vaulted and relatively narrow posteriorlyEpibranchial teeth absent and anterolateral margin of the carapace smooth Post-frontal crest indistinct medially with frontal lobe projecting downwards Cara-pace characteristically orange to red with silver-blue sheen Chelipeds and limbs

154 G GOUWS B A STEWART amp P E REAVELL

bright orange to red with lighter cheliped and dactyl tips Chela in ated and highlyarched

Description of male holotype mdash Size Measurements of the holotype and theranges of other specimens are given in table IV

Carapace ( gs 6A C 7A) Carapace and limbs characteristically orange tored with the carapace possessing a silver-blue sheen when alive Preserved spec-imens (70 ethanol) appear less orange and the carapace retains a blue-greycolour Cephalothorax ovoid distinctly vaulted branchial region highly convex( g 6A C) maximum height and width at anterior third (ratio CHCL D 065CWWCL D 145) Anterior margin straight Urogastric grooves moderately wellde ned Cardiac grooves shallow and poorly de ned Carapace otherwise smoothPostfrontal crest smooth curves forward medially Postfrontal crest diminishesabove inner orbit margins though well de ned immediately lateral to forked mid-point groove by means of two indentations anterior to crest indicating epigas-tric lobes Exorbital teeth moderately sharp but small Epibranchial teeth ab-sent Anterolateral margin posterior to postfrontal crest smooth margin curvingin over carapace in branchial region though indistinctly Each ank has a longitu-dinal groove dividing the subhepatic from the pterygostomial region with verticalgroove running from longitudinal groove joining anterolateral margin between ex-orbital tooth and postfrontal crest

Sternites ( gs 6B 7B) Sternites 1 and 2 fused no suture visible First suture(sternal groove) between sternites 2 and 3 complete Second sternal groove

TABLE IVPotamonautes lividus sp nov wet weight (in g) and measurements (in mm) for the male holotype

and ranges for other individuals examined (maximum of 77 males and 70 females)

Variable Abbreviation Holotype Males Females

Wet weight WW 242 05-214 07-183Carapace length CL 255 84-247 89-276Carapace widest width CWW 370 114-360 118-373Carapace posterior width CWP 281 90-269 86-306Distance between postfrontal crest

and anterior margin PFCD 43 12-222 15-46Distance between orbits ED 114 42-119 43-123Distance between exorbital teeth CWA 259 96-254 96-262Carapace height CH 165 48-171 50-162Width of sixth abdominal segment AW6 75 28-74 31-240Major cheliped propodus length MCPL 427 71-402 76-291Major cheliped propodus height MCPH 198 28-189 28-142Pereopod 2 merus length P2ML 189 50-181 51-171Pereopod 2 merus width P2MW 58 19-56 18-59

POTAMONAUTES LIVIDUS NOV 155

Fig 7 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A carapaceoutline B thoracic sternum C right cheliped dactylus and propodus D left cheliped dactylusand propodus E left third maxilliped F left mandible and mandibular palp posterior view G leftmandibular palp posterior view H left mandibular palp anterior view I left gonopod 1 anteriorview J terminal segment left gonopod 1 anterior view K left gonopod 1 posterior view L leftgonopod 2 anterior view Scale lines represent 1 mm except for A-D where they represent 10 mm

156 G GOUWS B A STEWART amp P E REAVELL

between sternites 3 and 4 complete laterally becoming shallower mediallysloping sharply towards abdominopelvic region

Third maxillipeds ( gs 6C 7E) Filling entire buccal frame except for ovalefferent respiratory openings short agellum present on exopods ischium smoothwith moderately deep vertical groove

Mandibular palp ( g 7F G H) Mandibular palp with two segments terminalsegment undivided with a dense tuft of setae on posterior surface of angeof terminal segment Margins generally hirsute Subterminal segment slightlyenlarged distally

Chelipeds and walking legs ( gs 6A 7C D) Chelipeds markedly unequaldactylus of right cheliped strongly arched 163 times length of dactylus of leftcheliped Both dactyli armed with up to 20 cutting teeth three to four of whichare slightly larger and more prominent Propodus of right cheliped markedlyin ated 168 times longer and 20 times wider than that of left cheliped Pollexpossesses 20 cutting teeth four to ve of which are more prominent Carpi ofboth chelipeds possess one prominent and three rudimentary teeth Margins ofmeri granulose small blunt spine on anterior surface no spine on anterior-inferiormargin Pereopods generally slender (pereopod 2 merus length width D 328 andpereopod 5 merus lengthwidth D 271) P3 longest P5 shortest ventral marginsof propodi and meri smooth dorsal margin with ne sharp bristles dactyli endingin sharp points with margins bearing a series of sharp spinelike bristles

Pleon ( gs 6B 7B) First ve segments broad and short last two segmentslonger terminal segment rounded at distal end

Pleopods ( g 7I J K) Pleopod 1 (gonopod 1) terminal segment short 025times length of subterminal segment terminal segment curves away from mid-line when viewed posteriorly widest at base ending in pointed tip Subterminalsegment of pleopod 1 tapers distally inner lateral margin slightly irregular outerlateral margin straighter both margins hirsute Posterior surface with twisting lon-gitudinal groove extending length of subterminal and terminal segment Groovenot visible on anterior surface Posterior surface and margins of groove hirsutePleopod 2 (gonopod 2) terminal segment lament-like 05 the length of subter-minal segment curving slightly towards medial line proximally curves away frommedial line distally ( g 7L) Subterminal segment widest at base tapering sharplyinwards at 04 of length forms narrow process supporting terminal segment

Variation mdash All individuals are characteristically dark orange to red witha silver-blue sheen to the carapace while the chelipeds vary in colour frombright orange-red to a lighter yellow-orange All individuals are characterized byhighly vaulted carapaces and downwardly projecting frontal lobes The postfrontalcrest which is most pronounced laterally (from directly above the orbits to theanterolateral margin) and incomplete medially is often more distinct in the smaller

POTAMONAUTES LIVIDUS NOV 157

individuals Chelipeds are not always typically arched enclosing a large ovoidspace as in the holotype Chelipeds of smaller individuals although in ated areless arched and often tight closing with the small cutting teeth more obviousChelipeds of females and small males in particular from the Mdibi and Universityof Zululand localities have propodi that are relatively high with in ated palmsand relatively short tightly closing chelae which project slightly downwardsHeterochely has been demonstrated in most Potamonautes-species occurring inSouth Africa (Siegfried 1972 Raubenheimer 1986 Stewart et al 1995 Stewart1997a b Stewart amp Cook 1998 Daniels et al 1998a Gouws et al 2000) Withinthe species 76 of the specimens were right-handed with 11 being left-handedand 13 being of equal or subequal (differing by less than one millimeter) sizeOf the males 79 were right-handed 8 left-handed and 13 equal or subequalFemales had 74 right-handedness 13 left-handedness and in 13 of caseschelipeds were equal or subequal The abdomen of mature females completelyoverlaps the coxae of the pereopods The smallest mature female had a CL of167 mm with the largest immature female having a CL of 159 indicating that thepubertal moult occurs approximately between the 14 mm and 18 mm size classes

Remarks mdash Potamonautes lividus sp nov can readily be distinguished from theten other species in the genus Potamonautes known to occur within South AfricaPotamonautes warreni Calman 1918 P dentatus P parvispina and P unispinusall bear a singular spine or a series of teeth on the anterolateral margins whereasP lividus sp nov is smooth Potamonautes perlatus P sidneyi and P granularisare all larger crabs with in ated arched carapaces with complete distinct post-frontal crests and scabrosity or granulation of the anterior margins orbits epi-branchial corners or postfrontal crests Potamonautes lividus sp nov has smoothcarapace margins and a incomplete postfrontal crest The terminal segment ofgonopod 1 in P lividus sp nov is relatively short and triangular and curves awayfrom the medial line when viewed posteriorly while that of P sidneyi is relativelylonger more slender and more S-shaped The postfrontal crest of P sidneyi mayjoin the anterolateral margin at a relatively sharp angle and form a pronouncedepibranchial corner along the anterolateral margin The anterolateral margin inP lividus sp nov is more rounded and the epibranchial corners slope down to-wards the anks Potamonautes granularis is chocolate brown with orange tips tothe chelipeds Potamonautes brincki is a smaller crab with a smoother carapacethough also chocolate to reddish-brown in colour with a nely granulated antero-lateral margin which does not curve in over the carapace in the branchial region(Stewart 1997b) Potamonautes depressus and P clarus both have rounded epi-branchial corners and smooth carapaces though these are relatively shallow andhave attened dorsal surfaces Both are characterized by long slender limbs Pota-monautes depressus is brown to green-brown in colour while P clarus is brightorange in colour

158 G GOUWS B A STEWART amp P E REAVELL

A number of species from further a eld bear a super cial resemblance toP lividus sp nov particularly with regard to carapace morphology though in mostcases they can be readily distinguished Potamonautes pilosus Hilgendorf 1898 isknown from East Africa and is a small crab with a CWW of less than 25 mmSpecimens possess a weak postfrontal crest which along with the anterolateralmargin can be granulated (Hilgendorf 1898 Bott 1955) Potamonautes neumanniHilgendorf 1898 is known from East Africa and has a characteristically vaultedcarapace without a complete distinct postfrontal crest (Hilgendorf 1898 Bott1955) The postfrontal crest is more distinct in P lividus particularly laterally andthe exorbital teeth are sharper and more de ned in P lividus than in P neumanniThe terminal segment of gonopod 1 is longer and more slender in P neumannithan in P lividus and curves distinctly outwards The subterminal segment ofgonopod 1 is wider at its apex in P neumanni than in P lividus Additionally thecarapace of preserved specimens of P neumanni is typically grey in colour whileliving specimens are violet in colour with bright olive-green limbs and chelipeds(Hilgendorf 1898) Potamonautes ballayi acristatus Bott 1955 has an incompletepostfrontal crest only present above the orbits and small and blunt exorbital teethThe major chela although highly arched and the minor chela are long and moreslender than those of P lividus sp nov The terminal segment of gonopod 1 ofP granviki Colosi 1924 is curved towards the medial line when viewed posteriorly(Bott 1955) The chelae of both P berardi berardi Audouin 1826 and P b ignestiiParisi 1923 are relatively short and high with stout downward-projecting ngersThe anterior margin of the frontal lobe of P b berardi shows a distinct invaginationand the anterolateral margin appears sharp and less rounded than in P lividus spnov while the postfrontal crest of P b ignestii is complete and has a fairly longmedial groove Potamonautes emini emini Hilgendorf 1892 are generally smallcrabs with a less in ated carapace and short stout chelipeds The subterminaland terminal segments of gonopod 1 are of more or less equal size (Bott 1955)Potamonautes e semilunaris Bott 1955 and P luashiensis Bott 1955 are alsosmall crabs (CWW lt 20 mm) with the postfrontal crest only visible laterally andin the case of P luashiensis the anterolateral margin and postfrontal crest mayshow granulation Potamonautes didieri Rathbun 1904 possesses a more completerounded postfrontal crest and shorter more stout chelipeds (Bott 1955)

ACKNOWLEDGEMENTS

Financial assistance was kindly provided by the World Wildlife Fund - SouthAfrica the Foundation for Research Development and the University of ZululandThe KwaZulu-Natal Nature Conservation Services provided accommodation and

POTAMONAUTES LIVIDUS NOV 159

logistic support Liz Hoenson Peter Cook Mike Coke and Tyrone Ridgway arethanked for assistance in the eld and Michelle van der Merwe is thanked foraiding in the photography and drafting of gures The authors wish to thank ananonymous reviewer for comments on the manuscript

REFERENCES

BARNARD K H 1935 Scienti c results of the Vernay-Lang Kalahari expedition March toSeptember 1930 Crustacea Ann Transvaal Mus 16 481-492

mdash mdash 1950 Descriptive catalogue of South African decapod Crustacea (crabs and shrimps) AnnSouth African Mus 38 1-837

BOCK W J 1986 Species concepts speciation and macroevolution In K IWATSUKIP H RAVEN amp W J BOCK (eds) Modern aspects of species 31-57 (University of TokyoPress Tokyo)

BOTT R 1955 Die Suumlsswasserkrabben von Afrika (Crust Decap) und ihre StammesgeschichteAnn Mus R Congo Belge (C Zool) 1 (33) 209-352 pls 1-30

BRUTON M N 1980 An outline of the ecology of the Mgobezeleni lake system at Sodwana withemphasis on the mangrove community In M N BRUTON amp K H COOPER (eds) Studieson the ecology of Maputaland 408-426 (Rhodes University Grahamstown)

CUMBERLIDGE N 1986 Ventilation of the branchial chambers in the amphibious West Africanfreshwater crab Sudanonautes (Convexonautes) aubryi monodi (Balss 1929) (BrachyuraPotamonautidae)Hydrobiol 134 53-65

mdash mdash 1991 The respiratory system of Globonautes macropus (Rathbun 1898) a terrestrialfreshwater crab from Liberia (GecarcinucoideaGecarcinucidae)Crustaceana 61 (1) 69-80

DANIELS S R B A STEWART amp M J GIBBONS 1998a Potamonautes granularis sp nov(Brachyura Potamonautidae) a new cryptic species of river crab from the Olifants Riversystem South Africa Crustaceana 71 (8) 885-903

mdash mdash mdash mdash amp mdash mdash 1998b Genetic and morphometric variation in the potamonautid river crabPotamonautes parvispina (Decapoda Potamonautidae) from two Western Cape rivers SouthAfrica Journ nat Hist London 32 1245-1258

mdash mdash mdash mdash amp mdash mdash 1999 Genetic structure among populations of Potamonautes perlatus(Decapoda Potamonautidae) from the Olifants River system in the Western Cape SouthAfrica Journ Zool London 249 (2) 137-142

DIacuteAZ H amp G RODRIacuteGUEZ 1977 The branchial chamber in terrestrial crabs a comparative studyBiol Bull Woods Hole 153 485-504

GOUWS G B A STEWART amp M COKE 2000 Evidence for a new species of river crab(Decapoda Brachyura Potamonautidae) from the Drakensberg South Africa Journ CrustBiol 20 (4) 743-758

GREENAWAY P amp H H TAYLOR 1976 Aerial gas exchange in Australian arid-zone crabParathelphusa transversa Von Martens Nature London 262 711-713

HILGENDORF F 1898 Die Land- und Suumlsswasser-Dekapoden Ostafrikas Die Thierwelt DeutschOst-Afrikas 4 (7) 1-37

LENZ H 1912 Afrikanische Crustaceen aus schwedischen Sammlungen Ark Zool 7 (29) 1-10MARKERT C L amp I FAULHABER 1965 Lactate dehydrogenase isozyme patterns of sh Journ

exp Zool 159 319-332MAYR E 1963 Animal species and evolution i-xiv 1-797 (Harvard University Press Cambridge

Massachusetts)mdash mdash 1970 Populations species and evolution i-xv 1-453 (Harvard University Press Cambridge

Massachusetts)

150 G GOUWS B A STEWART amp P E REAVELL

interference and ecological competition This would lead to a divergence of mor-phological and behavioural aspects of feeding reproduction and other ecologicalfeatures The different gonopod morphologies of the two forms may re ect this

The three form A populations clustered separately from the three P sidneyipopulations at a I -value of 0829 Stewart (1997a) calculated the separationI -value between P parvispina Stewart 1997 and P perlatus H Milne Edwards1837 to be 068 An I -value of 066 separated both P perlatus and P brinckiBott 1960 in the Western Cape (Stewart 1997b) and P unispinus Stewart ampCook 1998 and P sidneyi in Mpumalanga (Stewart amp Cook 1998) An I -valueof 0599 was obtained separating P clarus Gouws Stewart amp Coke 2000 andP depressus (Gouws et al 2000) The only species in the genus delineated using ahigher I -value was P granularis Daniels Stewart amp Gibbons 1998 which wasseparated from P perlatus in the Olifants River at a I -value of 088 (Danielset al 1998a 1999) Although slightly higher than most interspeci c values inthe genus the value obtained in this study nevertheless falls within the range (035to 085) speci ed by Thorpe (1982) to indicate congeneric species differencesAllopatric populations showing I -values of less than 085 are unlikely to beconspeci c (Thorpe amp Soleacute-Cava 1994) With the exception of two cases allpairwise comparisons between allopatric populations of the two forms yieldedI -values less than 085

Identity-values were high for comparisons within both the form A (0949 to0986) and P sidneyi (0994 to 0999) groups Intraspeci c I -values are generallyhigh in the genus Potamonautes and disjunct populations within a species tendto be genetically undifferentiated Intraspeci c I -values obtained in six studies(Stewart 1997a b Stewart amp Cook 1998 Daniels et al 1998b 1999) involvingsix Potamonautes species varied from 0902 to 1000 (D D 0000 to 0103)An intraspeci c I -value of 075 was obtained in a comparison of two groups ofP brincki populations across the Cape Peninsula and Cape Flats However thismost probably indicates a species difference and requires further investigation(Stewart 1997b) Given the high intraspeci c I -values characteristic of the genusand those obtained for comparisons within each form the I -value obtainedfor the comparison between the two forms most likely represents a speciesdifference

Bock (1986) also de ned a species as possessing a set of three distinctcharacteristics genetic unity reproductive unity and ecological unity Biochemicaldata provide support for compliance with the rst two criteria for both formsWhile no empirical evidence is as yet available con rming the third factor adegree of macro- and microhabitat segregation and thus ecological segregationis evident between the two forms Potamonautes sidneyi is widespread acrossthe province (Stewart et al 1995) while the other form appears to have a

POTAMONAUTES LIVIDUS NOV 151

more limited distribution in northeastern KwaZulu-Natal restricted to patches ofswamp forest with particular oral assemblages The swamp forests are oftencharacterized by Barringtonia racemosa Syzygium cordatum Ficus trichopodaHibiscus tiliaceus L Rauvola caffra Sond Voacanga thouarsii Roem amp SchultRaphia australis Oberm amp Strey and Podocarpus falcatus (Thunb) R Br exMirb with the fern Stenochlaena tenuifolia (Desv) T Moore often present in theunderstorey (Bruton 1980 Moll 1980) Within the swamp forests the sympatricpopulations appear to show a degree of microhabitat segregation Observationssuggest that P sidneyi has a closer association with water as individuals were nevercollected great distances away from seepage pools and channels owing throughthe forest Conversely individuals of the swamp-forest form were most oftencollected farther from water and their burrows were often among the vegetationObservations suggest that this form is more terrestrial Individuals were noticedto move to higher elevations when the water table rose through the hydromorphicpeat soil ooding their burrows and the surface and they were also more active oncloudy overcast days Evidence of terrestrial adaptation is most likely to be foundin the structure and histology of the organs and tissues involved in respirationfactors such as branchial chamber shape and volume gill structure and formulaand the structure and vascularization of the branchiostegite lining are knownto re ect changes brought upon by the constraints of the terrestrial environment(Greenaway amp Taylor 1976 Diacuteaz amp Rodriacuteguez 1977 Taylor amp Greenaway1979 Cumberlidge 1986 1991 Takeda et al 1996) Although the availabilityof material prohibited the investigation of this aspect future research may prove tobe fruitful and highlight a greater distinction between the two forms

Studies on terrestrial adaptation supplemented by behavioural data that couldillustrate microhabitat and ecological segregation would quantify further thedegree of differentiation between the two forms However two independent datasets biochemical and morphological present strong evidence for the speci c statusof the swamp-forest form

TAXONOMY

Potamonautes lividus sp nov ( gs 6-7)

