lackwell Publishing, LtdSystematics and phylogeny of ... · Pedibothrium maccallumi Caira & Pritchard, 1986 USNPC 36011 (holotype). Pedibothrium brevispine Linton, 1909 USNPC 9001

© The Norwegian Academy of Science and Letters • Zoologica Scripta, 32, 4, July 2003, pp367–396 367

Marques, F. P. L., Brooks, D. R. & Araújo, M. L. G. (2003). Systematics and phylogenyof Potamotrygonocestus (Platyhelminthes, Tetraphyllidea, Onchobothriidae) with descriptionsof three new species from freshwater potamotrygonids (Myliobatoidei, Potamotrygonidae).— Zoologica Scripta, 32, 367–396.Specimens of Potamotrygonocestus used in the present taxonomic and phylogenetic study werecollected in freshwater potamotrygonids from the Rio Paraná (Puerto Reconquista, Santa Fé,Argentina; 59°42′W, 29°29′S) during February 1995, and from the Amazon region of Brazilduring September to December 1996, supplemented by specimens previously deposited inmuseum collections. Six species of Potamotrygonocestus were recognized (P. amazonensis, P. chaoisp. n., P. fitzgeraldae sp. n., P. magdalenensis, P. maurae sp. n., P. travassosi ), for which an identificationkey is provided. Potamotrygonocestus orinocoensis is considered a junior synonym of P. travassosi.Additional specimens of Potamotrygonocestus may represent two undescribed species. A phylogeneticanalysis of six morphological characters for the six named species of Potamotrygonocestusgenerated a single tree eight steps long, with a consistency index of 0.87, a retention index of0.90, and a rescaled consistency index of 0.79 with the following topology: (P. maurae sp. n.((P. amazonensis + P. magdalenensis) (P. chaoi sp. n. (P. fitzgeraldae sp. n. + P. travassosi )))).Fernando P. L. Marques, Department of Zoology, University of Toronto, Toronto, Ontario M5S 3G5,Canada., Present address: Departamento de Zoologia, Instituto de Biociências, Universidade de SãoPaulo, Caixa Postal 11461 — São Paulo/SP 05422-970, Brazil. E-mail: [email protected], DanielR. Brooks, Department of Zoology, University of Toronto, Toronto, Ontario M5S 3G5, Canada, MariaL. G. Araújo, Laboratório de Histologia, Universidade do Amazonas, Av. Gen. Rodrigo Otávio Jordão,3000, Manaus AM 69000–000, Brazil

lackwell Publishing, LtdSystematics and phylogeny of Potamotrygonocestus (Platyhelminthes, Tetraphyllidea, Onchobothriidae) with descriptions of three new species from freshwater potamotrygonids (Myliobatoidei, Potamotrygonidae)FERNANDO P. L. MARQUES, DANIEL R. BROOKS & MARIA L. G. ARAÚJO

Accepted: 19 June 2002

IntroductionThe genus Potamotrygonocestus was first established for P.magdalenensis Brooks & Thorson, 1976, found in the endemicfreshwater potamotrygonid Potamotrygon magdalenae(Valenciennes, 1865) from Rio Magdalena in Colombia. Rego(1979) described Potamotrygonocestus travassosi in Potamotrygonorbignyi (Castelnau, 1855) from Rio Amazonas, Maicurú, Pará,Brazil. Subsequently, Potamotrygonocestus amazonensis Mayes,Brooks Thorson, 1981 was described in Potamotrygonconstellata (Vaillant, 1880) from the Upper Solimões Basin, Atalaiado Norte, Amazonas, Brazil. Brooks et al. (1981) provided thefirst systematic review of cestodes inhabiting freshwaterpotamotrygonids in which they described Potamotrygonocestusorinocoensis inhabiting Potamotrygon orbignyi from the deltaof Rio Orinoco in Venezuela. In their review, Brooks et al.(1981) considered Potamotrygonocestus travassosi to be speciesinquirenda, as Rego (1979) clearly mistook a proglottis of the

trypanorhynch eucestode Paroncomegas araya (Woodland,1934) Campbell et al., 1999 for one of Potamotrygonocestustravassosi in the original description. Hence, they recog-nized three diagnosable species within the genus for whichthey also proposed a phylogenetic hypothesis. In theirphylogenetic analysis, Brooks et al. (1981) suggested a closeaffinity among Potamotrygonocestus, Pachybothrium Baer &Euzet, 1962 and Pedibothrium Linton, 1909, and used thelatter two taxa as outgroups. In this study, we provide ataxonomic review of the genus Potamotrygonocestus based onspecimens collected by one of the authors and material frommuseum collections. Following this, we provide additionaljustification for the use of Pachybothrium and Pedibothriumas outgroups, and develop a new phylogenetic hypothesisfor the recognized species of Potamotrygonocestus. Finally, webriefly discuss the historical association between Potamotry-gonocestus, Pachybothrium and Pedibothrium and their hosts.

Systematics and phylogeny of Potamotrygonocestus • F. P. L. Marques et al.

368 Zoologica Scripta, 32, 4, July 2003, pp367–396 • © The Norwegian Academy of Science and Letters

Materials and methodsSpecimens of freshwater potamotrygonids were collected,using long-lines, from Rio Paraná (Puerto Reconquista, SantaFé, Argentina; 59°42′ W, 29°29′ S) during February 1995,and from the Amazon region of Brazil during September toDecember 1996. Live specimens and the majority of looseproglottides were removed from the spiral valve in situ, placedin freshwater, fixed with hot alcohol/formalin/acetic acid(AFA), and transferred to cool fixative. After 24 h, the wormswere transferred to 70% ethanol for storage. Given the smallsize of the specimens of Potamotrygonocestus, most of thecestodes were collected in the laboratory from the spiral valvesthat had been fixed in the field in warm 10% formalin. A listof hosts examined in the present study is provided in Table 1.