Material examined mdash Holotype South African Museum (SAM) A43540 one male CL D255 mm Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws andL Hoenson Allotype SAM A43541 one female CL D 245 mm Ficus and Barringtonia swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S 32plusmn2401800E)coll 27 January 1997 by B A Stewart G Gouws and L Hoenson Other material SAM A43542two males Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws

152 G GOUWS B A STEWART amp P E REAVELL

and L Hoenson SAM A43543 one female Lake Nhlabane north of Richards Bay (28plusmn3800500S32plusmn1601700E) coll 27 April 1993 by the University of Zululand Zoology Department SAMA43544 three males one female Mdibi swamp forest along Mdibi stream 8 km north of RichardsBay (28plusmn4202400S 32plusmn0902600E) coll 26 January 1997 by B A Stewart P A Cook M CokeP E Reavell G Gouws and L Hoenson SAM A43545 one male one female Syzygium forestUniversity of Zululand campus (28plusmn5102500S 31plusmn5100200E) coll 24 January 1997 by B A StewartP A Cook P E Reavell G Gouws and L Hoenson SAM A43546 two males two femalesUniversity of Zululand stream owing through campus (28plusmn550S 31plusmn410E) coll 10 September 1995by P E Reavell SAM A41313 one male one female swamp forest Empangeni (28plusmn5102500S31plusmn5100200E) coll 2 August 1994 by M Coke SAM A41155 one male University of ZululandSyzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S 31plusmn450E) coll 10 December1988 by P E Reavell SAM A41153 three males smaller holes in hydromorphic soil Syzygiumcordatum swamp forest University of Zululand (28plusmn450S 31plusmn450E) coll 20 March 1994 byP E Reavell SAM A41156 one female Syzygium cordatum swamp forest University of Zululand(28plusmn450S 31plusmn450E) coll 18 May 1992 by P E Reavell SAM A41154 one male one femaleUniversity of Zululand Syzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S31plusmn450E) coll 10 May 1990 by P E Reavell SAM A43547 two males one female swamp forestUniversity of Zululand (28plusmn450S 31plusmn450E) coll 1 April 1994 by P E Reavell SAM A43548one male one female Syzygium and Bridelia dominated swamp forest University of Zululand(28plusmn5102500S 31plusmn5100200E) coll 7 October 1996 by P E Reavell SAM A43549 one female Mdibiswamp forest Lake Msingazi catchment area north of Richards Bay (28plusmn420S 32plusmn090E) coll5 December 1996 by P E Reavell Albany Museum mdash GEN910 one female Mpolozi swampsMapelane (28plusmn2601300S 32plusmn2402500E) coll 13 February 1991 Albany Museum mdash GEN965 twomales ve females NrsquoKoninga Valley Richards Bay (28plusmn450S 32plusmn030E) coll 7 April 1988

Other material mdash The following specimens included in the collections of the South AfricanMuseum warrant further investigation as although they bear some resemblance to the speciesdescribed below their identi cation is uncertain SAM A41276 one male one female Mbonenidam Mkuze Game Reserve (27plusmn3705700S 32plusmn1504500E) coll 28 October 1994 by M Coke SAMA41299 two males Nxwala stream Mkuze Game Reserve (27plusmn4302300S 32plusmn1601000E) coll 10November 1994 by O Bourquin SAM A41277 one male Rainpool south of entrance False BayPark (28plusmn0000100S 32plusmn2102100E) coll 26 October 1994 by M Coke SAM A41300 two malesKangela rainpoolN2 near Mtubatuba (28plusmn2200000S 32plusmn1103600E) coll 25 October 1994 by M Cokeand SAM A41211 one male Ntambanana (Ntrabanana) Zululand coll by H H Curson

Type locality mdash South Africa KwaZulu-Natal Barringtonia and Ficus swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S32plusmn2401800E)

Distribution mdash At present known only from the swamp forests (characterizedby Barringtonia racemosa Syzygium cordatum and Ficus trichopoda vegetationand spongy hydromorphic peat-soil) in the vicinity of Richards Bay Empangeniand the Mapelane Nature Reserve It is probable that the distribution of the speciesmay extend into low-lying areas to the east of the Drakensberg escarpment in theprovince of Mpumalanga and into Mozambique

Etymology mdash From the Latin ldquolividusrdquo meaning ldquobluerdquo or ldquolight bluerdquoreferring to the characteristic silver-blue sheen of the carapace The epitheton isan adjective agreeing in gender with the (masculine) generic name

POTAMONAUTES LIVIDUS NOV 153

Fig 6 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A wholeanimal dorsal aspect B whole animal ventral aspect C cephalothorax frontal aspect

Diagnosis mdash Carapace distinctly vaulted and relatively narrow posteriorlyEpibranchial teeth absent and anterolateral margin of the carapace smooth Post-frontal crest indistinct medially with frontal lobe projecting downwards Cara-pace characteristically orange to red with silver-blue sheen Chelipeds and limbs

154 G GOUWS B A STEWART amp P E REAVELL

bright orange to red with lighter cheliped and dactyl tips Chela in ated and highlyarched

Description of male holotype mdash Size Measurements of the holotype and theranges of other specimens are given in table IV

Carapace ( gs 6A C 7A) Carapace and limbs characteristically orange tored with the carapace possessing a silver-blue sheen when alive Preserved spec-imens (70 ethanol) appear less orange and the carapace retains a blue-greycolour Cephalothorax ovoid distinctly vaulted branchial region highly convex( g 6A C) maximum height and width at anterior third (ratio CHCL D 065CWWCL D 145) Anterior margin straight Urogastric grooves moderately wellde ned Cardiac grooves shallow and poorly de ned Carapace otherwise smoothPostfrontal crest smooth curves forward medially Postfrontal crest diminishesabove inner orbit margins though well de ned immediately lateral to forked mid-point groove by means of two indentations anterior to crest indicating epigas-tric lobes Exorbital teeth moderately sharp but small Epibranchial teeth ab-sent Anterolateral margin posterior to postfrontal crest smooth margin curvingin over carapace in branchial region though indistinctly Each ank has a longitu-dinal groove dividing the subhepatic from the pterygostomial region with verticalgroove running from longitudinal groove joining anterolateral margin between ex-orbital tooth and postfrontal crest

Sternites ( gs 6B 7B) Sternites 1 and 2 fused no suture visible First suture(sternal groove) between sternites 2 and 3 complete Second sternal groove

TABLE IVPotamonautes lividus sp nov wet weight (in g) and measurements (in mm) for the male holotype

and ranges for other individuals examined (maximum of 77 males and 70 females)

Variable Abbreviation Holotype Males Females

Wet weight WW 242 05-214 07-183Carapace length CL 255 84-247 89-276Carapace widest width CWW 370 114-360 118-373Carapace posterior width CWP 281 90-269 86-306Distance between postfrontal crest

and anterior margin PFCD 43 12-222 15-46Distance between orbits ED 114 42-119 43-123Distance between exorbital teeth CWA 259 96-254 96-262Carapace height CH 165 48-171 50-162Width of sixth abdominal segment AW6 75 28-74 31-240Major cheliped propodus length MCPL 427 71-402 76-291Major cheliped propodus height MCPH 198 28-189 28-142Pereopod 2 merus length P2ML 189 50-181 51-171Pereopod 2 merus width P2MW 58 19-56 18-59

POTAMONAUTES LIVIDUS NOV 155

Fig 7 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A carapaceoutline B thoracic sternum C right cheliped dactylus and propodus D left cheliped dactylusand propodus E left third maxilliped F left mandible and mandibular palp posterior view G leftmandibular palp posterior view H left mandibular palp anterior view I left gonopod 1 anteriorview J terminal segment left gonopod 1 anterior view K left gonopod 1 posterior view L leftgonopod 2 anterior view Scale lines represent 1 mm except for A-D where they represent 10 mm

156 G GOUWS B A STEWART amp P E REAVELL

between sternites 3 and 4 complete laterally becoming shallower mediallysloping sharply towards abdominopelvic region

Third maxillipeds ( gs 6C 7E) Filling entire buccal frame except for ovalefferent respiratory openings short agellum present on exopods ischium smoothwith moderately deep vertical groove

Mandibular palp ( g 7F G H) Mandibular palp with two segments terminalsegment undivided with a dense tuft of setae on posterior surface of angeof terminal segment Margins generally hirsute Subterminal segment slightlyenlarged distally

Chelipeds and walking legs ( gs 6A 7C D) Chelipeds markedly unequaldactylus of right cheliped strongly arched 163 times length of dactylus of leftcheliped Both dactyli armed with up to 20 cutting teeth three to four of whichare slightly larger and more prominent Propodus of right cheliped markedlyin ated 168 times longer and 20 times wider than that of left cheliped Pollexpossesses 20 cutting teeth four to ve of which are more prominent Carpi ofboth chelipeds possess one prominent and three rudimentary teeth Margins ofmeri granulose small blunt spine on anterior surface no spine on anterior-inferiormargin Pereopods generally slender (pereopod 2 merus length width D 328 andpereopod 5 merus lengthwidth D 271) P3 longest P5 shortest ventral marginsof propodi and meri smooth dorsal margin with ne sharp bristles dactyli endingin sharp points with margins bearing a series of sharp spinelike bristles

Pleon ( gs 6B 7B) First ve segments broad and short last two segmentslonger terminal segment rounded at distal end

Pleopods ( g 7I J K) Pleopod 1 (gonopod 1) terminal segment short 025times length of subterminal segment terminal segment curves away from mid-line when viewed posteriorly widest at base ending in pointed tip Subterminalsegment of pleopod 1 tapers distally inner lateral margin slightly irregular outerlateral margin straighter both margins hirsute Posterior surface with twisting lon-gitudinal groove extending length of subterminal and terminal segment Groovenot visible on anterior surface Posterior surface and margins of groove hirsutePleopod 2 (gonopod 2) terminal segment lament-like 05 the length of subter-minal segment curving slightly towards medial line proximally curves away frommedial line distally ( g 7L) Subterminal segment widest at base tapering sharplyinwards at 04 of length forms narrow process supporting terminal segment

Variation mdash All individuals are characteristically dark orange to red witha silver-blue sheen to the carapace while the chelipeds vary in colour frombright orange-red to a lighter yellow-orange All individuals are characterized byhighly vaulted carapaces and downwardly projecting frontal lobes The postfrontalcrest which is most pronounced laterally (from directly above the orbits to theanterolateral margin) and incomplete medially is often more distinct in the smaller

POTAMONAUTES LIVIDUS NOV 157

individuals Chelipeds are not always typically arched enclosing a large ovoidspace as in the holotype Chelipeds of smaller individuals although in ated areless arched and often tight closing with the small cutting teeth more obviousChelipeds of females and small males in particular from the Mdibi and Universityof Zululand localities have propodi that are relatively high with in ated palmsand relatively short tightly closing chelae which project slightly downwardsHeterochely has been demonstrated in most Potamonautes-species occurring inSouth Africa (Siegfried 1972 Raubenheimer 1986 Stewart et al 1995 Stewart1997a b Stewart amp Cook 1998 Daniels et al 1998a Gouws et al 2000) Withinthe species 76 of the specimens were right-handed with 11 being left-handedand 13 being of equal or subequal (differing by less than one millimeter) sizeOf the males 79 were right-handed 8 left-handed and 13 equal or subequalFemales had 74 right-handedness 13 left-handedness and in 13 of caseschelipeds were equal or subequal The abdomen of mature females completelyoverlaps the coxae of the pereopods The smallest mature female had a CL of167 mm with the largest immature female having a CL of 159 indicating that thepubertal moult occurs approximately between the 14 mm and 18 mm size classes

Remarks mdash Potamonautes lividus sp nov can readily be distinguished from theten other species in the genus Potamonautes known to occur within South AfricaPotamonautes warreni Calman 1918 P dentatus P parvispina and P unispinusall bear a singular spine or a series of teeth on the anterolateral margins whereasP lividus sp nov is smooth Potamonautes perlatus P sidneyi and P granularisare all larger crabs with in ated arched carapaces with complete distinct post-frontal crests and scabrosity or granulation of the anterior margins orbits epi-branchial corners or postfrontal crests Potamonautes lividus sp nov has smoothcarapace margins and a incomplete postfrontal crest The terminal segment ofgonopod 1 in P lividus sp nov is relatively short and triangular and curves awayfrom the medial line when viewed posteriorly while that of P sidneyi is relativelylonger more slender and more S-shaped The postfrontal crest of P sidneyi mayjoin the anterolateral margin at a relatively sharp angle and form a pronouncedepibranchial corner along the anterolateral margin The anterolateral margin inP lividus sp nov is more rounded and the epibranchial corners slope down to-wards the anks Potamonautes granularis is chocolate brown with orange tips tothe chelipeds Potamonautes brincki is a smaller crab with a smoother carapacethough also chocolate to reddish-brown in colour with a nely granulated antero-lateral margin which does not curve in over the carapace in the branchial region(Stewart 1997b) Potamonautes depressus and P clarus both have rounded epi-branchial corners and smooth carapaces though these are relatively shallow andhave attened dorsal surfaces Both are characterized by long slender limbs Pota-monautes depressus is brown to green-brown in colour while P clarus is brightorange in colour

158 G GOUWS B A STEWART amp P E REAVELL

A number of species from further a eld bear a super cial resemblance toP lividus sp nov particularly with regard to carapace morphology though in mostcases they can be readily distinguished Potamonautes pilosus Hilgendorf 1898 isknown from East Africa and is a small crab with a CWW of less than 25 mmSpecimens possess a weak postfrontal crest which along with the anterolateralmargin can be granulated (Hilgendorf 1898 Bott 1955) Potamonautes neumanniHilgendorf 1898 is known from East Africa and has a characteristically vaultedcarapace without a complete distinct postfrontal crest (Hilgendorf 1898 Bott1955) The postfrontal crest is more distinct in P lividus particularly laterally andthe exorbital teeth are sharper and more de ned in P lividus than in P neumanniThe terminal segment of gonopod 1 is longer and more slender in P neumannithan in P lividus and curves distinctly outwards The subterminal segment ofgonopod 1 is wider at its apex in P neumanni than in P lividus Additionally thecarapace of preserved specimens of P neumanni is typically grey in colour whileliving specimens are violet in colour with bright olive-green limbs and chelipeds(Hilgendorf 1898) Potamonautes ballayi acristatus Bott 1955 has an incompletepostfrontal crest only present above the orbits and small and blunt exorbital teethThe major chela although highly arched and the minor chela are long and moreslender than those of P lividus sp nov The terminal segment of gonopod 1 ofP granviki Colosi 1924 is curved towards the medial line when viewed posteriorly(Bott 1955) The chelae of both P berardi berardi Audouin 1826 and P b ignestiiParisi 1923 are relatively short and high with stout downward-projecting ngersThe anterior margin of the frontal lobe of P b berardi shows a distinct invaginationand the anterolateral margin appears sharp and less rounded than in P lividus spnov while the postfrontal crest of P b ignestii is complete and has a fairly longmedial groove Potamonautes emini emini Hilgendorf 1892 are generally smallcrabs with a less in ated carapace and short stout chelipeds The subterminaland terminal segments of gonopod 1 are of more or less equal size (Bott 1955)Potamonautes e semilunaris Bott 1955 and P luashiensis Bott 1955 are alsosmall crabs (CWW lt 20 mm) with the postfrontal crest only visible laterally andin the case of P luashiensis the anterolateral margin and postfrontal crest mayshow granulation Potamonautes didieri Rathbun 1904 possesses a more completerounded postfrontal crest and shorter more stout chelipeds (Bott 1955)

ACKNOWLEDGEMENTS

Financial assistance was kindly provided by the World Wildlife Fund - SouthAfrica the Foundation for Research Development and the University of ZululandThe KwaZulu-Natal Nature Conservation Services provided accommodation and

POTAMONAUTES LIVIDUS NOV 159

logistic support Liz Hoenson Peter Cook Mike Coke and Tyrone Ridgway arethanked for assistance in the eld and Michelle van der Merwe is thanked foraiding in the photography and drafting of gures The authors wish to thank ananonymous reviewer for comments on the manuscript

REFERENCES

BARNARD K H 1935 Scienti c results of the Vernay-Lang Kalahari expedition March toSeptember 1930 Crustacea Ann Transvaal Mus 16 481-492

mdash mdash 1950 Descriptive catalogue of South African decapod Crustacea (crabs and shrimps) AnnSouth African Mus 38 1-837

BOCK W J 1986 Species concepts speciation and macroevolution In K IWATSUKIP H RAVEN amp W J BOCK (eds) Modern aspects of species 31-57 (University of TokyoPress Tokyo)

BOTT R 1955 Die Suumlsswasserkrabben von Afrika (Crust Decap) und ihre StammesgeschichteAnn Mus R Congo Belge (C Zool) 1 (33) 209-352 pls 1-30

BRUTON M N 1980 An outline of the ecology of the Mgobezeleni lake system at Sodwana withemphasis on the mangrove community In M N BRUTON amp K H COOPER (eds) Studieson the ecology of Maputaland 408-426 (Rhodes University Grahamstown)

CUMBERLIDGE N 1986 Ventilation of the branchial chambers in the amphibious West Africanfreshwater crab Sudanonautes (Convexonautes) aubryi monodi (Balss 1929) (BrachyuraPotamonautidae)Hydrobiol 134 53-65

mdash mdash 1991 The respiratory system of Globonautes macropus (Rathbun 1898) a terrestrialfreshwater crab from Liberia (GecarcinucoideaGecarcinucidae)Crustaceana 61 (1) 69-80

DANIELS S R B A STEWART amp M J GIBBONS 1998a Potamonautes granularis sp nov(Brachyura Potamonautidae) a new cryptic species of river crab from the Olifants Riversystem South Africa Crustaceana 71 (8) 885-903

mdash mdash mdash mdash amp mdash mdash 1998b Genetic and morphometric variation in the potamonautid river crabPotamonautes parvispina (Decapoda Potamonautidae) from two Western Cape rivers SouthAfrica Journ nat Hist London 32 1245-1258

mdash mdash mdash mdash amp mdash mdash 1999 Genetic structure among populations of Potamonautes perlatus(Decapoda Potamonautidae) from the Olifants River system in the Western Cape SouthAfrica Journ Zool London 249 (2) 137-142

DIacuteAZ H amp G RODRIacuteGUEZ 1977 The branchial chamber in terrestrial crabs a comparative studyBiol Bull Woods Hole 153 485-504

GOUWS G B A STEWART amp M COKE 2000 Evidence for a new species of river crab(Decapoda Brachyura Potamonautidae) from the Drakensberg South Africa Journ CrustBiol 20 (4) 743-758

GREENAWAY P amp H H TAYLOR 1976 Aerial gas exchange in Australian arid-zone crabParathelphusa transversa Von Martens Nature London 262 711-713

HILGENDORF F 1898 Die Land- und Suumlsswasser-Dekapoden Ostafrikas Die Thierwelt DeutschOst-Afrikas 4 (7) 1-37

LENZ H 1912 Afrikanische Crustaceen aus schwedischen Sammlungen Ark Zool 7 (29) 1-10MARKERT C L amp I FAULHABER 1965 Lactate dehydrogenase isozyme patterns of sh Journ

exp Zool 159 319-332MAYR E 1963 Animal species and evolution i-xiv 1-797 (Harvard University Press Cambridge

Massachusetts)mdash mdash 1970 Populations species and evolution i-xv 1-453 (Harvard University Press Cambridge

Massachusetts)