Whole mounts of all eucestodes were stained with aceto-carmine or Mayer’s haematoxylin, dehydrated in ethanol, clearedin methyl salicylate, and mounted in Canada balsam. Serialtransverse sections of specimens in paraffin were cut at 8 µmintervals and stained with haematoxylin and eosin. Measure-ments were obtained using an OPTIMAS image analysis sys-tem attached to a BH-2 Olympus microscope. Measurementsare given as range followed in parentheses by mean, standarddeviation and sample size. For measurements of sample sizeequal to two, only the range is provided. All measurements are

in µm unless otherwise stated. Figures were drawn with the aidof a drawing tube on a BX-50 or BH-2 Olympus microscope.Additional specimens were obtained from the following parasitecollections: Coleção Helmintológica do Instituto OswaldoCruz, Rio de Janeiro, Brazil (CHIOC); US National ParasiteCollection, Biosystematics and National Parasite CollectionUnit, USDA, Agricultural Research Service, Beltsville, MD,USA (USNPC); and Harold W. Manter Laboratory, Univer-sity of Nebraska, Lincoln, NB, USA (HWML). Types, para-types and voutcher specimens have been deposited at theColeção Helmintológica do Museu de Zoologia da Universi-dade de São Paulo, SP, Brazil (CHMZUSP).

Material examinedPotamotrygonocestus amazonensis Brooks, Mayes & Thorson,1981: USNPC 76363 (holotype), HWML 21019 (sixparatypes), four specimens from Rio Paraguay, Corumbá,Mato Grosso, Brazil in Potamotrygon motoro, one specimenfrom Rio Apa, Paraguay Basin, Bela Vista, Mato Grosso doSul, Brazil in P. falkneri, two specimens from Lower Amazon,Belém, Pará, Brazil in P. constellata, one specimen fromLower Amazon, Belém, Pará, Brazil in P. motoro, two speci-mens from Upper Rio Negro, c. Barcelos, Amazonas, Brazilin Potamotrygon sp., one specimen from Upper Rio Negro, c.

Table 1 List of the hosts for parasites examined during the present study. Numbers following UFPB refer to the accession numbers for hosts deposited at the Universidade Federal da Paraíba, João Pessoa, Paraíba, Brazil.

Species Localities sampled

Paratrygon aiereba Cachoeira do Ariri, Ilha de Marajó, Pará, Brazil [two males (UFPB 3478) and one female (UFPB 3479)]; Rio Tocantins, Marabá, Pará, Brazil (one female); Rio Negro, Barcelos, Amazonas, Brazil (three females); Rio Negro, Ilha Guariba, Amazonas, Brazil [one male and two females (UFPB 3533–3535)]

Plesiotrygon iwamae Confluence of Paraná Janauacá and Rio Solimões, near Manaus, Amazonas, Brazil [one male (UFPB 3540)]Potamotrygon constellata Cachoeira do Ariri, Ilha de Marajó, Pará, Brazil [11 males (UFPB 3472, 3483, 3518, 3519, 3527, 3529) and 13 females (UFPB 3470, 3473–

3475, 3525, 3526, 3528, 3530)]; Cametá, confluence of Rio Tocantins and Rio Solimões, Cametá, Pará, Brazil (one male), Paraná Janauacá and Rio Solimões, near Manaus, Amazonas, Brazil (one female)

P. falkneri Rio Apa, Bela Vista, Mato Grosso do Sul, Brazil (one male and one?)P. henlei Rio Tocantins, Marabá, Pará, Brazil (five females)P. leopoldi Rio Xingú, Altamira, Pará, Brazil (four males and six females)P. motoro Cachoeira do Ariri, Ilha de Marajó, Pará, Brazil [five males and eight females (UFPB 3467)]; Cametá, confluence of Rio Tocantins and Rio

Solimões, Cametá, Pará, Brazil [one male (UFPB 3522)]; Paraná Janauacá and Rio Solimões, near Manaus, Amazonas Brazil [one male (UFPB 3541) and two females]; Rio Tocantins, Marabá, Pará, Brazil (one male); Iguarapé Corinbaú, Rio Branco, Amazonas, Brazil (one male); Rio Negro, Ilha Guariba, near Barcelos, Amazonas, Brazil (one female); Rio Arirara, Upper Rio Negro, near Barcelos, Amazonas, Brazil (one male); Rio Paraná, Puerto Reconquista, Santa Fé, Argentina [six males and four females (UFBP 3053–3055)]

P. ocellata Cachoeira do Ariri, Ilha de Marajó, Pará, Brazil [one male and one female (UFPB 34671)]P. orbignyi Cachoeira do Ariri, Ilha de Marajó, Pará, Brazil [nine males (UFPB 3469, 3476, 3480–3482, 3515, 3517, 3520, 3531) and two females

(UFPB 3468, 3516)]; Cameta, confluence of Rio Tocantins and Rio Solimões, Cametá, Pará, Brazil [one female (UFPB 3521) and unidentified specimen (UFPB 3523)]; Paraná Janauacá and Rio Solimões, near Manaus, Amazonas, Brazil (one male); Rio Tocantins, Marabá, Pará, Brazil (two females); Rio Branco, Amazonas, Brazil [one female (UFPB 3536)]; Rio Negro, Ilha Guariba, near Barcelos, Amazonas, Brazil [one male (UFPB 3537)]; Rio Arirara, Upper Rio Negro, near Barcelos, Amazonas, Brazil [one male and five females (UFPB 3538–3539)]; Rio Arirara, Upper Rio Negro, near Barcelos, Amazonas, Brazil [one male and five females (UFPB 3538–3539)]

P. schroederi Ilha do Catalão, confluence of Rio Negro and Rio Solimões, near Manaus, Amazonas, Brazil (one male)P. scobina Rio Guamá, Ourém, Pará, Brazil (UFPB 3532); Paraná Janauacá and Rio Solimões near Manaus, Amazonas, Brazil [one female (UFPB 3542)]P. signata Confluence of Rio Poty and Rio Parnaíba, Teresina, Piauí, Brazil (three males and three females) (some specimens are deposited at UFPB)Potamotrygon sp. Rio Negro, Barcelos, Amazonas, Brazil [five males (UFPB 3543) and five females]

F. P. L. Marques et al. • Systematics and phylogeny of Potamotrygonocestus


Barcelos, Amazonas, Brazil in P. orbignyi, one detachedgravid proglottid from Upper Rio Negro, c. Barcelos, Ama-zonas, Brazil in P. motoro, four specimens from Lower RioSolimões, Paraná Janauacá, c. Manaus, Amazonas, Brazil inP. scobina, three specimens from Rio Tocantins, Marabá, Pará,Brazil in P. orbignyi. Potamotrygonocestus magdalenensis Brooks& Thorson, 1976: USNPC 73543 (two paratypes), HWML37546 (two paratypes), D. R. Brooks personal collection (twospecimens). Potamotrygonocestus orinocoensis Brooks, Mayes &Thorson, 1981: USNPC 757714 (two paratypes), HWML21008, 21009 (five paratypes), HWML 34094 (onevoucher), CHIOC 32816a–f (six vouchers). Potamotrygonoces-tus travassosi Rego, 1979: CHIOC 31487a (holotype),CHIOC 31487b and e (two paratypes), 28 specimens fromLower Amazon, Belém, Pará, Brazil in Paratrygon aiereba,one detached gravid proglottid from Lower Rio Solimões,Lago Janauacá, c. Manaus, Amazonas, Brazil in Potamotrygonconstellata, 16 specimens from Lower Rio Solimões, LagoJanauacá, c. Manaus, Amazonas, Brazil in P. motoro. Potamo-trygonocestus sp. 1: three specimens from the confluence ofParaná Janauacá and Rio Solimões, c. Manaus, Amazonas,Brazil in Plesiotrygon iwamae. Potamotrygonocestus sp. 2: fivespecimens from Upper Rio Negro, c. Barcelos, Amazonas,Brazil in Potamotrygon orbignyi, one specimen from UpperRio Negro, c. Barcelos, Amazonas, Brazil in P. motoro, onedetached mature proglottid from Rio Xingu, Altamira, Pará,Brazil in P. leopoldi, two specimens from Paraguay Basin,Puerto Reconquista, Santa Fé, Argentina in P. motoro, onespecimen from Upper Paraguay, Corumbá, Mato Grosso, Brazilin P. motoro. Potamotrygonocestus sp. 3: one immature and fourincomplete specimens, and three detached proglottides fromPraia do Defunto, Rio Negro, c. Barcelos, Amazonas, Brazil inPotamotrygon orbignyi. Potamotrygonocestus sp. 4: threedetached proglottides from Rio Tocantins, Marabá, Pará,Brazil in Potamotrygon henlei. Potamotrygonocestus sp. 5: eightdetached proglottides from Catalão, confluence of RioNegro and Rio Solimões, c. Manaus, Amazonas, Brazil inPotamotrygon schroederi. Pedibothrium globicephalum Linton,1909 USNPC 8995 (three paratypes), USNPC 82045(five vouchers). Pedibothrium lintoni Caira & Pritchard, 1986USNPC 79027 (holotype), USNPC 79028 (two paratypes),USNPC 35972 (two vouchers), and USNPC 82041 (six slides).Pedibothrium maccallumi Caira & Pritchard, 1986 USNPC36011 (holotype). Pedibothrium brevispine Linton, 1909 USNPC9001 (six paratypes) and USNPC 82046 (five vouchers).Pedibothrium longispine Linton, 1909 USNPC 8992 (holo-type), and USNPC 82044 (five vouchers). Pedibothriumkerkmhami (Southwell, 1911) USNPC 82047 (22 vouchers).

Phylogenetic analysisThe phylogenetic analysis was performed using PAUP*(version 4.1.2a; Swofford 1999) using the exhaustive and

branch-and-bound search algorithm and ACCTRAN opti-mization. Multistate transformation series were consideredunordered, characters were equally weighted, and treeswere rooted by specifying Pedibothrium and Pachybothriumas outgroups (see below for the justification of outgroupchoice). The characters for Pedibothrium were obtainedfrom specimens deposited in museum collections and forPachybothrium obtained from Caira & Pritchard (1986).Character distribution was analysed using MACCLADE (version3.0; Maddison & Maddison 1997).

DescriptionsFamily ONCOBOTHRIIDAE Braun, 1900Potamotrygonocestus Brooks & Thorson, 1976

Type species. Potamotrygonocestus magdalenensis Brooks & Thorson,1976.

Type host. Potamotrygon magdalenae (Valenciennes, 1865).