POTAMONAUTES LIVIDUS NOV 151

more limited distribution in northeastern KwaZulu-Natal restricted to patches ofswamp forest with particular oral assemblages The swamp forests are oftencharacterized by Barringtonia racemosa Syzygium cordatum Ficus trichopodaHibiscus tiliaceus L Rauvola caffra Sond Voacanga thouarsii Roem amp SchultRaphia australis Oberm amp Strey and Podocarpus falcatus (Thunb) R Br exMirb with the fern Stenochlaena tenuifolia (Desv) T Moore often present in theunderstorey (Bruton 1980 Moll 1980) Within the swamp forests the sympatricpopulations appear to show a degree of microhabitat segregation Observationssuggest that P sidneyi has a closer association with water as individuals were nevercollected great distances away from seepage pools and channels owing throughthe forest Conversely individuals of the swamp-forest form were most oftencollected farther from water and their burrows were often among the vegetationObservations suggest that this form is more terrestrial Individuals were noticedto move to higher elevations when the water table rose through the hydromorphicpeat soil ooding their burrows and the surface and they were also more active oncloudy overcast days Evidence of terrestrial adaptation is most likely to be foundin the structure and histology of the organs and tissues involved in respirationfactors such as branchial chamber shape and volume gill structure and formulaand the structure and vascularization of the branchiostegite lining are knownto re ect changes brought upon by the constraints of the terrestrial environment(Greenaway amp Taylor 1976 Diacuteaz amp Rodriacuteguez 1977 Taylor amp Greenaway1979 Cumberlidge 1986 1991 Takeda et al 1996) Although the availabilityof material prohibited the investigation of this aspect future research may prove tobe fruitful and highlight a greater distinction between the two forms

Studies on terrestrial adaptation supplemented by behavioural data that couldillustrate microhabitat and ecological segregation would quantify further thedegree of differentiation between the two forms However two independent datasets biochemical and morphological present strong evidence for the speci c statusof the swamp-forest form

TAXONOMY

Potamonautes lividus sp nov ( gs 6-7)

Material examined mdash Holotype South African Museum (SAM) A43540 one male CL D255 mm Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws andL Hoenson Allotype SAM A43541 one female CL D 245 mm Ficus and Barringtonia swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S 32plusmn2401800E)coll 27 January 1997 by B A Stewart G Gouws and L Hoenson Other material SAM A43542two males Ficus and Barringtonia swamp forest next to road 8 km from rest camp MapelaneNature Reserve (28plusmn2701100S 32plusmn2401800E) coll 27 January 1997 by B A Stewart G Gouws

152 G GOUWS B A STEWART amp P E REAVELL

and L Hoenson SAM A43543 one female Lake Nhlabane north of Richards Bay (28plusmn3800500S32plusmn1601700E) coll 27 April 1993 by the University of Zululand Zoology Department SAMA43544 three males one female Mdibi swamp forest along Mdibi stream 8 km north of RichardsBay (28plusmn4202400S 32plusmn0902600E) coll 26 January 1997 by B A Stewart P A Cook M CokeP E Reavell G Gouws and L Hoenson SAM A43545 one male one female Syzygium forestUniversity of Zululand campus (28plusmn5102500S 31plusmn5100200E) coll 24 January 1997 by B A StewartP A Cook P E Reavell G Gouws and L Hoenson SAM A43546 two males two femalesUniversity of Zululand stream owing through campus (28plusmn550S 31plusmn410E) coll 10 September 1995by P E Reavell SAM A41313 one male one female swamp forest Empangeni (28plusmn5102500S31plusmn5100200E) coll 2 August 1994 by M Coke SAM A41155 one male University of ZululandSyzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S 31plusmn450E) coll 10 December1988 by P E Reavell SAM A41153 three males smaller holes in hydromorphic soil Syzygiumcordatum swamp forest University of Zululand (28plusmn450S 31plusmn450E) coll 20 March 1994 byP E Reavell SAM A41156 one female Syzygium cordatum swamp forest University of Zululand(28plusmn450S 31plusmn450E) coll 18 May 1992 by P E Reavell SAM A41154 one male one femaleUniversity of Zululand Syzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S31plusmn450E) coll 10 May 1990 by P E Reavell SAM A43547 two males one female swamp forestUniversity of Zululand (28plusmn450S 31plusmn450E) coll 1 April 1994 by P E Reavell SAM A43548one male one female Syzygium and Bridelia dominated swamp forest University of Zululand(28plusmn5102500S 31plusmn5100200E) coll 7 October 1996 by P E Reavell SAM A43549 one female Mdibiswamp forest Lake Msingazi catchment area north of Richards Bay (28plusmn420S 32plusmn090E) coll5 December 1996 by P E Reavell Albany Museum mdash GEN910 one female Mpolozi swampsMapelane (28plusmn2601300S 32plusmn2402500E) coll 13 February 1991 Albany Museum mdash GEN965 twomales ve females NrsquoKoninga Valley Richards Bay (28plusmn450S 32plusmn030E) coll 7 April 1988

Other material mdash The following specimens included in the collections of the South AfricanMuseum warrant further investigation as although they bear some resemblance to the speciesdescribed below their identi cation is uncertain SAM A41276 one male one female Mbonenidam Mkuze Game Reserve (27plusmn3705700S 32plusmn1504500E) coll 28 October 1994 by M Coke SAMA41299 two males Nxwala stream Mkuze Game Reserve (27plusmn4302300S 32plusmn1601000E) coll 10November 1994 by O Bourquin SAM A41277 one male Rainpool south of entrance False BayPark (28plusmn0000100S 32plusmn2102100E) coll 26 October 1994 by M Coke SAM A41300 two malesKangela rainpoolN2 near Mtubatuba (28plusmn2200000S 32plusmn1103600E) coll 25 October 1994 by M Cokeand SAM A41211 one male Ntambanana (Ntrabanana) Zululand coll by H H Curson

Type locality mdash South Africa KwaZulu-Natal Barringtonia and Ficus swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S32plusmn2401800E)

Distribution mdash At present known only from the swamp forests (characterizedby Barringtonia racemosa Syzygium cordatum and Ficus trichopoda vegetationand spongy hydromorphic peat-soil) in the vicinity of Richards Bay Empangeniand the Mapelane Nature Reserve It is probable that the distribution of the speciesmay extend into low-lying areas to the east of the Drakensberg escarpment in theprovince of Mpumalanga and into Mozambique

Etymology mdash From the Latin ldquolividusrdquo meaning ldquobluerdquo or ldquolight bluerdquoreferring to the characteristic silver-blue sheen of the carapace The epitheton isan adjective agreeing in gender with the (masculine) generic name

POTAMONAUTES LIVIDUS NOV 153

Fig 6 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A wholeanimal dorsal aspect B whole animal ventral aspect C cephalothorax frontal aspect

Diagnosis mdash Carapace distinctly vaulted and relatively narrow posteriorlyEpibranchial teeth absent and anterolateral margin of the carapace smooth Post-frontal crest indistinct medially with frontal lobe projecting downwards Cara-pace characteristically orange to red with silver-blue sheen Chelipeds and limbs

154 G GOUWS B A STEWART amp P E REAVELL

bright orange to red with lighter cheliped and dactyl tips Chela in ated and highlyarched

Description of male holotype mdash Size Measurements of the holotype and theranges of other specimens are given in table IV

Carapace ( gs 6A C 7A) Carapace and limbs characteristically orange tored with the carapace possessing a silver-blue sheen when alive Preserved spec-imens (70 ethanol) appear less orange and the carapace retains a blue-greycolour Cephalothorax ovoid distinctly vaulted branchial region highly convex( g 6A C) maximum height and width at anterior third (ratio CHCL D 065CWWCL D 145) Anterior margin straight Urogastric grooves moderately wellde ned Cardiac grooves shallow and poorly de ned Carapace otherwise smoothPostfrontal crest smooth curves forward medially Postfrontal crest diminishesabove inner orbit margins though well de ned immediately lateral to forked mid-point groove by means of two indentations anterior to crest indicating epigas-tric lobes Exorbital teeth moderately sharp but small Epibranchial teeth ab-sent Anterolateral margin posterior to postfrontal crest smooth margin curvingin over carapace in branchial region though indistinctly Each ank has a longitu-dinal groove dividing the subhepatic from the pterygostomial region with verticalgroove running from longitudinal groove joining anterolateral margin between ex-orbital tooth and postfrontal crest

Sternites ( gs 6B 7B) Sternites 1 and 2 fused no suture visible First suture(sternal groove) between sternites 2 and 3 complete Second sternal groove

TABLE IVPotamonautes lividus sp nov wet weight (in g) and measurements (in mm) for the male holotype

and ranges for other individuals examined (maximum of 77 males and 70 females)

Variable Abbreviation Holotype Males Females

Wet weight WW 242 05-214 07-183Carapace length CL 255 84-247 89-276Carapace widest width CWW 370 114-360 118-373Carapace posterior width CWP 281 90-269 86-306Distance between postfrontal crest

and anterior margin PFCD 43 12-222 15-46Distance between orbits ED 114 42-119 43-123Distance between exorbital teeth CWA 259 96-254 96-262Carapace height CH 165 48-171 50-162Width of sixth abdominal segment AW6 75 28-74 31-240Major cheliped propodus length MCPL 427 71-402 76-291Major cheliped propodus height MCPH 198 28-189 28-142Pereopod 2 merus length P2ML 189 50-181 51-171Pereopod 2 merus width P2MW 58 19-56 18-59

POTAMONAUTES LIVIDUS NOV 155

Fig 7 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A carapaceoutline B thoracic sternum C right cheliped dactylus and propodus D left cheliped dactylusand propodus E left third maxilliped F left mandible and mandibular palp posterior view G leftmandibular palp posterior view H left mandibular palp anterior view I left gonopod 1 anteriorview J terminal segment left gonopod 1 anterior view K left gonopod 1 posterior view L leftgonopod 2 anterior view Scale lines represent 1 mm except for A-D where they represent 10 mm

156 G GOUWS B A STEWART amp P E REAVELL

between sternites 3 and 4 complete laterally becoming shallower mediallysloping sharply towards abdominopelvic region

Third maxillipeds ( gs 6C 7E) Filling entire buccal frame except for ovalefferent respiratory openings short agellum present on exopods ischium smoothwith moderately deep vertical groove

Mandibular palp ( g 7F G H) Mandibular palp with two segments terminalsegment undivided with a dense tuft of setae on posterior surface of angeof terminal segment Margins generally hirsute Subterminal segment slightlyenlarged distally

Chelipeds and walking legs ( gs 6A 7C D) Chelipeds markedly unequaldactylus of right cheliped strongly arched 163 times length of dactylus of leftcheliped Both dactyli armed with up to 20 cutting teeth three to four of whichare slightly larger and more prominent Propodus of right cheliped markedlyin ated 168 times longer and 20 times wider than that of left cheliped Pollexpossesses 20 cutting teeth four to ve of which are more prominent Carpi ofboth chelipeds possess one prominent and three rudimentary teeth Margins ofmeri granulose small blunt spine on anterior surface no spine on anterior-inferiormargin Pereopods generally slender (pereopod 2 merus length width D 328 andpereopod 5 merus lengthwidth D 271) P3 longest P5 shortest ventral marginsof propodi and meri smooth dorsal margin with ne sharp bristles dactyli endingin sharp points with margins bearing a series of sharp spinelike bristles

Pleon ( gs 6B 7B) First ve segments broad and short last two segmentslonger terminal segment rounded at distal end

Pleopods ( g 7I J K) Pleopod 1 (gonopod 1) terminal segment short 025times length of subterminal segment terminal segment curves away from mid-line when viewed posteriorly widest at base ending in pointed tip Subterminalsegment of pleopod 1 tapers distally inner lateral margin slightly irregular outerlateral margin straighter both margins hirsute Posterior surface with twisting lon-gitudinal groove extending length of subterminal and terminal segment Groovenot visible on anterior surface Posterior surface and margins of groove hirsutePleopod 2 (gonopod 2) terminal segment lament-like 05 the length of subter-minal segment curving slightly towards medial line proximally curves away frommedial line distally ( g 7L) Subterminal segment widest at base tapering sharplyinwards at 04 of length forms narrow process supporting terminal segment

Variation mdash All individuals are characteristically dark orange to red witha silver-blue sheen to the carapace while the chelipeds vary in colour frombright orange-red to a lighter yellow-orange All individuals are characterized byhighly vaulted carapaces and downwardly projecting frontal lobes The postfrontalcrest which is most pronounced laterally (from directly above the orbits to theanterolateral margin) and incomplete medially is often more distinct in the smaller

POTAMONAUTES LIVIDUS NOV 157

individuals Chelipeds are not always typically arched enclosing a large ovoidspace as in the holotype Chelipeds of smaller individuals although in ated areless arched and often tight closing with the small cutting teeth more obviousChelipeds of females and small males in particular from the Mdibi and Universityof Zululand localities have propodi that are relatively high with in ated palmsand relatively short tightly closing chelae which project slightly downwardsHeterochely has been demonstrated in most Potamonautes-species occurring inSouth Africa (Siegfried 1972 Raubenheimer 1986 Stewart et al 1995 Stewart1997a b Stewart amp Cook 1998 Daniels et al 1998a Gouws et al 2000) Withinthe species 76 of the specimens were right-handed with 11 being left-handedand 13 being of equal or subequal (differing by less than one millimeter) sizeOf the males 79 were right-handed 8 left-handed and 13 equal or subequalFemales had 74 right-handedness 13 left-handedness and in 13 of caseschelipeds were equal or subequal The abdomen of mature females completelyoverlaps the coxae of the pereopods The smallest mature female had a CL of167 mm with the largest immature female having a CL of 159 indicating that thepubertal moult occurs approximately between the 14 mm and 18 mm size classes

Remarks mdash Potamonautes lividus sp nov can readily be distinguished from theten other species in the genus Potamonautes known to occur within South AfricaPotamonautes warreni Calman 1918 P dentatus P parvispina and P unispinusall bear a singular spine or a series of teeth on the anterolateral margins whereasP lividus sp nov is smooth Potamonautes perlatus P sidneyi and P granularisare all larger crabs with in ated arched carapaces with complete distinct post-frontal crests and scabrosity or granulation of the anterior margins orbits epi-branchial corners or postfrontal crests Potamonautes lividus sp nov has smoothcarapace margins and a incomplete postfrontal crest The terminal segment ofgonopod 1 in P lividus sp nov is relatively short and triangular and curves awayfrom the medial line when viewed posteriorly while that of P sidneyi is relativelylonger more slender and more S-shaped The postfrontal crest of P sidneyi mayjoin the anterolateral margin at a relatively sharp angle and form a pronouncedepibranchial corner along the anterolateral margin The anterolateral margin inP lividus sp nov is more rounded and the epibranchial corners slope down to-wards the anks Potamonautes granularis is chocolate brown with orange tips tothe chelipeds Potamonautes brincki is a smaller crab with a smoother carapacethough also chocolate to reddish-brown in colour with a nely granulated antero-lateral margin which does not curve in over the carapace in the branchial region(Stewart 1997b) Potamonautes depressus and P clarus both have rounded epi-branchial corners and smooth carapaces though these are relatively shallow andhave attened dorsal surfaces Both are characterized by long slender limbs Pota-monautes depressus is brown to green-brown in colour while P clarus is brightorange in colour

158 G GOUWS B A STEWART amp P E REAVELL

A number of species from further a eld bear a super cial resemblance toP lividus sp nov particularly with regard to carapace morphology though in mostcases they can be readily distinguished Potamonautes pilosus Hilgendorf 1898 isknown from East Africa and is a small crab with a CWW of less than 25 mmSpecimens possess a weak postfrontal crest which along with the anterolateralmargin can be granulated (Hilgendorf 1898 Bott 1955) Potamonautes neumanniHilgendorf 1898 is known from East Africa and has a characteristically vaultedcarapace without a complete distinct postfrontal crest (Hilgendorf 1898 Bott1955) The postfrontal crest is more distinct in P lividus particularly laterally andthe exorbital teeth are sharper and more de ned in P lividus than in P neumanniThe terminal segment of gonopod 1 is longer and more slender in P neumannithan in P lividus and curves distinctly outwards The subterminal segment ofgonopod 1 is wider at its apex in P neumanni than in P lividus Additionally thecarapace of preserved specimens of P neumanni is typically grey in colour whileliving specimens are violet in colour with bright olive-green limbs and chelipeds(Hilgendorf 1898) Potamonautes ballayi acristatus Bott 1955 has an incompletepostfrontal crest only present above the orbits and small and blunt exorbital teethThe major chela although highly arched and the minor chela are long and moreslender than those of P lividus sp nov The terminal segment of gonopod 1 ofP granviki Colosi 1924 is curved towards the medial line when viewed posteriorly(Bott 1955) The chelae of both P berardi berardi Audouin 1826 and P b ignestiiParisi 1923 are relatively short and high with stout downward-projecting ngersThe anterior margin of the frontal lobe of P b berardi shows a distinct invaginationand the anterolateral margin appears sharp and less rounded than in P lividus spnov while the postfrontal crest of P b ignestii is complete and has a fairly longmedial groove Potamonautes emini emini Hilgendorf 1892 are generally smallcrabs with a less in ated carapace and short stout chelipeds The subterminaland terminal segments of gonopod 1 are of more or less equal size (Bott 1955)Potamonautes e semilunaris Bott 1955 and P luashiensis Bott 1955 are alsosmall crabs (CWW lt 20 mm) with the postfrontal crest only visible laterally andin the case of P luashiensis the anterolateral margin and postfrontal crest mayshow granulation Potamonautes didieri Rathbun 1904 possesses a more completerounded postfrontal crest and shorter more stout chelipeds (Bott 1955)

ACKNOWLEDGEMENTS

Financial assistance was kindly provided by the World Wildlife Fund - SouthAfrica the Foundation for Research Development and the University of ZululandThe KwaZulu-Natal Nature Conservation Services provided accommodation and

POTAMONAUTES LIVIDUS NOV 159

logistic support Liz Hoenson Peter Cook Mike Coke and Tyrone Ridgway arethanked for assistance in the eld and Michelle van der Merwe is thanked foraiding in the photography and drafting of gures The authors wish to thank ananonymous reviewer for comments on the manuscript

REFERENCES

BARNARD K H 1935 Scienti c results of the Vernay-Lang Kalahari expedition March toSeptember 1930 Crustacea Ann Transvaal Mus 16 481-492

mdash mdash 1950 Descriptive catalogue of South African decapod Crustacea (crabs and shrimps) AnnSouth African Mus 38 1-837

BOCK W J 1986 Species concepts speciation and macroevolution In K IWATSUKIP H RAVEN amp W J BOCK (eds) Modern aspects of species 31-57 (University of TokyoPress Tokyo)

BOTT R 1955 Die Suumlsswasserkrabben von Afrika (Crust Decap) und ihre StammesgeschichteAnn Mus R Congo Belge (C Zool) 1 (33) 209-352 pls 1-30

BRUTON M N 1980 An outline of the ecology of the Mgobezeleni lake system at Sodwana withemphasis on the mangrove community In M N BRUTON amp K H COOPER (eds) Studieson the ecology of Maputaland 408-426 (Rhodes University Grahamstown)

CUMBERLIDGE N 1986 Ventilation of the branchial chambers in the amphibious West Africanfreshwater crab Sudanonautes (Convexonautes) aubryi monodi (Balss 1929) (BrachyuraPotamonautidae)Hydrobiol 134 53-65

mdash mdash 1991 The respiratory system of Globonautes macropus (Rathbun 1898) a terrestrialfreshwater crab from Liberia (GecarcinucoideaGecarcinucidae)Crustaceana 61 (1) 69-80