Generic diagnosis. Scolex with four sessile non-septate both-ridia; each with an apical sucker. Hook prongs hollow, eachwith a channel opening to the outside via a single pore ante-riorly adjacent to the base. Cephalic peduncle absent. Scolexand neck bearing microtriches. Strobila acraspedote, hyper-apolytic. Genital pores posterolateral, irregularly alternating.Testes numerous, in two preovarian lateral fields; postvaginaltestes absent. Vas deferens ascending from the cirrus sac tothe level of the anterior third to half of proglottis, recurvedposteriorly to the region of posterior-most testes; recurvedregion glandular. Ovary posterior, bilobed in cross-section.Vagina anterior to cirrus sac. Vitellarian follicles lateral.Uterus medioventral, saccate. Eggs spherical. Parasites ofneotropical freshwater potamotrygonids.Potamotrygonocestus magdalenensis Brooks & Thorson, 1976:Fig. 1A–E.

Holotype. USNPC 73542.

Paratypes. USNPC 73543, HWML 20254.

Type host. Potamotrygon magdalenae (Valenciennes, 1865).

Site of infection. Anterior portion of the spiral valve.

Type locality. Cienaga Rabón, vicinity of San Cristóbal, Bolí-var, Colombia.

Redescription. Measurements based on specimens fromUSNPC 73543 (paratype: one immature specimen and onedetached proglottis), HWML 37546 (vouchers from typelocality: one immature specimen and one detached proglottis),



Fig. 1 A–E. Potamotrygonocestus magdalenensis. —A. Scolex (D. R. Brooks’ personal collection). —B. Hooks (D. R. Brooks’ personal collection).—C. Hook of the paratype (USNPC 73543). —D. Mature proglottis (paratype, USNPC 73543). —E. Detail of the cirrus sac (HWML 37546).Scale bars: A, D, E = 100 µm; B, C = 10 µm.



and two mature specimens from the personal collectionof D. R. Brooks. Strobila acraspedote, hyperapolytic. Imma-ture specimens 1.1–2.2 (1.8 ± 0.5, n = 4) mm long, composedof seven to 17 (11 ± 4, n = 4) proglottides. Scolex 201–330(248 ± 56, n = 4) long, 222–377 (298 ± 64, n = 4) wide, fourbothridia, sessile, non-septate, each with an apical sucker, anda pair of simple hooks at the anterior 10th of the bothridia.Apical sucker 24–48 (32 ± 9, n = 8) in diameter. Scolex, neck,strobila bearing microtriches decreasing in density posteri-orly (Fig. 1A). Bothridia 194–318 (263 ± 56, n = 6) long by116–161 (135 ± 20, n = 6) wide. Hook prongs emerging fromthe middle of the handle, hollow with a channel opening tothe outside via a single pore anteriorly adjacent to the base(Fig. 1B,C). Lateral hooks 36–51 (42 ± 7, n = 4) long, prongs46–63 (54 ± 7, n = 4) long, bases 17–23 (19 ± 3, n = 4) long.Medial hooks 43–79 (55 ± 15, n = 6) long, prongs 43–79(55 ± 15, n = 6) long, bases 14–24 (20 ± 4, n = 6) long. Neck132–231 (186 ± 50, n = 3) long. Terminal immature proglot-tides 518 long by 271 wide; detached mature proglottides1235 long by 302 wide (Fig. 1D). Testes in two longitudinalrows in anterior two thirds of proglottis, 49–98 (78 ±14, n = 15) long by 35–83 (56 ± 16, n = 15) wide, 18–26 (21 ± 3,n = 5) in number; 10–13 (11 ± 1, n = 5) porally, 8–13 (10 ± 2,n = 5) aporally. Vas deferens ascending from the cirrus sac tothe level of the anterior half to third of proglottis, recurvedposteriorly to the region of posterior-most testes; recurvedregion glandular (Fig. 1D). Genital pore at posterior end ofproglottis to 4% of proglottis length from posterior end.Genital atrium absent. Cirrus sac 62–98 long by 48–78 widein mature proglottides, containing spined eversible cirrus(Fig. 1E). Vagina anterior to cirrus sac. Ovary in posteriorthird of proglottis 82–189 (135 ± 54, n = 3) wide; posteriorovarian lobes may or may not be fused. Aporal arm of ovary193–361 (269 ± 85, n = 3) long, poral arm 125–306 (216 ± 90,n = 3) long (Fig. 1D). Uterus indistinct in mature proglotti-des. Vitellarian follicles compact, 11–19 (14 ± 2, n = 10) wide,in two lateral longitudinal rows extending posteriorly tothe level of the ovarian isthmus. Gravid proglottides notobserved.

Remarks. The description of P. magdalenensis by Brooks &Thorson (1976) has been supplemented by Caira & Orringer(1995), who expanded the original description by addinginformation on the distribution and dimensions of microt-riches. In addition, we have also described glandular cellsattached to the vas deferens in the portion that descends pos-teriorly to the region of the most posterior testes (Fig. 1D).Caira & Orringer (1995) illustrated these cells (their fig. 8),but did not comment on them. These glandular cells arefound in all species of Potamotrygonocestus (see below) and weconsider these cells to be a diagnostic feature of the genus(see generic diagnosis).

Potamotrygonocestus amazonensis Brooks, Mayes & Thorson,1981: Figs 2A–G, 3A–D.

Holotype. USNPC 76363.

Paratypes. HWML 21019.

Type host. Potamotrygon orbignyi (Castelnau, 1855).


Type locality. Rio Itacuaí, 5 km south of Atalaia do Norte,Amazonas, Brazil.

Other hosts. Potamotrygon falkneri, P. constellata, P. motoro,Potamotrygon sp. (Upper Rio Negro), and P. scobina.

Other localities. Upper Paraguay Basin, Corumbá, MatoGrosso, Brazil; Rio Tocantins, Marabá, Belém, Pará, Brazil;Rio Apa, mid-Paraguay, Bela Vista, Mato Grosso do Sul,Brazil; Lower Amazon River, Belém, Pará, Brazil; UpperRio Negro, near Barcelos, Amazonas, Brazil; and LowerSolimões, c. Manaus, Amazonas, Brazil (Table 2).

Redescription. Based on the type series, two mature and fiveimmature specimens. Strobila acraspedote, hyperapolytic;immature specimens 1.4–1.9 (1.6 ± 0.2, n = 4) mm long,composed of 10–13 (11 ± 2, n = 3) proglottides; mature spe-cimens 3.2–3.3 mm long, composed of 12–14 proglottides.Scolex 381–423 (399 ± 17, n = 5) long, 199–372 (321 ± 69,n = 5) wide, comprised of four sessile non-septate bothridia,each with an apical sucker and a pair of simple hooks at theanterior 10th of the bothridia (Fig. 3A–G). Apical sucker24–57 (35 ± 15, n = 4) in diameter. Scolex, neck, strobila bear-ing microtriches decreasing in density posteriorly. Bothridia356–417 (389 ± 21, n = 6) long by 180–212 (194 ± 12, n = 6)wide (Fig. 3A). Hook prongs emerging from the middle ofthe handle, hollow with a channel opening to the outside viaa single pore anteriorly adjacent to the base (Fig. 3B–G).Lateral hooks 71–77 long, prongs 69–76 long, bases 25–31long. Medial hooks 75–91 (82 ± 7, n = 6) long, prongs 67–89(80 ± 9, n = 6) long, bases 22–30 (27 ± 3, n = 5) long. Neck97–221 (157 ± 51, n = 4) long. Terminal immature proglot-tides 392–526 (457 ± 68, n = 4) long by 218–281 (256 ± 27,n = 4) wide; mature attached proglottides 651–675 long by285–293 wide (Fig. 4A). Testes in two longitudinal rows inanterior two thirds of proglottis, 50–91 (67 ± 14, n = 10) longby 38–66 (49 ± 10, n = 10) wide, 20–22 (21 ± 1, n = 3) innumber; 10–12 (11 ± 1, n = 3) porally, 10–11 (10 ± 1, n = 3)aporally (Fig. 3A,B). Vas deferens ascending from the cirrussac to the level of the anterior third of proglottis, recurvedposteriorly to the region of posterior-most testes; recurved



Fig. 2 A–G. Potamotrygonocestus amazonensis. —A. Scolex (voucher specimen, CHIOC 32816e). —B. Hooks of the holotype (USNPC76363). —C. Hooks of CHIOC 32816b. —D, E. Hooks of P. amazonensis in Potamotrygon sp. from Upper Rio Negro. —F. Hooks of P. amazonensisin Potamotrygon orbignyi from Rio Tocantins. —G. Hook of voucher specimen (CHIOC 32816e). Scale bars: A = 100 µm; B–G = 10 µm.



Fig. 3 A–D. Potamotrygonocestus amazonensis. —A. Mature proglottis (paratype, HWML 21019). —B. Mature detached proglottid ofspecimen in Potamotrygon orbignyi from Rio Tocantins. —C. Region of ovary of P. amazonensis in Potamotrygon falkneri from Paraguay drainage.—D. Region of cirrus sac (CHIOC 32816a). Scale bars = 100 µm.



Tabl

e 2

Mor

phom

etri

c pa

ram

eter

s (µ

m) f

or P

otam

otry

gono

cestu

s am

azon

ensis

acc

ordi

ng to

hos

t and

geo

grap

hica

l are

a.

Host

/loca

lity

Prog

lott

ides

Sc

olex

Bo

thri

dia

Stro

bila

leng

thSe

gmen

tsLe

ngth

Wid

thLe

ngth

Wid

thSu

cker

dia

met

er

P. m

otor

o133

96–5

293.

736

–44

324–

368.

328

5–30

7.5

300–

341

117.

8–14

8.7

39.4

–47.

6(4

233

± 87

8.2,

n =

4)

(40

± 3,

n =

4)

(349

.3 ±

21.

3, n

= 4

)(2

98.1

± 1

1.7,

n =

3)

(324

± 1

9, n

= 5

)(1

30.8

± 1

1.3,

n =

5)

(44.

4 ±

2.6,

n =

7)

P. fa

lkne

ri2

—>

3134

1.1

223.

430

5.7–

314.

310

9.9–

130.

947

.2P.

con

stel

lata

345

34.9

2033

1.1–

362.

725

0.4–

282.

427

6.2–

332.

513

9.4–

142.

751

.7(2

98.2

± 2

1.6,

n =

5)

(141

.4 ±

1.8

, n =

3)

P. m

otor

o337

78.4

2434

5.1

249.

428

7.2–

288.

213

9.6

38.4

–42

.7Po

tam

otry

gon

sp.4

>13

68.8

>18

328.

2–34

6.4

285.

2–32

1.3

261.

6–30

1.7

140.

7–16

0.6

44–

58.6

(287

.2 ±

15.

7, n

= 7

)(1

49.8

± 7

.9, n

= 7

)(5

2.6

± 4.