DANIELS S R B A STEWART amp M J GIBBONS 1998a Potamonautes granularis sp nov(Brachyura Potamonautidae) a new cryptic species of river crab from the Olifants Riversystem South Africa Crustaceana 71 (8) 885-903

mdash mdash mdash mdash amp mdash mdash 1998b Genetic and morphometric variation in the potamonautid river crabPotamonautes parvispina (Decapoda Potamonautidae) from two Western Cape rivers SouthAfrica Journ nat Hist London 32 1245-1258

mdash mdash mdash mdash amp mdash mdash 1999 Genetic structure among populations of Potamonautes perlatus(Decapoda Potamonautidae) from the Olifants River system in the Western Cape SouthAfrica Journ Zool London 249 (2) 137-142

DIacuteAZ H amp G RODRIacuteGUEZ 1977 The branchial chamber in terrestrial crabs a comparative studyBiol Bull Woods Hole 153 485-504

GOUWS G B A STEWART amp M COKE 2000 Evidence for a new species of river crab(Decapoda Brachyura Potamonautidae) from the Drakensberg South Africa Journ CrustBiol 20 (4) 743-758

GREENAWAY P amp H H TAYLOR 1976 Aerial gas exchange in Australian arid-zone crabParathelphusa transversa Von Martens Nature London 262 711-713

HILGENDORF F 1898 Die Land- und Suumlsswasser-Dekapoden Ostafrikas Die Thierwelt DeutschOst-Afrikas 4 (7) 1-37

LENZ H 1912 Afrikanische Crustaceen aus schwedischen Sammlungen Ark Zool 7 (29) 1-10MARKERT C L amp I FAULHABER 1965 Lactate dehydrogenase isozyme patterns of sh Journ

exp Zool 159 319-332MAYR E 1963 Animal species and evolution i-xiv 1-797 (Harvard University Press Cambridge

Massachusetts)mdash mdash 1970 Populations species and evolution i-xv 1-453 (Harvard University Press Cambridge

Massachusetts)

152 G GOUWS B A STEWART amp P E REAVELL

and L Hoenson SAM A43543 one female Lake Nhlabane north of Richards Bay (28plusmn3800500S32plusmn1601700E) coll 27 April 1993 by the University of Zululand Zoology Department SAMA43544 three males one female Mdibi swamp forest along Mdibi stream 8 km north of RichardsBay (28plusmn4202400S 32plusmn0902600E) coll 26 January 1997 by B A Stewart P A Cook M CokeP E Reavell G Gouws and L Hoenson SAM A43545 one male one female Syzygium forestUniversity of Zululand campus (28plusmn5102500S 31plusmn5100200E) coll 24 January 1997 by B A StewartP A Cook P E Reavell G Gouws and L Hoenson SAM A43546 two males two femalesUniversity of Zululand stream owing through campus (28plusmn550S 31plusmn410E) coll 10 September 1995by P E Reavell SAM A41313 one male one female swamp forest Empangeni (28plusmn5102500S31plusmn5100200E) coll 2 August 1994 by M Coke SAM A41155 one male University of ZululandSyzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S 31plusmn450E) coll 10 December1988 by P E Reavell SAM A41153 three males smaller holes in hydromorphic soil Syzygiumcordatum swamp forest University of Zululand (28plusmn450S 31plusmn450E) coll 20 March 1994 byP E Reavell SAM A41156 one female Syzygium cordatum swamp forest University of Zululand(28plusmn450S 31plusmn450E) coll 18 May 1992 by P E Reavell SAM A41154 one male one femaleUniversity of Zululand Syzygium cordatum swamp forest holes in hydromorphic soil (28plusmn450S31plusmn450E) coll 10 May 1990 by P E Reavell SAM A43547 two males one female swamp forestUniversity of Zululand (28plusmn450S 31plusmn450E) coll 1 April 1994 by P E Reavell SAM A43548one male one female Syzygium and Bridelia dominated swamp forest University of Zululand(28plusmn5102500S 31plusmn5100200E) coll 7 October 1996 by P E Reavell SAM A43549 one female Mdibiswamp forest Lake Msingazi catchment area north of Richards Bay (28plusmn420S 32plusmn090E) coll5 December 1996 by P E Reavell Albany Museum mdash GEN910 one female Mpolozi swampsMapelane (28plusmn2601300S 32plusmn2402500E) coll 13 February 1991 Albany Museum mdash GEN965 twomales ve females NrsquoKoninga Valley Richards Bay (28plusmn450S 32plusmn030E) coll 7 April 1988

Other material mdash The following specimens included in the collections of the South AfricanMuseum warrant further investigation as although they bear some resemblance to the speciesdescribed below their identi cation is uncertain SAM A41276 one male one female Mbonenidam Mkuze Game Reserve (27plusmn3705700S 32plusmn1504500E) coll 28 October 1994 by M Coke SAMA41299 two males Nxwala stream Mkuze Game Reserve (27plusmn4302300S 32plusmn1601000E) coll 10November 1994 by O Bourquin SAM A41277 one male Rainpool south of entrance False BayPark (28plusmn0000100S 32plusmn2102100E) coll 26 October 1994 by M Coke SAM A41300 two malesKangela rainpoolN2 near Mtubatuba (28plusmn2200000S 32plusmn1103600E) coll 25 October 1994 by M Cokeand SAM A41211 one male Ntambanana (Ntrabanana) Zululand coll by H H Curson

Type locality mdash South Africa KwaZulu-Natal Barringtonia and Ficus swampforest next to road 8 km from rest camp Mapelane Nature Reserve (28plusmn2701100S32plusmn2401800E)

Distribution mdash At present known only from the swamp forests (characterizedby Barringtonia racemosa Syzygium cordatum and Ficus trichopoda vegetationand spongy hydromorphic peat-soil) in the vicinity of Richards Bay Empangeniand the Mapelane Nature Reserve It is probable that the distribution of the speciesmay extend into low-lying areas to the east of the Drakensberg escarpment in theprovince of Mpumalanga and into Mozambique

Etymology mdash From the Latin ldquolividusrdquo meaning ldquobluerdquo or ldquolight bluerdquoreferring to the characteristic silver-blue sheen of the carapace The epitheton isan adjective agreeing in gender with the (masculine) generic name

POTAMONAUTES LIVIDUS NOV 153

Fig 6 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A wholeanimal dorsal aspect B whole animal ventral aspect C cephalothorax frontal aspect

Diagnosis mdash Carapace distinctly vaulted and relatively narrow posteriorlyEpibranchial teeth absent and anterolateral margin of the carapace smooth Post-frontal crest indistinct medially with frontal lobe projecting downwards Cara-pace characteristically orange to red with silver-blue sheen Chelipeds and limbs

154 G GOUWS B A STEWART amp P E REAVELL

bright orange to red with lighter cheliped and dactyl tips Chela in ated and highlyarched

Description of male holotype mdash Size Measurements of the holotype and theranges of other specimens are given in table IV

Carapace ( gs 6A C 7A) Carapace and limbs characteristically orange tored with the carapace possessing a silver-blue sheen when alive Preserved spec-imens (70 ethanol) appear less orange and the carapace retains a blue-greycolour Cephalothorax ovoid distinctly vaulted branchial region highly convex( g 6A C) maximum height and width at anterior third (ratio CHCL D 065CWWCL D 145) Anterior margin straight Urogastric grooves moderately wellde ned Cardiac grooves shallow and poorly de ned Carapace otherwise smoothPostfrontal crest smooth curves forward medially Postfrontal crest diminishesabove inner orbit margins though well de ned immediately lateral to forked mid-point groove by means of two indentations anterior to crest indicating epigas-tric lobes Exorbital teeth moderately sharp but small Epibranchial teeth ab-sent Anterolateral margin posterior to postfrontal crest smooth margin curvingin over carapace in branchial region though indistinctly Each ank has a longitu-dinal groove dividing the subhepatic from the pterygostomial region with verticalgroove running from longitudinal groove joining anterolateral margin between ex-orbital tooth and postfrontal crest

Sternites ( gs 6B 7B) Sternites 1 and 2 fused no suture visible First suture(sternal groove) between sternites 2 and 3 complete Second sternal groove

TABLE IVPotamonautes lividus sp nov wet weight (in g) and measurements (in mm) for the male holotype

and ranges for other individuals examined (maximum of 77 males and 70 females)

Variable Abbreviation Holotype Males Females

Wet weight WW 242 05-214 07-183Carapace length CL 255 84-247 89-276Carapace widest width CWW 370 114-360 118-373Carapace posterior width CWP 281 90-269 86-306Distance between postfrontal crest

and anterior margin PFCD 43 12-222 15-46Distance between orbits ED 114 42-119 43-123Distance between exorbital teeth CWA 259 96-254 96-262Carapace height CH 165 48-171 50-162Width of sixth abdominal segment AW6 75 28-74 31-240Major cheliped propodus length MCPL 427 71-402 76-291Major cheliped propodus height MCPH 198 28-189 28-142Pereopod 2 merus length P2ML 189 50-181 51-171Pereopod 2 merus width P2MW 58 19-56 18-59

POTAMONAUTES LIVIDUS NOV 155

Fig 7 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A carapaceoutline B thoracic sternum C right cheliped dactylus and propodus D left cheliped dactylusand propodus E left third maxilliped F left mandible and mandibular palp posterior view G leftmandibular palp posterior view H left mandibular palp anterior view I left gonopod 1 anteriorview J terminal segment left gonopod 1 anterior view K left gonopod 1 posterior view L leftgonopod 2 anterior view Scale lines represent 1 mm except for A-D where they represent 10 mm

156 G GOUWS B A STEWART amp P E REAVELL

between sternites 3 and 4 complete laterally becoming shallower mediallysloping sharply towards abdominopelvic region

Third maxillipeds ( gs 6C 7E) Filling entire buccal frame except for ovalefferent respiratory openings short agellum present on exopods ischium smoothwith moderately deep vertical groove

Mandibular palp ( g 7F G H) Mandibular palp with two segments terminalsegment undivided with a dense tuft of setae on posterior surface of angeof terminal segment Margins generally hirsute Subterminal segment slightlyenlarged distally

Chelipeds and walking legs ( gs 6A 7C D) Chelipeds markedly unequaldactylus of right cheliped strongly arched 163 times length of dactylus of leftcheliped Both dactyli armed with up to 20 cutting teeth three to four of whichare slightly larger and more prominent Propodus of right cheliped markedlyin ated 168 times longer and 20 times wider than that of left cheliped Pollexpossesses 20 cutting teeth four to ve of which are more prominent Carpi ofboth chelipeds possess one prominent and three rudimentary teeth Margins ofmeri granulose small blunt spine on anterior surface no spine on anterior-inferiormargin Pereopods generally slender (pereopod 2 merus length width D 328 andpereopod 5 merus lengthwidth D 271) P3 longest P5 shortest ventral marginsof propodi and meri smooth dorsal margin with ne sharp bristles dactyli endingin sharp points with margins bearing a series of sharp spinelike bristles

Pleon ( gs 6B 7B) First ve segments broad and short last two segmentslonger terminal segment rounded at distal end

Pleopods ( g 7I J K) Pleopod 1 (gonopod 1) terminal segment short 025times length of subterminal segment terminal segment curves away from mid-line when viewed posteriorly widest at base ending in pointed tip Subterminalsegment of pleopod 1 tapers distally inner lateral margin slightly irregular outerlateral margin straighter both margins hirsute Posterior surface with twisting lon-gitudinal groove extending length of subterminal and terminal segment Groovenot visible on anterior surface Posterior surface and margins of groove hirsutePleopod 2 (gonopod 2) terminal segment lament-like 05 the length of subter-minal segment curving slightly towards medial line proximally curves away frommedial line distally ( g 7L) Subterminal segment widest at base tapering sharplyinwards at 04 of length forms narrow process supporting terminal segment

Variation mdash All individuals are characteristically dark orange to red witha silver-blue sheen to the carapace while the chelipeds vary in colour frombright orange-red to a lighter yellow-orange All individuals are characterized byhighly vaulted carapaces and downwardly projecting frontal lobes The postfrontalcrest which is most pronounced laterally (from directly above the orbits to theanterolateral margin) and incomplete medially is often more distinct in the smaller

POTAMONAUTES LIVIDUS NOV 157

individuals Chelipeds are not always typically arched enclosing a large ovoidspace as in the holotype Chelipeds of smaller individuals although in ated areless arched and often tight closing with the small cutting teeth more obviousChelipeds of females and small males in particular from the Mdibi and Universityof Zululand localities have propodi that are relatively high with in ated palmsand relatively short tightly closing chelae which project slightly downwardsHeterochely has been demonstrated in most Potamonautes-species occurring inSouth Africa (Siegfried 1972 Raubenheimer 1986 Stewart et al 1995 Stewart1997a b Stewart amp Cook 1998 Daniels et al 1998a Gouws et al 2000) Withinthe species 76 of the specimens were right-handed with 11 being left-handedand 13 being of equal or subequal (differing by less than one millimeter) sizeOf the males 79 were right-handed 8 left-handed and 13 equal or subequalFemales had 74 right-handedness 13 left-handedness and in 13 of caseschelipeds were equal or subequal The abdomen of mature females completelyoverlaps the coxae of the pereopods The smallest mature female had a CL of167 mm with the largest immature female having a CL of 159 indicating that thepubertal moult occurs approximately between the 14 mm and 18 mm size classes

Remarks mdash Potamonautes lividus sp nov can readily be distinguished from theten other species in the genus Potamonautes known to occur within South AfricaPotamonautes warreni Calman 1918 P dentatus P parvispina and P unispinusall bear a singular spine or a series of teeth on the anterolateral margins whereasP lividus sp nov is smooth Potamonautes perlatus P sidneyi and P granularisare all larger crabs with in ated arched carapaces with complete distinct post-frontal crests and scabrosity or granulation of the anterior margins orbits epi-branchial corners or postfrontal crests Potamonautes lividus sp nov has smoothcarapace margins and a incomplete postfrontal crest The terminal segment ofgonopod 1 in P lividus sp nov is relatively short and triangular and curves awayfrom the medial line when viewed posteriorly while that of P sidneyi is relativelylonger more slender and more S-shaped The postfrontal crest of P sidneyi mayjoin the anterolateral margin at a relatively sharp angle and form a pronouncedepibranchial corner along the anterolateral margin The anterolateral margin inP lividus sp nov is more rounded and the epibranchial corners slope down to-wards the anks Potamonautes granularis is chocolate brown with orange tips tothe chelipeds Potamonautes brincki is a smaller crab with a smoother carapacethough also chocolate to reddish-brown in colour with a nely granulated antero-lateral margin which does not curve in over the carapace in the branchial region(Stewart 1997b) Potamonautes depressus and P clarus both have rounded epi-branchial corners and smooth carapaces though these are relatively shallow andhave attened dorsal surfaces Both are characterized by long slender limbs Pota-monautes depressus is brown to green-brown in colour while P clarus is brightorange in colour

158 G GOUWS B A STEWART amp P E REAVELL

A number of species from further a eld bear a super cial resemblance toP lividus sp nov particularly with regard to carapace morphology though in mostcases they can be readily distinguished Potamonautes pilosus Hilgendorf 1898 isknown from East Africa and is a small crab with a CWW of less than 25 mmSpecimens possess a weak postfrontal crest which along with the anterolateralmargin can be granulated (Hilgendorf 1898 Bott 1955) Potamonautes neumanniHilgendorf 1898 is known from East Africa and has a characteristically vaultedcarapace without a complete distinct postfrontal crest (Hilgendorf 1898 Bott1955) The postfrontal crest is more distinct in P lividus particularly laterally andthe exorbital teeth are sharper and more de ned in P lividus than in P neumanniThe terminal segment of gonopod 1 is longer and more slender in P neumannithan in P lividus and curves distinctly outwards The subterminal segment ofgonopod 1 is wider at its apex in P neumanni than in P lividus Additionally thecarapace of preserved specimens of P neumanni is typically grey in colour whileliving specimens are violet in colour with bright olive-green limbs and chelipeds(Hilgendorf 1898) Potamonautes ballayi acristatus Bott 1955 has an incompletepostfrontal crest only present above the orbits and small and blunt exorbital teethThe major chela although highly arched and the minor chela are long and moreslender than those of P lividus sp nov The terminal segment of gonopod 1 ofP granviki Colosi 1924 is curved towards the medial line when viewed posteriorly(Bott 1955) The chelae of both P berardi berardi Audouin 1826 and P b ignestiiParisi 1923 are relatively short and high with stout downward-projecting ngersThe anterior margin of the frontal lobe of P b berardi shows a distinct invaginationand the anterolateral margin appears sharp and less rounded than in P lividus spnov while the postfrontal crest of P b ignestii is complete and has a fairly longmedial groove Potamonautes emini emini Hilgendorf 1892 are generally smallcrabs with a less in ated carapace and short stout chelipeds The subterminaland terminal segments of gonopod 1 are of more or less equal size (Bott 1955)Potamonautes e semilunaris Bott 1955 and P luashiensis Bott 1955 are alsosmall crabs (CWW lt 20 mm) with the postfrontal crest only visible laterally andin the case of P luashiensis the anterolateral margin and postfrontal crest mayshow granulation Potamonautes didieri Rathbun 1904 possesses a more completerounded postfrontal crest and shorter more stout chelipeds (Bott 1955)

ACKNOWLEDGEMENTS

Financial assistance was kindly provided by the World Wildlife Fund - SouthAfrica the Foundation for Research Development and the University of ZululandThe KwaZulu-Natal Nature Conservation Services provided accommodation and

POTAMONAUTES LIVIDUS NOV 159

logistic support Liz Hoenson Peter Cook Mike Coke and Tyrone Ridgway arethanked for assistance in the eld and Michelle van der Merwe is thanked foraiding in the photography and drafting of gures The authors wish to thank ananonymous reviewer for comments on the manuscript

REFERENCES

BARNARD K H 1935 Scienti c results of the Vernay-Lang Kalahari expedition March toSeptember 1930 Crustacea Ann Transvaal Mus 16 481-492

mdash mdash 1950 Descriptive catalogue of South African decapod Crustacea (crabs and shrimps) AnnSouth African Mus 38 1-837

BOCK W J 1986 Species concepts speciation and macroevolution In K IWATSUKIP H RAVEN amp W J BOCK (eds) Modern aspects of species 31-57 (University of TokyoPress Tokyo)

BOTT R 1955 Die Suumlsswasserkrabben von Afrika (Crust Decap) und ihre StammesgeschichteAnn Mus R Congo Belge (C Zool) 1 (33) 209-352 pls 1-30

BRUTON M N 1980 An outline of the ecology of the Mgobezeleni lake system at Sodwana withemphasis on the mangrove community In M N BRUTON amp K H COOPER (eds) Studieson the ecology of Maputaland 408-426 (Rhodes University Grahamstown)

CUMBERLIDGE N 1986 Ventilation of the branchial chambers in the amphibious West Africanfreshwater crab Sudanonautes (Convexonautes) aubryi monodi (Balss 1929) (BrachyuraPotamonautidae)Hydrobiol 134 53-65

mdash mdash 1991 The respiratory system of Globonautes macropus (Rathbun 1898) a terrestrialfreshwater crab from Liberia (GecarcinucoideaGecarcinucidae)Crustaceana 61 (1) 69-80

DANIELS S R B A STEWART amp M J GIBBONS 1998a Potamonautes granularis sp nov(Brachyura Potamonautidae) a new cryptic species of river crab from the Olifants Riversystem South Africa Crustaceana 71 (8) 885-903

mdash mdash mdash mdash amp mdash mdash 1998b Genetic and morphometric variation in the potamonautid river crabPotamonautes parvispina (Decapoda Potamonautidae) from two Western Cape rivers SouthAfrica Journ nat Hist London 32 1245-1258

mdash mdash mdash mdash amp mdash mdash 1999 Genetic structure among populations of Potamonautes perlatus(Decapoda Potamonautidae) from the Olifants River system in the Western Cape SouthAfrica Journ Zool London 249 (2) 137-142

DIacuteAZ H amp G RODRIacuteGUEZ 1977 The branchial chamber in terrestrial crabs a comparative studyBiol Bull Woods Hole 153 485-504

GOUWS G B A STEWART amp M COKE 2000 Evidence for a new species of river crab(Decapoda Brachyura Potamonautidae) from the Drakensberg South Africa Journ CrustBiol 20 (4) 743-758

GREENAWAY P amp H H TAYLOR 1976 Aerial gas exchange in Australian arid-zone crabParathelphusa transversa Von Martens Nature London 262 711-713

HILGENDORF F 1898 Die Land- und Suumlsswasser-Dekapoden Ostafrikas Die Thierwelt DeutschOst-Afrikas 4 (7) 1-37

LENZ H 1912 Afrikanische Crustaceen aus schwedischen Sammlungen Ark Zool 7 (29) 1-10MARKERT C L amp I FAULHABER 1965 Lactate dehydrogenase isozyme patterns of sh Journ

exp Zool 159 319-332MAYR E 1963 Animal species and evolution i-xiv 1-797 (Harvard University Press Cambridge

Massachusetts)mdash mdash 1970 Populations species and evolution i-xv 1-453 (Harvard University Press Cambridge

Massachusetts)

POTAMONAUTES LIVIDUS NOV 153

Fig 6 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A wholeanimal dorsal aspect B whole animal ventral aspect C cephalothorax frontal aspect

Diagnosis mdash Carapace distinctly vaulted and relatively narrow posteriorlyEpibranchial teeth absent and anterolateral margin of the carapace smooth Post-frontal crest indistinct medially with frontal lobe projecting downwards Cara-pace characteristically orange to red with silver-blue sheen Chelipeds and limbs

154 G GOUWS B A STEWART amp P E REAVELL

bright orange to red with lighter cheliped and dactyl tips Chela in ated and highlyarched

Description of male holotype mdash Size Measurements of the holotype and theranges of other specimens are given in table IV

Carapace ( gs 6A C 7A) Carapace and limbs characteristically orange tored with the carapace possessing a silver-blue sheen when alive Preserved spec-imens (70 ethanol) appear less orange and the carapace retains a blue-greycolour Cephalothorax ovoid distinctly vaulted branchial region highly convex( g 6A C) maximum height and width at anterior third (ratio CHCL D 065CWWCL D 145) Anterior margin straight Urogastric grooves moderately wellde ned Cardiac grooves shallow and poorly de ned Carapace otherwise smoothPostfrontal crest smooth curves forward medially Postfrontal crest diminishesabove inner orbit margins though well de ned immediately lateral to forked mid-point groove by means of two indentations anterior to crest indicating epigas-tric lobes Exorbital teeth moderately sharp but small Epibranchial teeth ab-sent Anterolateral margin posterior to postfrontal crest smooth margin curvingin over carapace in branchial region though indistinctly Each ank has a longitu-dinal groove dividing the subhepatic from the pterygostomial region with verticalgroove running from longitudinal groove joining anterolateral margin between ex-orbital tooth and postfrontal crest

Sternites ( gs 6B 7B) Sternites 1 and 2 fused no suture visible First suture(sternal groove) between sternites 2 and 3 complete Second sternal groove

TABLE IVPotamonautes lividus sp nov wet weight (in g) and measurements (in mm) for the male holotype

and ranges for other individuals examined (maximum of 77 males and 70 females)

Variable Abbreviation Holotype Males Females

Wet weight WW 242 05-214 07-183Carapace length CL 255 84-247 89-276Carapace widest width CWW 370 114-360 118-373Carapace posterior width CWP 281 90-269 86-306Distance between postfrontal crest

and anterior margin PFCD 43 12-222 15-46Distance between orbits ED 114 42-119 43-123Distance between exorbital teeth CWA 259 96-254 96-262Carapace height CH 165 48-171 50-162Width of sixth abdominal segment AW6 75 28-74 31-240Major cheliped propodus length MCPL 427 71-402 76-291Major cheliped propodus height MCPH 198 28-189 28-142Pereopod 2 merus length P2ML 189 50-181 51-171Pereopod 2 merus width P2MW 58 19-56 18-59

POTAMONAUTES LIVIDUS NOV 155

Fig 7 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A carapaceoutline B thoracic sternum C right cheliped dactylus and propodus D left cheliped dactylusand propodus E left third maxilliped F left mandible and mandibular palp posterior view G leftmandibular palp posterior view H left mandibular palp anterior view I left gonopod 1 anteriorview J terminal segment left gonopod 1 anterior view K left gonopod 1 posterior view L leftgonopod 2 anterior view Scale lines represent 1 mm except for A-D where they represent 10 mm

156 G GOUWS B A STEWART amp P E REAVELL

between sternites 3 and 4 complete laterally becoming shallower mediallysloping sharply towards abdominopelvic region

Third maxillipeds ( gs 6C 7E) Filling entire buccal frame except for ovalefferent respiratory openings short agellum present on exopods ischium smoothwith moderately deep vertical groove

Mandibular palp ( g 7F G H) Mandibular palp with two segments terminalsegment undivided with a dense tuft of setae on posterior surface of angeof terminal segment Margins generally hirsute Subterminal segment slightlyenlarged distally

Chelipeds and walking legs ( gs 6A 7C D) Chelipeds markedly unequaldactylus of right cheliped strongly arched 163 times length of dactylus of leftcheliped Both dactyli armed with up to 20 cutting teeth three to four of whichare slightly larger and more prominent Propodus of right cheliped markedlyin ated 168 times longer and 20 times wider than that of left cheliped Pollexpossesses 20 cutting teeth four to ve of which are more prominent Carpi ofboth chelipeds possess one prominent and three rudimentary teeth Margins ofmeri granulose small blunt spine on anterior surface no spine on anterior-inferiormargin Pereopods generally slender (pereopod 2 merus length width D 328 andpereopod 5 merus lengthwidth D 271) P3 longest P5 shortest ventral marginsof propodi and meri smooth dorsal margin with ne sharp bristles dactyli endingin sharp points with margins bearing a series of sharp spinelike bristles

Pleon ( gs 6B 7B) First ve segments broad and short last two segmentslonger terminal segment rounded at distal end

Pleopods ( g 7I J K) Pleopod 1 (gonopod 1) terminal segment short 025times length of subterminal segment terminal segment curves away from mid-line when viewed posteriorly widest at base ending in pointed tip Subterminalsegment of pleopod 1 tapers distally inner lateral margin slightly irregular outerlateral margin straighter both margins hirsute Posterior surface with twisting lon-gitudinal groove extending length of subterminal and terminal segment Groovenot visible on anterior surface Posterior surface and margins of groove hirsutePleopod 2 (gonopod 2) terminal segment lament-like 05 the length of subter-minal segment curving slightly towards medial line proximally curves away frommedial line distally ( g 7L) Subterminal segment widest at base tapering sharplyinwards at 04 of length forms narrow process supporting terminal segment

Variation mdash All individuals are characteristically dark orange to red witha silver-blue sheen to the carapace while the chelipeds vary in colour frombright orange-red to a lighter yellow-orange All individuals are characterized byhighly vaulted carapaces and downwardly projecting frontal lobes The postfrontalcrest which is most pronounced laterally (from directly above the orbits to theanterolateral margin) and incomplete medially is often more distinct in the smaller

POTAMONAUTES LIVIDUS NOV 157

individuals Chelipeds are not always typically arched enclosing a large ovoidspace as in the holotype Chelipeds of smaller individuals although in ated areless arched and often tight closing with the small cutting teeth more obviousChelipeds of females and small males in particular from the Mdibi and Universityof Zululand localities have propodi that are relatively high with in ated palmsand relatively short tightly closing chelae which project slightly downwardsHeterochely has been demonstrated in most Potamonautes-species occurring inSouth Africa (Siegfried 1972 Raubenheimer 1986 Stewart et al 1995 Stewart1997a b Stewart amp Cook 1998 Daniels et al 1998a Gouws et al 2000) Withinthe species 76 of the specimens were right-handed with 11 being left-handedand 13 being of equal or subequal (differing by less than one millimeter) sizeOf the males 79 were right-handed 8 left-handed and 13 equal or subequalFemales had 74 right-handedness 13 left-handedness and in 13 of caseschelipeds were equal or subequal The abdomen of mature females completelyoverlaps the coxae of the pereopods The smallest mature female had a CL of167 mm with the largest immature female having a CL of 159 indicating that thepubertal moult occurs approximately between the 14 mm and 18 mm size classes

Remarks mdash Potamonautes lividus sp nov can readily be distinguished from theten other species in the genus Potamonautes known to occur within South AfricaPotamonautes warreni Calman 1918 P dentatus P parvispina and P unispinusall bear a singular spine or a series of teeth on the anterolateral margins whereasP lividus sp nov is smooth Potamonautes perlatus P sidneyi and P granularisare all larger crabs with in ated arched carapaces with complete distinct post-frontal crests and scabrosity or granulation of the anterior margins orbits epi-branchial corners or postfrontal crests Potamonautes lividus sp nov has smoothcarapace margins and a incomplete postfrontal crest The terminal segment ofgonopod 1 in P lividus sp nov is relatively short and triangular and curves awayfrom the medial line when viewed posteriorly while that of P sidneyi is relativelylonger more slender and more S-shaped The postfrontal crest of P sidneyi mayjoin the anterolateral margin at a relatively sharp angle and form a pronouncedepibranchial corner along the anterolateral margin The anterolateral margin inP lividus sp nov is more rounded and the epibranchial corners slope down to-wards the anks Potamonautes granularis is chocolate brown with orange tips tothe chelipeds Potamonautes brincki is a smaller crab with a smoother carapacethough also chocolate to reddish-brown in colour with a nely granulated antero-lateral margin which does not curve in over the carapace in the branchial region(Stewart 1997b) Potamonautes depressus and P clarus both have rounded epi-branchial corners and smooth carapaces though these are relatively shallow andhave attened dorsal surfaces Both are characterized by long slender limbs Pota-monautes depressus is brown to green-brown in colour while P clarus is brightorange in colour

158 G GOUWS B A STEWART amp P E REAVELL

A number of species from further a eld bear a super cial resemblance toP lividus sp nov particularly with regard to carapace morphology though in mostcases they can be readily distinguished Potamonautes pilosus Hilgendorf 1898 isknown from East Africa and is a small crab with a CWW of less than 25 mmSpecimens possess a weak postfrontal crest which along with the anterolateralmargin can be granulated (Hilgendorf 1898 Bott 1955) Potamonautes neumanniHilgendorf 1898 is known from East Africa and has a characteristically vaultedcarapace without a complete distinct postfrontal crest (Hilgendorf 1898 Bott1955) The postfrontal crest is more distinct in P lividus particularly laterally andthe exorbital teeth are sharper and more de ned in P lividus than in P neumanniThe terminal segment of gonopod 1 is longer and more slender in P neumannithan in P lividus and curves distinctly outwards The subterminal segment ofgonopod 1 is wider at its apex in P neumanni than in P lividus Additionally thecarapace of preserved specimens of P neumanni is typically grey in colour whileliving specimens are violet in colour with bright olive-green limbs and chelipeds(Hilgendorf 1898) Potamonautes ballayi acristatus Bott 1955 has an incompletepostfrontal crest only present above the orbits and small and blunt exorbital teethThe major chela although highly arched and the minor chela are long and moreslender than those of P lividus sp nov The terminal segment of gonopod 1 ofP granviki Colosi 1924 is curved towards the medial line when viewed posteriorly(Bott 1955) The chelae of both P berardi berardi Audouin 1826 and P b ignestiiParisi 1923 are relatively short and high with stout downward-projecting ngersThe anterior margin of the frontal lobe of P b berardi shows a distinct invaginationand the anterolateral margin appears sharp and less rounded than in P lividus spnov while the postfrontal crest of P b ignestii is complete and has a fairly longmedial groove Potamonautes emini emini Hilgendorf 1892 are generally smallcrabs with a less in ated carapace and short stout chelipeds The subterminaland terminal segments of gonopod 1 are of more or less equal size (Bott 1955)Potamonautes e semilunaris Bott 1955 and P luashiensis Bott 1955 are alsosmall crabs (CWW lt 20 mm) with the postfrontal crest only visible laterally andin the case of P luashiensis the anterolateral margin and postfrontal crest mayshow granulation Potamonautes didieri Rathbun 1904 possesses a more completerounded postfrontal crest and shorter more stout chelipeds (Bott 1955)

ACKNOWLEDGEMENTS

Financial assistance was kindly provided by the World Wildlife Fund - SouthAfrica the Foundation for Research Development and the University of ZululandThe KwaZulu-Natal Nature Conservation Services provided accommodation and

POTAMONAUTES LIVIDUS NOV 159

logistic support Liz Hoenson Peter Cook Mike Coke and Tyrone Ridgway arethanked for assistance in the eld and Michelle van der Merwe is thanked foraiding in the photography and drafting of gures The authors wish to thank ananonymous reviewer for comments on the manuscript

REFERENCES

BARNARD K H 1935 Scienti c results of the Vernay-Lang Kalahari expedition March toSeptember 1930 Crustacea Ann Transvaal Mus 16 481-492

mdash mdash 1950 Descriptive catalogue of South African decapod Crustacea (crabs and shrimps) AnnSouth African Mus 38 1-837

BOCK W J 1986 Species concepts speciation and macroevolution In K IWATSUKIP H RAVEN amp W J BOCK (eds) Modern aspects of species 31-57 (University of TokyoPress Tokyo)

BOTT R 1955 Die Suumlsswasserkrabben von Afrika (Crust Decap) und ihre StammesgeschichteAnn Mus R Congo Belge (C Zool) 1 (33) 209-352 pls 1-30

BRUTON M N 1980 An outline of the ecology of the Mgobezeleni lake system at Sodwana withemphasis on the mangrove community In M N BRUTON amp K H COOPER (eds) Studieson the ecology of Maputaland 408-426 (Rhodes University Grahamstown)

CUMBERLIDGE N 1986 Ventilation of the branchial chambers in the amphibious West Africanfreshwater crab Sudanonautes (Convexonautes) aubryi monodi (Balss 1929) (BrachyuraPotamonautidae)Hydrobiol 134 53-65

mdash mdash 1991 The respiratory system of Globonautes macropus (Rathbun 1898) a terrestrialfreshwater crab from Liberia (GecarcinucoideaGecarcinucidae)Crustaceana 61 (1) 69-80

DANIELS S R B A STEWART amp M J GIBBONS 1998a Potamonautes granularis sp nov(Brachyura Potamonautidae) a new cryptic species of river crab from the Olifants Riversystem South Africa Crustaceana 71 (8) 885-903

mdash mdash mdash mdash amp mdash mdash 1998b Genetic and morphometric variation in the potamonautid river crabPotamonautes parvispina (Decapoda Potamonautidae) from two Western Cape rivers SouthAfrica Journ nat Hist London 32 1245-1258

mdash mdash mdash mdash amp mdash mdash 1999 Genetic structure among populations of Potamonautes perlatus(Decapoda Potamonautidae) from the Olifants River system in the Western Cape SouthAfrica Journ Zool London 249 (2) 137-142

DIacuteAZ H amp G RODRIacuteGUEZ 1977 The branchial chamber in terrestrial crabs a comparative studyBiol Bull Woods Hole 153 485-504

GOUWS G B A STEWART amp M COKE 2000 Evidence for a new species of river crab(Decapoda Brachyura Potamonautidae) from the Drakensberg South Africa Journ CrustBiol 20 (4) 743-758

GREENAWAY P amp H H TAYLOR 1976 Aerial gas exchange in Australian arid-zone crabParathelphusa transversa Von Martens Nature London 262 711-713

HILGENDORF F 1898 Die Land- und Suumlsswasser-Dekapoden Ostafrikas Die Thierwelt DeutschOst-Afrikas 4 (7) 1-37

LENZ H 1912 Afrikanische Crustaceen aus schwedischen Sammlungen Ark Zool 7 (29) 1-10MARKERT C L amp I FAULHABER 1965 Lactate dehydrogenase isozyme patterns of sh Journ

exp Zool 159 319-332MAYR E 1963 Animal species and evolution i-xiv 1-797 (Harvard University Press Cambridge

Massachusetts)mdash mdash 1970 Populations species and evolution i-xv 1-453 (Harvard University Press Cambridge

Massachusetts)

154 G GOUWS B A STEWART amp P E REAVELL

bright orange to red with lighter cheliped and dactyl tips Chela in ated and highlyarched

Description of male holotype mdash Size Measurements of the holotype and theranges of other specimens are given in table IV

Carapace ( gs 6A C 7A) Carapace and limbs characteristically orange tored with the carapace possessing a silver-blue sheen when alive Preserved spec-imens (70 ethanol) appear less orange and the carapace retains a blue-greycolour Cephalothorax ovoid distinctly vaulted branchial region highly convex( g 6A C) maximum height and width at anterior third (ratio CHCL D 065CWWCL D 145) Anterior margin straight Urogastric grooves moderately wellde ned Cardiac grooves shallow and poorly de ned Carapace otherwise smoothPostfrontal crest smooth curves forward medially Postfrontal crest diminishesabove inner orbit margins though well de ned immediately lateral to forked mid-point groove by means of two indentations anterior to crest indicating epigas-tric lobes Exorbital teeth moderately sharp but small Epibranchial teeth ab-sent Anterolateral margin posterior to postfrontal crest smooth margin curvingin over carapace in branchial region though indistinctly Each ank has a longitu-dinal groove dividing the subhepatic from the pterygostomial region with verticalgroove running from longitudinal groove joining anterolateral margin between ex-orbital tooth and postfrontal crest

Sternites ( gs 6B 7B) Sternites 1 and 2 fused no suture visible First suture(sternal groove) between sternites 2 and 3 complete Second sternal groove

TABLE IVPotamonautes lividus sp nov wet weight (in g) and measurements (in mm) for the male holotype

and ranges for other individuals examined (maximum of 77 males and 70 females)

Variable Abbreviation Holotype Males Females

Wet weight WW 242 05-214 07-183Carapace length CL 255 84-247 89-276Carapace widest width CWW 370 114-360 118-373Carapace posterior width CWP 281 90-269 86-306Distance between postfrontal crest

and anterior margin PFCD 43 12-222 15-46Distance between orbits ED 114 42-119 43-123Distance between exorbital teeth CWA 259 96-254 96-262Carapace height CH 165 48-171 50-162Width of sixth abdominal segment AW6 75 28-74 31-240Major cheliped propodus length MCPL 427 71-402 76-291Major cheliped propodus height MCPH 198 28-189 28-142Pereopod 2 merus length P2ML 189 50-181 51-171Pereopod 2 merus width P2MW 58 19-56 18-59

POTAMONAUTES LIVIDUS NOV 155

Fig 7 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A carapaceoutline B thoracic sternum C right cheliped dactylus and propodus D left cheliped dactylusand propodus E left third maxilliped F left mandible and mandibular palp posterior view G leftmandibular palp posterior view H left mandibular palp anterior view I left gonopod 1 anteriorview J terminal segment left gonopod 1 anterior view K left gonopod 1 posterior view L leftgonopod 2 anterior view Scale lines represent 1 mm except for A-D where they represent 10 mm