7, n

= 8

)P.

orb

giny

i432

38.4

1730

3.7–

325.

332

3.4–

333.

827

9.8–

317.

414

9.2–

174.

250

.5(2

98.9

± 1

3.9,

n =

7)

(163

.7 ±

9.6

, n =

7)

P. m

otor

o4—

——

——

——

P. s

cobi

na5

—28

–30

302.

3–34

3.8

241.

5–28

7.7

240.

3–34

3.8

105.

5–13

9.9

39.3

–42

.3(3

20.1

± 1

9.5,

n =

4)

(256

.2 ±

21.

3, n

= 4

)(2

90.3

± 3

5.2,

n =

8)

(123

.2 ±

12,

n =

8)

(41.

3 ±

1.7,

n =

3)

P. o

rbog

nyi6

4308

.910

417.

4–43

5.6

378.

6–46

3.7

348.

5–39

6.3

183–

245.

440

–70.

5(4

25.9

± 9

.1, n

= 3

)(4

14.3

± 4

4.2,

n =

3)

(375

.4 ±

20.

8, n

= 5

)(2

17.1

± 2

8.1,

n =

5)

(57

± 13

, n =

5)

Host

/loca

lity

Med

ial h

ooks

Late

ral h

ooks

D

etac

hed

mat

ure

prog

lott

id

Hand

lePr

ong

Leng

thHa

ndle

Pron

gLe

ngth

Leng

thW

idth

Gen

ital p

ore

pos

ition

P. m

otor

o126

.2–3

3.1

57.8

–72

53.2

–68

.527

.3–3

0.6

64.3

–72.

762

.1–

69.6

——

—

(30.

62 ±

2.7

, n =

5)

(65.

1 ±

6.3,

n =

5)

(64.

5 ±

6.4,

n =

5)

(28.

8 ±

1.3,

n =

5)

(68.

4 ±

3, n

= 5

)(6

5.4

± 3.

6, n

= 5

)P.

falk

neri

2—

——

32.7

61.7

64.8

1053

.4–1

229.

126

1.9–

473.

114

1.9–

265.

4(1

157.

4 ±

74.7

, n =

4)

(346

.6 ±

89.

7, n

= 4

) (2

09.4

± 5

1.6,

n =

4)

P. c

onst

ella

ta3

25.6

–30.

855

.9–

66.8

63.5

–66

.233

.266

.969

.8—

——

P. m

otor

o3—

——

27.3

–30

.555

.4–

59.6

62.2

–65

.5—

——

Pota

mot

rygo

n sp

.428

.9–3

5.6

55.5

–62

.151

–63

.629

.8–

35.5

52.7

–58.

254

.7–

62.9

962.

1–13

80.2

277.

9–40

9.1

183.

6–25

6.7

(33.

3 ±

2.1,

n =

8)

(58.

6 ±

2.2,

n =

8)

(59.

4 ±

3.8,

n =

8)

(32.

4 ±

2.3,

n =

8)

(56.

2 ±

1.8,

n =

8)

(59.

4 ±

2.9,

n =

8)

(118

0.6

± 19

0.6,

n =

5)

(345

.1 ±

57.

9, n

= 5

)(2

14.9

± 3

2, n

= 5

)P.

orb

giny

i425

.962

.847

.4—

——

1025

.8–1

127.

236

4.8–

512.

635

1.9–

352

(106

7 ±

53.3

, n =

3)

(420

.7 ±

80.

2, n

= 3

)(3

51.9

± 0

.1, n

= 3

)P.

mot

oro4

——

——

——

——

—P.

sco

bina

533

.3–

4169

.3–

86.7

67.6

–83

.337

.3—

——

——

(37.

5 ±

2.5,

n =

10)

(77

± 5.

8, n

= 1

0)(7

5.6

± 4.

3, n

= 1

0)P.

orb

ogny

i631

.6–

35.9

76.5

–83

.667

.6–7

0.4

35.3

–35.

775

.8–

87.6

69.2

–69

.613

84.6

317.

835

.8

(33.

6 ±

2.2,

n =

3)



Host

/loca

lity

Test

es c

ount

sTe

stes

dia

met

erCi

rrus

sac

in d

etac

hed

mat

ure

prog

lott

ides

Ova

ry in

det

ache

d m

atur

e pr

oglo

ttid

es

Prep

oral

Antip

oral

Tota

lLe

ngth

Wid

thLe

ngth

Wid

th P

oral

lobe

Apor

al lo

beW

idth

P. m

otor

o1—

—23

–26

65.3

–75.

249

.3–

69.6

——

380.

1−45

9.8

423.

5–52

0.6

234.

2–26

3.2

(24

± 1,

n =

4)

(71.

2 ±

4.2,

n =

5)

(57.

8 ±

7.7,

n =

5)

P. fa

lkne

ri2

10–1

19–

1219

–22

51.6

–96.

545

.9–

67.4

80.9

–142

.139

.9–

67.4

173.

4–28

9.3

236.

1–33

494

.1–1

68.9

(10

± 1,

n =

4)

(10

± 1,

n =

4)

(20

± 2,

n =

4)

(73

± 13

.2, n

= 2

0)(5

6.2

± 5.

2, n

= 2

0)

(112

.7 ±

26.

6, n

= 4

)(5

3.2

± 12

.2, n

= 4

)(2

25.8

± 5

0.9,

n =

4)

(280

.6 ±

47.

4, n

= 4

)(1

27.1

± 3

1.1,

n =

4)

P. c

onst

ella

ta3

——

21–2

746

.3–

65.5

33.8

–57.