156 G GOUWS B A STEWART amp P E REAVELL

between sternites 3 and 4 complete laterally becoming shallower mediallysloping sharply towards abdominopelvic region

Third maxillipeds ( gs 6C 7E) Filling entire buccal frame except for ovalefferent respiratory openings short agellum present on exopods ischium smoothwith moderately deep vertical groove

Mandibular palp ( g 7F G H) Mandibular palp with two segments terminalsegment undivided with a dense tuft of setae on posterior surface of angeof terminal segment Margins generally hirsute Subterminal segment slightlyenlarged distally

Chelipeds and walking legs ( gs 6A 7C D) Chelipeds markedly unequaldactylus of right cheliped strongly arched 163 times length of dactylus of leftcheliped Both dactyli armed with up to 20 cutting teeth three to four of whichare slightly larger and more prominent Propodus of right cheliped markedlyin ated 168 times longer and 20 times wider than that of left cheliped Pollexpossesses 20 cutting teeth four to ve of which are more prominent Carpi ofboth chelipeds possess one prominent and three rudimentary teeth Margins ofmeri granulose small blunt spine on anterior surface no spine on anterior-inferiormargin Pereopods generally slender (pereopod 2 merus length width D 328 andpereopod 5 merus lengthwidth D 271) P3 longest P5 shortest ventral marginsof propodi and meri smooth dorsal margin with ne sharp bristles dactyli endingin sharp points with margins bearing a series of sharp spinelike bristles

Pleon ( gs 6B 7B) First ve segments broad and short last two segmentslonger terminal segment rounded at distal end

Pleopods ( g 7I J K) Pleopod 1 (gonopod 1) terminal segment short 025times length of subterminal segment terminal segment curves away from mid-line when viewed posteriorly widest at base ending in pointed tip Subterminalsegment of pleopod 1 tapers distally inner lateral margin slightly irregular outerlateral margin straighter both margins hirsute Posterior surface with twisting lon-gitudinal groove extending length of subterminal and terminal segment Groovenot visible on anterior surface Posterior surface and margins of groove hirsutePleopod 2 (gonopod 2) terminal segment lament-like 05 the length of subter-minal segment curving slightly towards medial line proximally curves away frommedial line distally ( g 7L) Subterminal segment widest at base tapering sharplyinwards at 04 of length forms narrow process supporting terminal segment

Variation mdash All individuals are characteristically dark orange to red witha silver-blue sheen to the carapace while the chelipeds vary in colour frombright orange-red to a lighter yellow-orange All individuals are characterized byhighly vaulted carapaces and downwardly projecting frontal lobes The postfrontalcrest which is most pronounced laterally (from directly above the orbits to theanterolateral margin) and incomplete medially is often more distinct in the smaller

POTAMONAUTES LIVIDUS NOV 157

individuals Chelipeds are not always typically arched enclosing a large ovoidspace as in the holotype Chelipeds of smaller individuals although in ated areless arched and often tight closing with the small cutting teeth more obviousChelipeds of females and small males in particular from the Mdibi and Universityof Zululand localities have propodi that are relatively high with in ated palmsand relatively short tightly closing chelae which project slightly downwardsHeterochely has been demonstrated in most Potamonautes-species occurring inSouth Africa (Siegfried 1972 Raubenheimer 1986 Stewart et al 1995 Stewart1997a b Stewart amp Cook 1998 Daniels et al 1998a Gouws et al 2000) Withinthe species 76 of the specimens were right-handed with 11 being left-handedand 13 being of equal or subequal (differing by less than one millimeter) sizeOf the males 79 were right-handed 8 left-handed and 13 equal or subequalFemales had 74 right-handedness 13 left-handedness and in 13 of caseschelipeds were equal or subequal The abdomen of mature females completelyoverlaps the coxae of the pereopods The smallest mature female had a CL of167 mm with the largest immature female having a CL of 159 indicating that thepubertal moult occurs approximately between the 14 mm and 18 mm size classes

Remarks mdash Potamonautes lividus sp nov can readily be distinguished from theten other species in the genus Potamonautes known to occur within South AfricaPotamonautes warreni Calman 1918 P dentatus P parvispina and P unispinusall bear a singular spine or a series of teeth on the anterolateral margins whereasP lividus sp nov is smooth Potamonautes perlatus P sidneyi and P granularisare all larger crabs with in ated arched carapaces with complete distinct post-frontal crests and scabrosity or granulation of the anterior margins orbits epi-branchial corners or postfrontal crests Potamonautes lividus sp nov has smoothcarapace margins and a incomplete postfrontal crest The terminal segment ofgonopod 1 in P lividus sp nov is relatively short and triangular and curves awayfrom the medial line when viewed posteriorly while that of P sidneyi is relativelylonger more slender and more S-shaped The postfrontal crest of P sidneyi mayjoin the anterolateral margin at a relatively sharp angle and form a pronouncedepibranchial corner along the anterolateral margin The anterolateral margin inP lividus sp nov is more rounded and the epibranchial corners slope down to-wards the anks Potamonautes granularis is chocolate brown with orange tips tothe chelipeds Potamonautes brincki is a smaller crab with a smoother carapacethough also chocolate to reddish-brown in colour with a nely granulated antero-lateral margin which does not curve in over the carapace in the branchial region(Stewart 1997b) Potamonautes depressus and P clarus both have rounded epi-branchial corners and smooth carapaces though these are relatively shallow andhave attened dorsal surfaces Both are characterized by long slender limbs Pota-monautes depressus is brown to green-brown in colour while P clarus is brightorange in colour

158 G GOUWS B A STEWART amp P E REAVELL

A number of species from further a eld bear a super cial resemblance toP lividus sp nov particularly with regard to carapace morphology though in mostcases they can be readily distinguished Potamonautes pilosus Hilgendorf 1898 isknown from East Africa and is a small crab with a CWW of less than 25 mmSpecimens possess a weak postfrontal crest which along with the anterolateralmargin can be granulated (Hilgendorf 1898 Bott 1955) Potamonautes neumanniHilgendorf 1898 is known from East Africa and has a characteristically vaultedcarapace without a complete distinct postfrontal crest (Hilgendorf 1898 Bott1955) The postfrontal crest is more distinct in P lividus particularly laterally andthe exorbital teeth are sharper and more de ned in P lividus than in P neumanniThe terminal segment of gonopod 1 is longer and more slender in P neumannithan in P lividus and curves distinctly outwards The subterminal segment ofgonopod 1 is wider at its apex in P neumanni than in P lividus Additionally thecarapace of preserved specimens of P neumanni is typically grey in colour whileliving specimens are violet in colour with bright olive-green limbs and chelipeds(Hilgendorf 1898) Potamonautes ballayi acristatus Bott 1955 has an incompletepostfrontal crest only present above the orbits and small and blunt exorbital teethThe major chela although highly arched and the minor chela are long and moreslender than those of P lividus sp nov The terminal segment of gonopod 1 ofP granviki Colosi 1924 is curved towards the medial line when viewed posteriorly(Bott 1955) The chelae of both P berardi berardi Audouin 1826 and P b ignestiiParisi 1923 are relatively short and high with stout downward-projecting ngersThe anterior margin of the frontal lobe of P b berardi shows a distinct invaginationand the anterolateral margin appears sharp and less rounded than in P lividus spnov while the postfrontal crest of P b ignestii is complete and has a fairly longmedial groove Potamonautes emini emini Hilgendorf 1892 are generally smallcrabs with a less in ated carapace and short stout chelipeds The subterminaland terminal segments of gonopod 1 are of more or less equal size (Bott 1955)Potamonautes e semilunaris Bott 1955 and P luashiensis Bott 1955 are alsosmall crabs (CWW lt 20 mm) with the postfrontal crest only visible laterally andin the case of P luashiensis the anterolateral margin and postfrontal crest mayshow granulation Potamonautes didieri Rathbun 1904 possesses a more completerounded postfrontal crest and shorter more stout chelipeds (Bott 1955)

ACKNOWLEDGEMENTS

Financial assistance was kindly provided by the World Wildlife Fund - SouthAfrica the Foundation for Research Development and the University of ZululandThe KwaZulu-Natal Nature Conservation Services provided accommodation and

POTAMONAUTES LIVIDUS NOV 159

logistic support Liz Hoenson Peter Cook Mike Coke and Tyrone Ridgway arethanked for assistance in the eld and Michelle van der Merwe is thanked foraiding in the photography and drafting of gures The authors wish to thank ananonymous reviewer for comments on the manuscript

REFERENCES

BARNARD K H 1935 Scienti c results of the Vernay-Lang Kalahari expedition March toSeptember 1930 Crustacea Ann Transvaal Mus 16 481-492

mdash mdash 1950 Descriptive catalogue of South African decapod Crustacea (crabs and shrimps) AnnSouth African Mus 38 1-837

BOCK W J 1986 Species concepts speciation and macroevolution In K IWATSUKIP H RAVEN amp W J BOCK (eds) Modern aspects of species 31-57 (University of TokyoPress Tokyo)

BOTT R 1955 Die Suumlsswasserkrabben von Afrika (Crust Decap) und ihre StammesgeschichteAnn Mus R Congo Belge (C Zool) 1 (33) 209-352 pls 1-30

BRUTON M N 1980 An outline of the ecology of the Mgobezeleni lake system at Sodwana withemphasis on the mangrove community In M N BRUTON amp K H COOPER (eds) Studieson the ecology of Maputaland 408-426 (Rhodes University Grahamstown)

CUMBERLIDGE N 1986 Ventilation of the branchial chambers in the amphibious West Africanfreshwater crab Sudanonautes (Convexonautes) aubryi monodi (Balss 1929) (BrachyuraPotamonautidae)Hydrobiol 134 53-65

mdash mdash 1991 The respiratory system of Globonautes macropus (Rathbun 1898) a terrestrialfreshwater crab from Liberia (GecarcinucoideaGecarcinucidae)Crustaceana 61 (1) 69-80

DANIELS S R B A STEWART amp M J GIBBONS 1998a Potamonautes granularis sp nov(Brachyura Potamonautidae) a new cryptic species of river crab from the Olifants Riversystem South Africa Crustaceana 71 (8) 885-903

mdash mdash mdash mdash amp mdash mdash 1998b Genetic and morphometric variation in the potamonautid river crabPotamonautes parvispina (Decapoda Potamonautidae) from two Western Cape rivers SouthAfrica Journ nat Hist London 32 1245-1258

mdash mdash mdash mdash amp mdash mdash 1999 Genetic structure among populations of Potamonautes perlatus(Decapoda Potamonautidae) from the Olifants River system in the Western Cape SouthAfrica Journ Zool London 249 (2) 137-142

DIacuteAZ H amp G RODRIacuteGUEZ 1977 The branchial chamber in terrestrial crabs a comparative studyBiol Bull Woods Hole 153 485-504

GOUWS G B A STEWART amp M COKE 2000 Evidence for a new species of river crab(Decapoda Brachyura Potamonautidae) from the Drakensberg South Africa Journ CrustBiol 20 (4) 743-758

GREENAWAY P amp H H TAYLOR 1976 Aerial gas exchange in Australian arid-zone crabParathelphusa transversa Von Martens Nature London 262 711-713

HILGENDORF F 1898 Die Land- und Suumlsswasser-Dekapoden Ostafrikas Die Thierwelt DeutschOst-Afrikas 4 (7) 1-37

LENZ H 1912 Afrikanische Crustaceen aus schwedischen Sammlungen Ark Zool 7 (29) 1-10MARKERT C L amp I FAULHABER 1965 Lactate dehydrogenase isozyme patterns of sh Journ

exp Zool 159 319-332MAYR E 1963 Animal species and evolution i-xiv 1-797 (Harvard University Press Cambridge

Massachusetts)mdash mdash 1970 Populations species and evolution i-xv 1-453 (Harvard University Press Cambridge

Massachusetts)

POTAMONAUTES LIVIDUS NOV 155

Fig 7 Potamonautes lividus sp nov male holotype (CL D 255 mm) SAM A43540 A carapaceoutline B thoracic sternum C right cheliped dactylus and propodus D left cheliped dactylusand propodus E left third maxilliped F left mandible and mandibular palp posterior view G leftmandibular palp posterior view H left mandibular palp anterior view I left gonopod 1 anteriorview J terminal segment left gonopod 1 anterior view K left gonopod 1 posterior view L leftgonopod 2 anterior view Scale lines represent 1 mm except for A-D where they represent 10 mm

156 G GOUWS B A STEWART amp P E REAVELL

between sternites 3 and 4 complete laterally becoming shallower mediallysloping sharply towards abdominopelvic region

Third maxillipeds ( gs 6C 7E) Filling entire buccal frame except for ovalefferent respiratory openings short agellum present on exopods ischium smoothwith moderately deep vertical groove

Mandibular palp ( g 7F G H) Mandibular palp with two segments terminalsegment undivided with a dense tuft of setae on posterior surface of angeof terminal segment Margins generally hirsute Subterminal segment slightlyenlarged distally

Chelipeds and walking legs ( gs 6A 7C D) Chelipeds markedly unequaldactylus of right cheliped strongly arched 163 times length of dactylus of leftcheliped Both dactyli armed with up to 20 cutting teeth three to four of whichare slightly larger and more prominent Propodus of right cheliped markedlyin ated 168 times longer and 20 times wider than that of left cheliped Pollexpossesses 20 cutting teeth four to ve of which are more prominent Carpi ofboth chelipeds possess one prominent and three rudimentary teeth Margins ofmeri granulose small blunt spine on anterior surface no spine on anterior-inferiormargin Pereopods generally slender (pereopod 2 merus length width D 328 andpereopod 5 merus lengthwidth D 271) P3 longest P5 shortest ventral marginsof propodi and meri smooth dorsal margin with ne sharp bristles dactyli endingin sharp points with margins bearing a series of sharp spinelike bristles

Pleon ( gs 6B 7B) First ve segments broad and short last two segmentslonger terminal segment rounded at distal end

Pleopods ( g 7I J K) Pleopod 1 (gonopod 1) terminal segment short 025times length of subterminal segment terminal segment curves away from mid-line when viewed posteriorly widest at base ending in pointed tip Subterminalsegment of pleopod 1 tapers distally inner lateral margin slightly irregular outerlateral margin straighter both margins hirsute Posterior surface with twisting lon-gitudinal groove extending length of subterminal and terminal segment Groovenot visible on anterior surface Posterior surface and margins of groove hirsutePleopod 2 (gonopod 2) terminal segment lament-like 05 the length of subter-minal segment curving slightly towards medial line proximally curves away frommedial line distally ( g 7L) Subterminal segment widest at base tapering sharplyinwards at 04 of length forms narrow process supporting terminal segment

Variation mdash All individuals are characteristically dark orange to red witha silver-blue sheen to the carapace while the chelipeds vary in colour frombright orange-red to a lighter yellow-orange All individuals are characterized byhighly vaulted carapaces and downwardly projecting frontal lobes The postfrontalcrest which is most pronounced laterally (from directly above the orbits to theanterolateral margin) and incomplete medially is often more distinct in the smaller

POTAMONAUTES LIVIDUS NOV 157

individuals Chelipeds are not always typically arched enclosing a large ovoidspace as in the holotype Chelipeds of smaller individuals although in ated areless arched and often tight closing with the small cutting teeth more obviousChelipeds of females and small males in particular from the Mdibi and Universityof Zululand localities have propodi that are relatively high with in ated palmsand relatively short tightly closing chelae which project slightly downwardsHeterochely has been demonstrated in most Potamonautes-species occurring inSouth Africa (Siegfried 1972 Raubenheimer 1986 Stewart et al 1995 Stewart1997a b Stewart amp Cook 1998 Daniels et al 1998a Gouws et al 2000) Withinthe species 76 of the specimens were right-handed with 11 being left-handedand 13 being of equal or subequal (differing by less than one millimeter) sizeOf the males 79 were right-handed 8 left-handed and 13 equal or subequalFemales had 74 right-handedness 13 left-handedness and in 13 of caseschelipeds were equal or subequal The abdomen of mature females completelyoverlaps the coxae of the pereopods The smallest mature female had a CL of167 mm with the largest immature female having a CL of 159 indicating that thepubertal moult occurs approximately between the 14 mm and 18 mm size classes

Remarks mdash Potamonautes lividus sp nov can readily be distinguished from theten other species in the genus Potamonautes known to occur within South AfricaPotamonautes warreni Calman 1918 P dentatus P parvispina and P unispinusall bear a singular spine or a series of teeth on the anterolateral margins whereasP lividus sp nov is smooth Potamonautes perlatus P sidneyi and P granularisare all larger crabs with in ated arched carapaces with complete distinct post-frontal crests and scabrosity or granulation of the anterior margins orbits epi-branchial corners or postfrontal crests Potamonautes lividus sp nov has smoothcarapace margins and a incomplete postfrontal crest The terminal segment ofgonopod 1 in P lividus sp nov is relatively short and triangular and curves awayfrom the medial line when viewed posteriorly while that of P sidneyi is relativelylonger more slender and more S-shaped The postfrontal crest of P sidneyi mayjoin the anterolateral margin at a relatively sharp angle and form a pronouncedepibranchial corner along the anterolateral margin The anterolateral margin inP lividus sp nov is more rounded and the epibranchial corners slope down to-wards the anks Potamonautes granularis is chocolate brown with orange tips tothe chelipeds Potamonautes brincki is a smaller crab with a smoother carapacethough also chocolate to reddish-brown in colour with a nely granulated antero-lateral margin which does not curve in over the carapace in the branchial region(Stewart 1997b) Potamonautes depressus and P clarus both have rounded epi-branchial corners and smooth carapaces though these are relatively shallow andhave attened dorsal surfaces Both are characterized by long slender limbs Pota-monautes depressus is brown to green-brown in colour while P clarus is brightorange in colour

158 G GOUWS B A STEWART amp P E REAVELL

A number of species from further a eld bear a super cial resemblance toP lividus sp nov particularly with regard to carapace morphology though in mostcases they can be readily distinguished Potamonautes pilosus Hilgendorf 1898 isknown from East Africa and is a small crab with a CWW of less than 25 mmSpecimens possess a weak postfrontal crest which along with the anterolateralmargin can be granulated (Hilgendorf 1898 Bott 1955) Potamonautes neumanniHilgendorf 1898 is known from East Africa and has a characteristically vaultedcarapace without a complete distinct postfrontal crest (Hilgendorf 1898 Bott1955) The postfrontal crest is more distinct in P lividus particularly laterally andthe exorbital teeth are sharper and more de ned in P lividus than in P neumanniThe terminal segment of gonopod 1 is longer and more slender in P neumannithan in P lividus and curves distinctly outwards The subterminal segment ofgonopod 1 is wider at its apex in P neumanni than in P lividus Additionally thecarapace of preserved specimens of P neumanni is typically grey in colour whileliving specimens are violet in colour with bright olive-green limbs and chelipeds(Hilgendorf 1898) Potamonautes ballayi acristatus Bott 1955 has an incompletepostfrontal crest only present above the orbits and small and blunt exorbital teethThe major chela although highly arched and the minor chela are long and moreslender than those of P lividus sp nov The terminal segment of gonopod 1 ofP granviki Colosi 1924 is curved towards the medial line when viewed posteriorly(Bott 1955) The chelae of both P berardi berardi Audouin 1826 and P b ignestiiParisi 1923 are relatively short and high with stout downward-projecting ngersThe anterior margin of the frontal lobe of P b berardi shows a distinct invaginationand the anterolateral margin appears sharp and less rounded than in P lividus spnov while the postfrontal crest of P b ignestii is complete and has a fairly longmedial groove Potamonautes emini emini Hilgendorf 1892 are generally smallcrabs with a less in ated carapace and short stout chelipeds The subterminaland terminal segments of gonopod 1 are of more or less equal size (Bott 1955)Potamonautes e semilunaris Bott 1955 and P luashiensis Bott 1955 are alsosmall crabs (CWW lt 20 mm) with the postfrontal crest only visible laterally andin the case of P luashiensis the anterolateral margin and postfrontal crest mayshow granulation Potamonautes didieri Rathbun 1904 possesses a more completerounded postfrontal crest and shorter more stout chelipeds (Bott 1955)

ACKNOWLEDGEMENTS

Financial assistance was kindly provided by the World Wildlife Fund - SouthAfrica the Foundation for Research Development and the University of ZululandThe KwaZulu-Natal Nature Conservation Services provided accommodation and

POTAMONAUTES LIVIDUS NOV 159

logistic support Liz Hoenson Peter Cook Mike Coke and Tyrone Ridgway arethanked for assistance in the eld and Michelle van der Merwe is thanked foraiding in the photography and drafting of gures The authors wish to thank ananonymous reviewer for comments on the manuscript

REFERENCES

BARNARD K H 1935 Scienti c results of the Vernay-Lang Kalahari expedition March toSeptember 1930 Crustacea Ann Transvaal Mus 16 481-492

mdash mdash 1950 Descriptive catalogue of South African decapod Crustacea (crabs and shrimps) AnnSouth African Mus 38 1-837

BOCK W J 1986 Species concepts speciation and macroevolution In K IWATSUKIP H RAVEN amp W J BOCK (eds) Modern aspects of species 31-57 (University of TokyoPress Tokyo)

BOTT R 1955 Die Suumlsswasserkrabben von Afrika (Crust Decap) und ihre StammesgeschichteAnn Mus R Congo Belge (C Zool) 1 (33) 209-352 pls 1-30

BRUTON M N 1980 An outline of the ecology of the Mgobezeleni lake system at Sodwana withemphasis on the mangrove community In M N BRUTON amp K H COOPER (eds) Studieson the ecology of Maputaland 408-426 (Rhodes University Grahamstown)

CUMBERLIDGE N 1986 Ventilation of the branchial chambers in the amphibious West Africanfreshwater crab Sudanonautes (Convexonautes) aubryi monodi (Balss 1929) (BrachyuraPotamonautidae)Hydrobiol 134 53-65

mdash mdash 1991 The respiratory system of Globonautes macropus (Rathbun 1898) a terrestrialfreshwater crab from Liberia (GecarcinucoideaGecarcinucidae)Crustaceana 61 (1) 69-80

DANIELS S R B A STEWART amp M J GIBBONS 1998a Potamonautes granularis sp nov(Brachyura Potamonautidae) a new cryptic species of river crab from the Olifants Riversystem South Africa Crustaceana 71 (8) 885-903

mdash mdash mdash mdash amp mdash mdash 1998b Genetic and morphometric variation in the potamonautid river crabPotamonautes parvispina (Decapoda Potamonautidae) from two Western Cape rivers SouthAfrica Journ nat Hist London 32 1245-1258

mdash mdash mdash mdash amp mdash mdash 1999 Genetic structure among populations of Potamonautes perlatus(Decapoda Potamonautidae) from the Olifants River system in the Western Cape SouthAfrica Journ Zool London 249 (2) 137-142

DIacuteAZ H amp G RODRIacuteGUEZ 1977 The branchial chamber in terrestrial crabs a comparative studyBiol Bull Woods Hole 153 485-504

GOUWS G B A STEWART amp M COKE 2000 Evidence for a new species of river crab(Decapoda Brachyura Potamonautidae) from the Drakensberg South Africa Journ CrustBiol 20 (4) 743-758

GREENAWAY P amp H H TAYLOR 1976 Aerial gas exchange in Australian arid-zone crabParathelphusa transversa Von Martens Nature London 262 711-713

HILGENDORF F 1898 Die Land- und Suumlsswasser-Dekapoden Ostafrikas Die Thierwelt DeutschOst-Afrikas 4 (7) 1-37

LENZ H 1912 Afrikanische Crustaceen aus schwedischen Sammlungen Ark Zool 7 (29) 1-10MARKERT C L amp I FAULHABER 1965 Lactate dehydrogenase isozyme patterns of sh Journ

exp Zool 159 319-332MAYR E 1963 Animal species and evolution i-xiv 1-797 (Harvard University Press Cambridge

Massachusetts)mdash mdash 1970 Populations species and evolution i-xv 1-453 (Harvard University Press Cambridge

Massachusetts)

156 G GOUWS B A STEWART amp P E REAVELL

between sternites 3 and 4 complete laterally becoming shallower mediallysloping sharply towards abdominopelvic region

Third maxillipeds ( gs 6C 7E) Filling entire buccal frame except for ovalefferent respiratory openings short agellum present on exopods ischium smoothwith moderately deep vertical groove

Mandibular palp ( g 7F G H) Mandibular palp with two segments terminalsegment undivided with a dense tuft of setae on posterior surface of angeof terminal segment Margins generally hirsute Subterminal segment slightlyenlarged distally

Chelipeds and walking legs ( gs 6A 7C D) Chelipeds markedly unequaldactylus of right cheliped strongly arched 163 times length of dactylus of leftcheliped Both dactyli armed with up to 20 cutting teeth three to four of whichare slightly larger and more prominent Propodus of right cheliped markedlyin ated 168 times longer and 20 times wider than that of left cheliped Pollexpossesses 20 cutting teeth four to ve of which are more prominent Carpi ofboth chelipeds possess one prominent and three rudimentary teeth Margins ofmeri granulose small blunt spine on anterior surface no spine on anterior-inferiormargin Pereopods generally slender (pereopod 2 merus length width D 328 andpereopod 5 merus lengthwidth D 271) P3 longest P5 shortest ventral marginsof propodi and meri smooth dorsal margin with ne sharp bristles dactyli endingin sharp points with margins bearing a series of sharp spinelike bristles

Pleon ( gs 6B 7B) First ve segments broad and short last two segmentslonger terminal segment rounded at distal end

Pleopods ( g 7I J K) Pleopod 1 (gonopod 1) terminal segment short 025times length of subterminal segment terminal segment curves away from mid-line when viewed posteriorly widest at base ending in pointed tip Subterminalsegment of pleopod 1 tapers distally inner lateral margin slightly irregular outerlateral margin straighter both margins hirsute Posterior surface with twisting lon-gitudinal groove extending length of subterminal and terminal segment Groovenot visible on anterior surface Posterior surface and margins of groove hirsutePleopod 2 (gonopod 2) terminal segment lament-like 05 the length of subter-minal segment curving slightly towards medial line proximally curves away frommedial line distally ( g 7L) Subterminal segment widest at base tapering sharplyinwards at 04 of length forms narrow process supporting terminal segment

Variation mdash All individuals are characteristically dark orange to red witha silver-blue sheen to the carapace while the chelipeds vary in colour frombright orange-red to a lighter yellow-orange All individuals are characterized byhighly vaulted carapaces and downwardly projecting frontal lobes The postfrontalcrest which is most pronounced laterally (from directly above the orbits to theanterolateral margin) and incomplete medially is often more distinct in the smaller

POTAMONAUTES LIVIDUS NOV 157

individuals Chelipeds are not always typically arched enclosing a large ovoidspace as in the holotype Chelipeds of smaller individuals although in ated areless arched and often tight closing with the small cutting teeth more obviousChelipeds of females and small males in particular from the Mdibi and Universityof Zululand localities have propodi that are relatively high with in ated palmsand relatively short tightly closing chelae which project slightly downwardsHeterochely has been demonstrated in most Potamonautes-species occurring inSouth Africa (Siegfried 1972 Raubenheimer 1986 Stewart et al 1995 Stewart1997a b Stewart amp Cook 1998 Daniels et al 1998a Gouws et al 2000) Withinthe species 76 of the specimens were right-handed with 11 being left-handedand 13 being of equal or subequal (differing by less than one millimeter) sizeOf the males 79 were right-handed 8 left-handed and 13 equal or subequalFemales had 74 right-handedness 13 left-handedness and in 13 of caseschelipeds were equal or subequal The abdomen of mature females completelyoverlaps the coxae of the pereopods The smallest mature female had a CL of167 mm with the largest immature female having a CL of 159 indicating that thepubertal moult occurs approximately between the 14 mm and 18 mm size classes

Remarks mdash Potamonautes lividus sp nov can readily be distinguished from theten other species in the genus Potamonautes known to occur within South AfricaPotamonautes warreni Calman 1918 P dentatus P parvispina and P unispinusall bear a singular spine or a series of teeth on the anterolateral margins whereasP lividus sp nov is smooth Potamonautes perlatus P sidneyi and P granularisare all larger crabs with in ated arched carapaces with complete distinct post-frontal crests and scabrosity or granulation of the anterior margins orbits epi-branchial corners or postfrontal crests Potamonautes lividus sp nov has smoothcarapace margins and a incomplete postfrontal crest The terminal segment ofgonopod 1 in P lividus sp nov is relatively short and triangular and curves awayfrom the medial line when viewed posteriorly while that of P sidneyi is relativelylonger more slender and more S-shaped The postfrontal crest of P sidneyi mayjoin the anterolateral margin at a relatively sharp angle and form a pronouncedepibranchial corner along the anterolateral margin The anterolateral margin inP lividus sp nov is more rounded and the epibranchial corners slope down to-wards the anks Potamonautes granularis is chocolate brown with orange tips tothe chelipeds Potamonautes brincki is a smaller crab with a smoother carapacethough also chocolate to reddish-brown in colour with a nely granulated antero-lateral margin which does not curve in over the carapace in the branchial region(Stewart 1997b) Potamonautes depressus and P clarus both have rounded epi-branchial corners and smooth carapaces though these are relatively shallow andhave attened dorsal surfaces Both are characterized by long slender limbs Pota-monautes depressus is brown to green-brown in colour while P clarus is brightorange in colour

158 G GOUWS B A STEWART amp P E REAVELL

A number of species from further a eld bear a super cial resemblance toP lividus sp nov particularly with regard to carapace morphology though in mostcases they can be readily distinguished Potamonautes pilosus Hilgendorf 1898 isknown from East Africa and is a small crab with a CWW of less than 25 mmSpecimens possess a weak postfrontal crest which along with the anterolateralmargin can be granulated (Hilgendorf 1898 Bott 1955) Potamonautes neumanniHilgendorf 1898 is known from East Africa and has a characteristically vaultedcarapace without a complete distinct postfrontal crest (Hilgendorf 1898 Bott1955) The postfrontal crest is more distinct in P lividus particularly laterally andthe exorbital teeth are sharper and more de ned in P lividus than in P neumanniThe terminal segment of gonopod 1 is longer and more slender in P neumannithan in P lividus and curves distinctly outwards The subterminal segment ofgonopod 1 is wider at its apex in P neumanni than in P lividus Additionally thecarapace of preserved specimens of P neumanni is typically grey in colour whileliving specimens are violet in colour with bright olive-green limbs and chelipeds(Hilgendorf 1898) Potamonautes ballayi acristatus Bott 1955 has an incompletepostfrontal crest only present above the orbits and small and blunt exorbital teethThe major chela although highly arched and the minor chela are long and moreslender than those of P lividus sp nov The terminal segment of gonopod 1 ofP granviki Colosi 1924 is curved towards the medial line when viewed posteriorly(Bott 1955) The chelae of both P berardi berardi Audouin 1826 and P b ignestiiParisi 1923 are relatively short and high with stout downward-projecting ngersThe anterior margin of the frontal lobe of P b berardi shows a distinct invaginationand the anterolateral margin appears sharp and less rounded than in P lividus spnov while the postfrontal crest of P b ignestii is complete and has a fairly longmedial groove Potamonautes emini emini Hilgendorf 1892 are generally smallcrabs with a less in ated carapace and short stout chelipeds The subterminaland terminal segments of gonopod 1 are of more or less equal size (Bott 1955)Potamonautes e semilunaris Bott 1955 and P luashiensis Bott 1955 are alsosmall crabs (CWW lt 20 mm) with the postfrontal crest only visible laterally andin the case of P luashiensis the anterolateral margin and postfrontal crest mayshow granulation Potamonautes didieri Rathbun 1904 possesses a more completerounded postfrontal crest and shorter more stout chelipeds (Bott 1955)

ACKNOWLEDGEMENTS

Financial assistance was kindly provided by the World Wildlife Fund - SouthAfrica the Foundation for Research Development and the University of ZululandThe KwaZulu-Natal Nature Conservation Services provided accommodation and

POTAMONAUTES LIVIDUS NOV 159

logistic support Liz Hoenson Peter Cook Mike Coke and Tyrone Ridgway arethanked for assistance in the eld and Michelle van der Merwe is thanked foraiding in the photography and drafting of gures The authors wish to thank ananonymous reviewer for comments on the manuscript

REFERENCES

BARNARD K H 1935 Scienti c results of the Vernay-Lang Kalahari expedition March toSeptember 1930 Crustacea Ann Transvaal Mus 16 481-492

mdash mdash 1950 Descriptive catalogue of South African decapod Crustacea (crabs and shrimps) AnnSouth African Mus 38 1-837

BOCK W J 1986 Species concepts speciation and macroevolution In K IWATSUKIP H RAVEN amp W J BOCK (eds) Modern aspects of species 31-57 (University of TokyoPress Tokyo)

BOTT R 1955 Die Suumlsswasserkrabben von Afrika (Crust Decap) und ihre StammesgeschichteAnn Mus R Congo Belge (C Zool) 1 (33) 209-352 pls 1-30

BRUTON M N 1980 An outline of the ecology of the Mgobezeleni lake system at Sodwana withemphasis on the mangrove community In M N BRUTON amp K H COOPER (eds) Studieson the ecology of Maputaland 408-426 (Rhodes University Grahamstown)

CUMBERLIDGE N 1986 Ventilation of the branchial chambers in the amphibious West Africanfreshwater crab Sudanonautes (Convexonautes) aubryi monodi (Balss 1929) (BrachyuraPotamonautidae)Hydrobiol 134 53-65

mdash mdash 1991 The respiratory system of Globonautes macropus (Rathbun 1898) a terrestrialfreshwater crab from Liberia (GecarcinucoideaGecarcinucidae)Crustaceana 61 (1) 69-80

DANIELS S R B A STEWART amp M J GIBBONS 1998a Potamonautes granularis sp nov(Brachyura Potamonautidae) a new cryptic species of river crab from the Olifants Riversystem South Africa Crustaceana 71 (8) 885-903

mdash mdash mdash mdash amp mdash mdash 1998b Genetic and morphometric variation in the potamonautid river crabPotamonautes parvispina (Decapoda Potamonautidae) from two Western Cape rivers SouthAfrica Journ nat Hist London 32 1245-1258

mdash mdash mdash mdash amp mdash mdash 1999 Genetic structure among populations of Potamonautes perlatus(Decapoda Potamonautidae) from the Olifants River system in the Western Cape SouthAfrica Journ Zool London 249 (2) 137-142

DIacuteAZ H amp G RODRIacuteGUEZ 1977 The branchial chamber in terrestrial crabs a comparative studyBiol Bull Woods Hole 153 485-504

GOUWS G B A STEWART amp M COKE 2000 Evidence for a new species of river crab(Decapoda Brachyura Potamonautidae) from the Drakensberg South Africa Journ CrustBiol 20 (4) 743-758

GREENAWAY P amp H H TAYLOR 1976 Aerial gas exchange in Australian arid-zone crabParathelphusa transversa Von Martens Nature London 262 711-713

HILGENDORF F 1898 Die Land- und Suumlsswasser-Dekapoden Ostafrikas Die Thierwelt DeutschOst-Afrikas 4 (7) 1-37

LENZ H 1912 Afrikanische Crustaceen aus schwedischen Sammlungen Ark Zool 7 (29) 1-10MARKERT C L amp I FAULHABER 1965 Lactate dehydrogenase isozyme patterns of sh Journ

exp Zool 159 319-332MAYR E 1963 Animal species and evolution i-xiv 1-797 (Harvard University Press Cambridge

Massachusetts)mdash mdash 1970 Populations species and evolution i-xv 1-453 (Harvard University Press Cambridge

Massachusetts)

POTAMONAUTES LIVIDUS NOV 157

individuals Chelipeds are not always typically arched enclosing a large ovoidspace as in the holotype Chelipeds of smaller individuals although in ated areless arched and often tight closing with the small cutting teeth more obviousChelipeds of females and small males in particular from the Mdibi and Universityof Zululand localities have propodi that are relatively high with in ated palmsand relatively short tightly closing chelae which project slightly downwardsHeterochely has been demonstrated in most Potamonautes-species occurring inSouth Africa (Siegfried 1972 Raubenheimer 1986 Stewart et al 1995 Stewart1997a b Stewart amp Cook 1998 Daniels et al 1998a Gouws et al 2000) Withinthe species 76 of the specimens were right-handed with 11 being left-handedand 13 being of equal or subequal (differing by less than one millimeter) sizeOf the males 79 were right-handed 8 left-handed and 13 equal or subequalFemales had 74 right-handedness 13 left-handedness and in 13 of caseschelipeds were equal or subequal The abdomen of mature females completelyoverlaps the coxae of the pereopods The smallest mature female had a CL of167 mm with the largest immature female having a CL of 159 indicating that thepubertal moult occurs approximately between the 14 mm and 18 mm size classes

Remarks mdash Potamonautes lividus sp nov can readily be distinguished from theten other species in the genus Potamonautes known to occur within South AfricaPotamonautes warreni Calman 1918 P dentatus P parvispina and P unispinusall bear a singular spine or a series of teeth on the anterolateral margins whereasP lividus sp nov is smooth Potamonautes perlatus P sidneyi and P granularisare all larger crabs with in ated arched carapaces with complete distinct post-frontal crests and scabrosity or granulation of the anterior margins orbits epi-branchial corners or postfrontal crests Potamonautes lividus sp nov has smoothcarapace margins and a incomplete postfrontal crest The terminal segment ofgonopod 1 in P lividus sp nov is relatively short and triangular and curves awayfrom the medial line when viewed posteriorly while that of P sidneyi is relativelylonger more slender and more S-shaped The postfrontal crest of P sidneyi mayjoin the anterolateral margin at a relatively sharp angle and form a pronouncedepibranchial corner along the anterolateral margin The anterolateral margin inP lividus sp nov is more rounded and the epibranchial corners slope down to-wards the anks Potamonautes granularis is chocolate brown with orange tips tothe chelipeds Potamonautes brincki is a smaller crab with a smoother carapacethough also chocolate to reddish-brown in colour with a nely granulated antero-lateral margin which does not curve in over the carapace in the branchial region(Stewart 1997b) Potamonautes depressus and P clarus both have rounded epi-branchial corners and smooth carapaces though these are relatively shallow andhave attened dorsal surfaces Both are characterized by long slender limbs Pota-monautes depressus is brown to green-brown in colour while P clarus is brightorange in colour