4—

—40

9.7

459.

911

9.5

(25

± 2.

7, n

= 4

)(5

6.5

± 6.

2, n

= 1

0)(4

4.8

± 7.

5, n

= 1

0)P.

mot

oro3

8–10

6–

916

–17

——

——

——

—(9

± 1

, n =

3)

(8 ±

2, n

= 3

)(1

7 ±

1, n

= 3

)Po

tam

otry

gon

sp.4

9–11

9–12

18–2

355

.6–1

29.9

39.7

–115

.898

.6–1

74.8

34.9

–73

142.

9–36

6.6

239.

7–44

2.3

113.

5–18

1.5

(10

± 1,

n =

6)

(10

± 1,

n =

6)

(20

± 2,

n =

6)

(86.

3 ±

20.7

, n =

30)

(7

1.9

± 20

.9, n

= 3

0)(1

40.1

± 2

8.9,

n =

5)

(50.

4 ±

16.1

, n =

5)

(280

.7 ±

83,

n =

5)

(312

.7 ±

84,

n =

5)

(146

.4 ±

30.

7, n

= 5

)P.

orb

giny

i411

–15

11–1

722

–31

66.1

–85.

356

.7–7

4.3

104.

8–11

4.6

46.5

–57.

130

4.5–

370.

732

3.6–

437

173.

2–24

5.9

(13

± 2,

n =

5)

(14

± 2,

n =

5)

(27

± 4,

n =

8)

(76.

5 ±

7.7,

n =

5)

(64.

6 ±

8.1,

n =

5)

(111

.2 ±

5.5

, n =

3)

(52.

5 ±

5.4,

n =

3)

(342

.8 ±

34.

3, n

= 3

)(3

76.1

± 5

7.2,

n =

3)

(198

.9 ±

40.

8, n

= 3

)P.

mot

oro4

1010

2049

.8–7

2.2

33.2

–47

.7—

——

——

(62.

9 ±

9, n

= 5

)(4

1.6

± 6.

4, n

= 5

)P.

sco

bina

5—

——

——

——

——

—P.

orb

ogny

i68–

118–

12

17–2

256

.3–9

7.3

41.8

–92.

272

.775

.826

6–30

424

1–28

215

7–17

2(1

0 ±

1, n

= 1

4)(9

± 1

, n =

14)

(19

± 2,

n =

14)

(74.

9 ±

12.7

, n =

25)

(66.

4 ±

13.4

, n =

25)

(287

± 1

9, n

= 3

)(2

64 ±

21,

n =

3)

(163

± 8

, n =

3)

1 Upp

er P

arag

uay

Basi

n [C

orum

bá, M

ato

Gra

sso,

Bra

zil;

colle

cted

by

Broo

ks &

Am

ato

(199

2)].

2 Mid

-Par

agua

y Ba

sin

(Bel

a Vi

sta,

Mat

o G

ross

o do

Sul

, Bra

zil).

3 Low

er A

maz

on (B

elém

, Par

á, B

razi

l).4 U

pper

Rio

Neg

ro (a

roun

d Ba

rcel

os, A

maz

onas

, Bra

zil).

5 Low

er S

olim

ões

(Par

aná

Jana

uacá

, nea

r Man

aus,

Amaz

onas

, Bra

zil).

6 Rio

Toca

ntin

s (M

arab

á, P

ará,

Bra

zil).

Tabl

e 2

Con

tinue

d



Fig. 4 A–E. Potamotrygonocestus travassosi. —A. Scolex (paratype, CHIOC 31487b). —B, C. Apical portion of the scolex of P. travassosi inParatrygon aiereba from the Lower Amazon. —D, E. Hooks of P. travassosi in P. aiereba from the Lower Amazon. F, G. Potamotrygonocestusorinocoensis. —F. Scolex of P. orinocoensis (paratype, HWML 21009). —G. Hooks of P. orinocoensis (paratype, HWML 21009). Scale bars:A–C, E = 100 µm; D, E, G = 10 µm.



region glandular (Fig. 3A,B). Genital pore 3–8% of proglot-tides’ length from posterior end. Genital atrium shallow ifpresent. Cirrus sac 59–66 long by 38–50 wide in matureproglottides, containing spined eversible cirrus (Fig. 3D).Vagina anterior to the cirrus sac. Ovary in posterior third ofproglottis 139–158 wide. Aporal arm of ovary 219–224 long,poral arm 225–256 long in mature proglottides, posteriorovarian lobes may or may not be fused (Fig. 3A–C). Uterusindistinct in mature proglottides. Vitellaria compact, 11–19(14 ± 2, n = 10) wide, in two lateral longitudinal rows. Gravidproglottides not observed. Additional meristic and morpho-metric attributes of P. amazonensis from other localities andhosts are given in Table 2.

Remarks. Potamotrygonocestus amazonensis resembles P.magdalenensis in having hook prongs emerging from themiddle of the handle and a genital pore posterior to the ovarianisthmus. However, P. amazonensis differs from P. magdalenensisin possessing longer bothridia (380–423 vs. 205–330),longer bothridial hooks (lateral hooks 71–77 vs. 26–51 andmedial hooks 75–91 vs. 43–78), and in having a shallow gen-ital atrium rather than lacking one. Brooks et al. (1981) sug-gested that P. amazonensis also differed from P. magdalenensisin having follicular rather than compact vitellaria. Re-examination of the type series for both species, in addition to thespecimens collected in this study, revealed that the morphol-ogy of the vitellaria is dependent on the development of theproglottis. In general, both species have compact vitellaria.Vitellaria that appear more follicular can usually be observedin proglottides at later stages of development.