158 G GOUWS B A STEWART amp P E REAVELL

A number of species from further a eld bear a super cial resemblance toP lividus sp nov particularly with regard to carapace morphology though in mostcases they can be readily distinguished Potamonautes pilosus Hilgendorf 1898 isknown from East Africa and is a small crab with a CWW of less than 25 mmSpecimens possess a weak postfrontal crest which along with the anterolateralmargin can be granulated (Hilgendorf 1898 Bott 1955) Potamonautes neumanniHilgendorf 1898 is known from East Africa and has a characteristically vaultedcarapace without a complete distinct postfrontal crest (Hilgendorf 1898 Bott1955) The postfrontal crest is more distinct in P lividus particularly laterally andthe exorbital teeth are sharper and more de ned in P lividus than in P neumanniThe terminal segment of gonopod 1 is longer and more slender in P neumannithan in P lividus and curves distinctly outwards The subterminal segment ofgonopod 1 is wider at its apex in P neumanni than in P lividus Additionally thecarapace of preserved specimens of P neumanni is typically grey in colour whileliving specimens are violet in colour with bright olive-green limbs and chelipeds(Hilgendorf 1898) Potamonautes ballayi acristatus Bott 1955 has an incompletepostfrontal crest only present above the orbits and small and blunt exorbital teethThe major chela although highly arched and the minor chela are long and moreslender than those of P lividus sp nov The terminal segment of gonopod 1 ofP granviki Colosi 1924 is curved towards the medial line when viewed posteriorly(Bott 1955) The chelae of both P berardi berardi Audouin 1826 and P b ignestiiParisi 1923 are relatively short and high with stout downward-projecting ngersThe anterior margin of the frontal lobe of P b berardi shows a distinct invaginationand the anterolateral margin appears sharp and less rounded than in P lividus spnov while the postfrontal crest of P b ignestii is complete and has a fairly longmedial groove Potamonautes emini emini Hilgendorf 1892 are generally smallcrabs with a less in ated carapace and short stout chelipeds The subterminaland terminal segments of gonopod 1 are of more or less equal size (Bott 1955)Potamonautes e semilunaris Bott 1955 and P luashiensis Bott 1955 are alsosmall crabs (CWW lt 20 mm) with the postfrontal crest only visible laterally andin the case of P luashiensis the anterolateral margin and postfrontal crest mayshow granulation Potamonautes didieri Rathbun 1904 possesses a more completerounded postfrontal crest and shorter more stout chelipeds (Bott 1955)

ACKNOWLEDGEMENTS

Financial assistance was kindly provided by the World Wildlife Fund - SouthAfrica the Foundation for Research Development and the University of ZululandThe KwaZulu-Natal Nature Conservation Services provided accommodation and

POTAMONAUTES LIVIDUS NOV 159

logistic support Liz Hoenson Peter Cook Mike Coke and Tyrone Ridgway arethanked for assistance in the eld and Michelle van der Merwe is thanked foraiding in the photography and drafting of gures The authors wish to thank ananonymous reviewer for comments on the manuscript

REFERENCES

BARNARD K H 1935 Scienti c results of the Vernay-Lang Kalahari expedition March toSeptember 1930 Crustacea Ann Transvaal Mus 16 481-492

mdash mdash 1950 Descriptive catalogue of South African decapod Crustacea (crabs and shrimps) AnnSouth African Mus 38 1-837

BOCK W J 1986 Species concepts speciation and macroevolution In K IWATSUKIP H RAVEN amp W J BOCK (eds) Modern aspects of species 31-57 (University of TokyoPress Tokyo)

BOTT R 1955 Die Suumlsswasserkrabben von Afrika (Crust Decap) und ihre StammesgeschichteAnn Mus R Congo Belge (C Zool) 1 (33) 209-352 pls 1-30

BRUTON M N 1980 An outline of the ecology of the Mgobezeleni lake system at Sodwana withemphasis on the mangrove community In M N BRUTON amp K H COOPER (eds) Studieson the ecology of Maputaland 408-426 (Rhodes University Grahamstown)

CUMBERLIDGE N 1986 Ventilation of the branchial chambers in the amphibious West Africanfreshwater crab Sudanonautes (Convexonautes) aubryi monodi (Balss 1929) (BrachyuraPotamonautidae)Hydrobiol 134 53-65

mdash mdash 1991 The respiratory system of Globonautes macropus (Rathbun 1898) a terrestrialfreshwater crab from Liberia (GecarcinucoideaGecarcinucidae)Crustaceana 61 (1) 69-80

DANIELS S R B A STEWART amp M J GIBBONS 1998a Potamonautes granularis sp nov(Brachyura Potamonautidae) a new cryptic species of river crab from the Olifants Riversystem South Africa Crustaceana 71 (8) 885-903

mdash mdash mdash mdash amp mdash mdash 1998b Genetic and morphometric variation in the potamonautid river crabPotamonautes parvispina (Decapoda Potamonautidae) from two Western Cape rivers SouthAfrica Journ nat Hist London 32 1245-1258

mdash mdash mdash mdash amp mdash mdash 1999 Genetic structure among populations of Potamonautes perlatus(Decapoda Potamonautidae) from the Olifants River system in the Western Cape SouthAfrica Journ Zool London 249 (2) 137-142

DIacuteAZ H amp G RODRIacuteGUEZ 1977 The branchial chamber in terrestrial crabs a comparative studyBiol Bull Woods Hole 153 485-504

GOUWS G B A STEWART amp M COKE 2000 Evidence for a new species of river crab(Decapoda Brachyura Potamonautidae) from the Drakensberg South Africa Journ CrustBiol 20 (4) 743-758

GREENAWAY P amp H H TAYLOR 1976 Aerial gas exchange in Australian arid-zone crabParathelphusa transversa Von Martens Nature London 262 711-713

HILGENDORF F 1898 Die Land- und Suumlsswasser-Dekapoden Ostafrikas Die Thierwelt DeutschOst-Afrikas 4 (7) 1-37

LENZ H 1912 Afrikanische Crustaceen aus schwedischen Sammlungen Ark Zool 7 (29) 1-10MARKERT C L amp I FAULHABER 1965 Lactate dehydrogenase isozyme patterns of sh Journ

exp Zool 159 319-332MAYR E 1963 Animal species and evolution i-xiv 1-797 (Harvard University Press Cambridge

Massachusetts)mdash mdash 1970 Populations species and evolution i-xv 1-453 (Harvard University Press Cambridge

Massachusetts)

158 G GOUWS B A STEWART amp P E REAVELL

A number of species from further a eld bear a super cial resemblance toP lividus sp nov particularly with regard to carapace morphology though in mostcases they can be readily distinguished Potamonautes pilosus Hilgendorf 1898 isknown from East Africa and is a small crab with a CWW of less than 25 mmSpecimens possess a weak postfrontal crest which along with the anterolateralmargin can be granulated (Hilgendorf 1898 Bott 1955) Potamonautes neumanniHilgendorf 1898 is known from East Africa and has a characteristically vaultedcarapace without a complete distinct postfrontal crest (Hilgendorf 1898 Bott1955) The postfrontal crest is more distinct in P lividus particularly laterally andthe exorbital teeth are sharper and more de ned in P lividus than in P neumanniThe terminal segment of gonopod 1 is longer and more slender in P neumannithan in P lividus and curves distinctly outwards The subterminal segment ofgonopod 1 is wider at its apex in P neumanni than in P lividus Additionally thecarapace of preserved specimens of P neumanni is typically grey in colour whileliving specimens are violet in colour with bright olive-green limbs and chelipeds(Hilgendorf 1898) Potamonautes ballayi acristatus Bott 1955 has an incompletepostfrontal crest only present above the orbits and small and blunt exorbital teethThe major chela although highly arched and the minor chela are long and moreslender than those of P lividus sp nov The terminal segment of gonopod 1 ofP granviki Colosi 1924 is curved towards the medial line when viewed posteriorly(Bott 1955) The chelae of both P berardi berardi Audouin 1826 and P b ignestiiParisi 1923 are relatively short and high with stout downward-projecting ngersThe anterior margin of the frontal lobe of P b berardi shows a distinct invaginationand the anterolateral margin appears sharp and less rounded than in P lividus spnov while the postfrontal crest of P b ignestii is complete and has a fairly longmedial groove Potamonautes emini emini Hilgendorf 1892 are generally smallcrabs with a less in ated carapace and short stout chelipeds The subterminaland terminal segments of gonopod 1 are of more or less equal size (Bott 1955)Potamonautes e semilunaris Bott 1955 and P luashiensis Bott 1955 are alsosmall crabs (CWW lt 20 mm) with the postfrontal crest only visible laterally andin the case of P luashiensis the anterolateral margin and postfrontal crest mayshow granulation Potamonautes didieri Rathbun 1904 possesses a more completerounded postfrontal crest and shorter more stout chelipeds (Bott 1955)

ACKNOWLEDGEMENTS

Financial assistance was kindly provided by the World Wildlife Fund - SouthAfrica the Foundation for Research Development and the University of ZululandThe KwaZulu-Natal Nature Conservation Services provided accommodation and

POTAMONAUTES LIVIDUS NOV 159

logistic support Liz Hoenson Peter Cook Mike Coke and Tyrone Ridgway arethanked for assistance in the eld and Michelle van der Merwe is thanked foraiding in the photography and drafting of gures The authors wish to thank ananonymous reviewer for comments on the manuscript

REFERENCES

BARNARD K H 1935 Scienti c results of the Vernay-Lang Kalahari expedition March toSeptember 1930 Crustacea Ann Transvaal Mus 16 481-492

mdash mdash 1950 Descriptive catalogue of South African decapod Crustacea (crabs and shrimps) AnnSouth African Mus 38 1-837

BOCK W J 1986 Species concepts speciation and macroevolution In K IWATSUKIP H RAVEN amp W J BOCK (eds) Modern aspects of species 31-57 (University of TokyoPress Tokyo)

BOTT R 1955 Die Suumlsswasserkrabben von Afrika (Crust Decap) und ihre StammesgeschichteAnn Mus R Congo Belge (C Zool) 1 (33) 209-352 pls 1-30

BRUTON M N 1980 An outline of the ecology of the Mgobezeleni lake system at Sodwana withemphasis on the mangrove community In M N BRUTON amp K H COOPER (eds) Studieson the ecology of Maputaland 408-426 (Rhodes University Grahamstown)

CUMBERLIDGE N 1986 Ventilation of the branchial chambers in the amphibious West Africanfreshwater crab Sudanonautes (Convexonautes) aubryi monodi (Balss 1929) (BrachyuraPotamonautidae)Hydrobiol 134 53-65

mdash mdash 1991 The respiratory system of Globonautes macropus (Rathbun 1898) a terrestrialfreshwater crab from Liberia (GecarcinucoideaGecarcinucidae)Crustaceana 61 (1) 69-80

DANIELS S R B A STEWART amp M J GIBBONS 1998a Potamonautes granularis sp nov(Brachyura Potamonautidae) a new cryptic species of river crab from the Olifants Riversystem South Africa Crustaceana 71 (8) 885-903

mdash mdash mdash mdash amp mdash mdash 1998b Genetic and morphometric variation in the potamonautid river crabPotamonautes parvispina (Decapoda Potamonautidae) from two Western Cape rivers SouthAfrica Journ nat Hist London 32 1245-1258

mdash mdash mdash mdash amp mdash mdash 1999 Genetic structure among populations of Potamonautes perlatus(Decapoda Potamonautidae) from the Olifants River system in the Western Cape SouthAfrica Journ Zool London 249 (2) 137-142

DIacuteAZ H amp G RODRIacuteGUEZ 1977 The branchial chamber in terrestrial crabs a comparative studyBiol Bull Woods Hole 153 485-504

GOUWS G B A STEWART amp M COKE 2000 Evidence for a new species of river crab(Decapoda Brachyura Potamonautidae) from the Drakensberg South Africa Journ CrustBiol 20 (4) 743-758

GREENAWAY P amp H H TAYLOR 1976 Aerial gas exchange in Australian arid-zone crabParathelphusa transversa Von Martens Nature London 262 711-713

HILGENDORF F 1898 Die Land- und Suumlsswasser-Dekapoden Ostafrikas Die Thierwelt DeutschOst-Afrikas 4 (7) 1-37

LENZ H 1912 Afrikanische Crustaceen aus schwedischen Sammlungen Ark Zool 7 (29) 1-10MARKERT C L amp I FAULHABER 1965 Lactate dehydrogenase isozyme patterns of sh Journ

exp Zool 159 319-332MAYR E 1963 Animal species and evolution i-xiv 1-797 (Harvard University Press Cambridge

Massachusetts)mdash mdash 1970 Populations species and evolution i-xv 1-453 (Harvard University Press Cambridge

Massachusetts)

POTAMONAUTES LIVIDUS NOV 159

logistic support Liz Hoenson Peter Cook Mike Coke and Tyrone Ridgway arethanked for assistance in the eld and Michelle van der Merwe is thanked foraiding in the photography and drafting of gures The authors wish to thank ananonymous reviewer for comments on the manuscript

REFERENCES

BARNARD K H 1935 Scienti c results of the Vernay-Lang Kalahari expedition March toSeptember 1930 Crustacea Ann Transvaal Mus 16 481-492

mdash mdash 1950 Descriptive catalogue of South African decapod Crustacea (crabs and shrimps) AnnSouth African Mus 38 1-837

BOCK W J 1986 Species concepts speciation and macroevolution In K IWATSUKIP H RAVEN amp W J BOCK (eds) Modern aspects of species 31-57 (University of TokyoPress Tokyo)

BOTT R 1955 Die Suumlsswasserkrabben von Afrika (Crust Decap) und ihre StammesgeschichteAnn Mus R Congo Belge (C Zool) 1 (33) 209-352 pls 1-30

BRUTON M N 1980 An outline of the ecology of the Mgobezeleni lake system at Sodwana withemphasis on the mangrove community In M N BRUTON amp K H COOPER (eds) Studieson the ecology of Maputaland 408-426 (Rhodes University Grahamstown)

CUMBERLIDGE N 1986 Ventilation of the branchial chambers in the amphibious West Africanfreshwater crab Sudanonautes (Convexonautes) aubryi monodi (Balss 1929) (BrachyuraPotamonautidae)Hydrobiol 134 53-65

mdash mdash 1991 The respiratory system of Globonautes macropus (Rathbun 1898) a terrestrialfreshwater crab from Liberia (GecarcinucoideaGecarcinucidae)Crustaceana 61 (1) 69-80

DANIELS S R B A STEWART amp M J GIBBONS 1998a Potamonautes granularis sp nov(Brachyura Potamonautidae) a new cryptic species of river crab from the Olifants Riversystem South Africa Crustaceana 71 (8) 885-903

mdash mdash mdash mdash amp mdash mdash 1998b Genetic and morphometric variation in the potamonautid river crabPotamonautes parvispina (Decapoda Potamonautidae) from two Western Cape rivers SouthAfrica Journ nat Hist London 32 1245-1258

mdash mdash mdash mdash amp mdash mdash 1999 Genetic structure among populations of Potamonautes perlatus(Decapoda Potamonautidae) from the Olifants River system in the Western Cape SouthAfrica Journ Zool London 249 (2) 137-142

DIacuteAZ H amp G RODRIacuteGUEZ 1977 The branchial chamber in terrestrial crabs a comparative studyBiol Bull Woods Hole 153 485-504

GOUWS G B A STEWART amp M COKE 2000 Evidence for a new species of river crab(Decapoda Brachyura Potamonautidae) from the Drakensberg South Africa Journ CrustBiol 20 (4) 743-758

GREENAWAY P amp H H TAYLOR 1976 Aerial gas exchange in Australian arid-zone crabParathelphusa transversa Von Martens Nature London 262 711-713

HILGENDORF F 1898 Die Land- und Suumlsswasser-Dekapoden Ostafrikas Die Thierwelt DeutschOst-Afrikas 4 (7) 1-37

LENZ H 1912 Afrikanische Crustaceen aus schwedischen Sammlungen Ark Zool 7 (29) 1-10MARKERT C L amp I FAULHABER 1965 Lactate dehydrogenase isozyme patterns of sh Journ

exp Zool 159 319-332MAYR E 1963 Animal species and evolution i-xiv 1-797 (Harvard University Press Cambridge

Massachusetts)mdash mdash 1970 Populations species and evolution i-xv 1-453 (Harvard University Press Cambridge

Massachusetts)

160 G GOUWS B A STEWART amp P E REAVELL

MOLL E J 1980 Terrestrial plant ecology In M N BRUTON amp K H COOPER (eds) Studieson the ecology of Maputaland 52-68 (Rhodes University Grahamstown)

NEI M 1978 Estimation of average heterozygosity and genetic distance from a small number ofindividuals Genetics 89 583-590

RAUBENHEIMER C D 1986 Aspects of the biology of the freshwater crab Potamonautessidneyi with particular reference to general seasonality and female aggression i-xii 1-106(MSc Thesis Department of Biological Sciences University of Natal Durban)

RIDGEWAY G J S W SHERBURNE amp R D LEWIS 1970 Polymorphism in the esterase ofAtlantic herring Trans American Fish Soc 99 147-151

SHAW C R amp R B PRASAD 1970 Starch gel electrophoresis of enzymes mdash a compilation ofrecipes Biochem Genet 4 297-320

SIEGFRIED W R 1972 Handedness in the Cape River crab Potamonautes perlatus (M Edw)South African Journ Science 68 103-104

SNEATH P H A amp R R SOKAL 1973 Numerical taxonomy 1-573 (Freeman London)STATSOFT Inc 1996 STATISTICA for Windows (Tulsa Oklahoma USA)STEBBING T R R 1910 General catalogue of South African Crustacea Ann South African

Mus 6 281-593STEWART B A 1997a Biochemical and morphological evidence for a new species of river crab

Potamonautes parvispina sp nov (Brachyura Potamonautidae)Crustaceana 70 (6) 737-753mdash mdash 1997b Morphological and genetic differentiation between populations of river crabs

(Decapoda Potamonautidae) from the Western Cape South Africa with a taxonomic re-examination of Gecarcinautes brincki Zool Journ Linnean Soc London 119 1-21

STEWART B A M COKE amp P A COOK 1995 Potamonautes dentatus new species a fresh-water crab (Brachyura Potamoidea Potamonautidae) from KwaZulu-Natal South AfricaJourn Crust Biol 15 (3) 558-568

STEWART B A amp P A COOK 1998 Identi cation of a new species of river crab (DecapodaBrachyura Potamonautidae) from South Africa using morphological and genetic data JournCrust Biol 18 (3) 556-571

SWOFFORD D L amp R B SELANDER 1981 BIOSYS-1 A computer program for the analysisof allelic variation in population genetics and biochemical systematics Release 17 (David LSwofford Illinois Natural History Survey)

TAKEDA S M MATSUMASA S KIKUCHI S POOVACHIRANON amp M MURAI 1996 Variationin the branchial formula of semiterrestrial crabs (Decapoda Brachyura Grapsidae and Ocypo-didae) in relation to physiological adaptations to the environment Journ Crust Biol 16 (3)472-486

TAYLOR H H amp P GREENAWAY 1979 The structure of the gills and lungs of the arid zonecrab Holthuisana (Austrothelphusa) transversa (Brachyura Sundathelphusidae) includingobservations on arterial vessels within the gills Journ Zool London 189 359-384

THORPE J P 1982 The molecular clock hypothesisbiochemical evolution genetic differentiationand systematics Ann Rev Ecol Syst 13 139-168

THORPE J P amp A M SOLEacute-CAVA 1994 The use of allozyme electrophoresis in invertebratesystematics Zool Scr 23 3-18

WESSELS N G 1997 Aspects of the ecology and conservationof swamp forests in South Africa1-155 (MSc (Technology) Thesis Port Elizabeth Technikon Port Elizabeth South Africa)

WHITT G S 1970 Developmental genetics of the lactate dehydrogenase isozymes of sh Journexp Zool 175 1-35

First received 1 April 2000Final version accepted 31 July 2000