In the original description of P. magdalenensis, Brooks &Thorson (1976) provided an illustration of a detachedproglottis in which the genital pore was found in the extremeposterior margin of the proglottis (their Fig. 4; Fig. 2A ofthe present study). Re-examination of the type series ofP. magdalenensis indicated that the position of the genital porecan vary from the extreme posterior end of the proglottis toup to 4% of the proglottides’ length from its posterior mar-gin. The position of the genital pore in the type series ofP. amazonensis ranges from 3 to 8% of the proglottis lengthfrom the posterior margin, showing some degree of overlapwith P. magdalenensis. However, the extreme distal position ofthe genital pore observed in most specimens of P. magdalen-ensis was not observed in specimens of P. amazonensis. Amongpopulations of P. amazonensis sampled in this study (Table 2),the position of the genital pore showed a considerable degreeof variability. Genital pore position can range from as low as3–8% of proglottis length from the posterior margin, as inthe population in Potamotrygon orbignyi (type series) fromthe Upper Solimões tributaries, to up to 25% in specimens inP. constellata from the Lower Amazon. However, this lattercondition, observed in only two specimens of P. amazonensis

from Potamotrygon constellata, is rather unusual, as in mostof the specimens collected, the position of the genital poreranged from 9 to 18% of the proglottis length from theposterior end. This is the only character that showed greatvariability among the populations sampled. No othermorphological, morphometric, or meristic character (seeTable 2) seemed to have covariation with other attributesobserved in the position of the genital pore. Thus, we con-sider the pattern observed for the position of the genital poreto be intrapopulational variation.

Table 2 shows that specimens of P. amazonensis inhabitingsix different host species for six distinct localities hadconcise morphometric and meristic attributes. Charactershistorically used in the taxonomy of this group, such asstrobilar length, scolex, hooks and proglottid dimensions, didnot deviate greatly among populations. The only characterthat showed a gap among populations was the number of seg-ments and some scolex dimensions. For instance, specimensof P. amazonensis collected in Potamotrygon motoro from theUpper Paraguay Basin, Corumbá, Mato Grosso, Brazil pos-sessed 36–44 segments, whereas the remaining specimenshad between 17 and 30 proglottides. However, a single matureworm collected in P. orbignyi from Rio Tocantins had 10segments. Also, specimens collected in P. orbignyi from RioTocantins had larger scolex dimensions than those fromother localities and hosts (Table 2). We assume that thesediscrepancies might be related to either the small sample sizeor an age factor, as all other characters for this populationseemed to overlap with those found in other populations(Table 2).Potamotrygonocestus travassosi Rego, 1979: Figs 4A–G, 5A,B,6A–C.

Synonym. Potamotrygonocestus orinocoensis Brooks, Mayes &Thorson, 1981.

Holotype. CHIOC 31487a.

Paratypes. CHIOC 31487b and 31487e.

Type host. Potamotrygon orbignyi (Castelnau, 1855) (originallyrecorded as Paratrygon hystrix [sic], but see remarks).

Site of infection. Spiral valve.

Type locality. Amazon River, Maicuru, Pará, Brazil.

Other hosts. Paratrygon aiereba, Potamotrygon constellata, andP. motoro.

Other localities. Lower Amazon River, Belém, Pará, Brazil;Paraná Janauacá, c. Manaus, Amazonas, Brazil.



Fig. 5 A–C. —A. Undifferentiated juvenile of Potamotrygonocestus travassosi. —B. Detached mature proglottis of P. orinocoensis (paratype,USNPC 75714). —C. Mature proglottis of P. travassosi in Paratrygon aiereba from the Lower Amazon. Scale bars = 100 µm.



Fig. 6 A–C. —A. Detail of the male reproductive system of Potamotrygonocestus travassosi. —B. Ovary region (paratype of P. orinocoensis, USNPC75714). —C. Ovary region of P. travassosi. Scale bars = 100 µm.



Redescription. Measurements based on paratype series: twoincomplete specimens. Strobila acraspedote, hyperapolytic.Scolex 319 long by 338 wide, comprising four sessile non-septate bothridia, each with an apical sucker, and a pair ofsimple hooks at the anterior quarter of the bothridia. Apicalsucker 51–77 (67 ± 11, n = 4) long by 105–116 (111 ± 6,n = 4) wide. Scolex, neck, strobila bearing microtrichesdecreasing in density posteriorly (Fig. 4A). Bothridia 202–221 (211 ± 9, n = 4) long by 160–172 (166 ± 5, n = 4) wide.Hooks asymmetrical, prongs hollow with a channel openingto the outside via a single pore anteriorly adjacent to the base,hook prong emerging from the posterior end of the handle.Lateral hooks 127–131 long, prongs 128–130 long, bases59–60 long. Medial hooks 117–121 long, prongs 93–98 long,bases 63–65 long. Neck 155 long. Immature proglottidesinitially wider than long, becoming longer than wide. Matureproglottides not observed. Testes in two longitudinal rowsin anterior two thirds of proglottis, 26–27 (26 ± 1, n = 2) innumber; 13 (n = 2) porally, 12–14 antiporally.

Extended description. Measurements based on new materialinhabiting the type host: two complete specimens and oneincomplete specimen. Strobila acraspedote, hyperapolytic,immature specimens 1.5–1.7 (1.6 ± 0.2, n = 2) mm long,composed of six to nine (7 ± 2, n = 3) proglottides; maturespecimens 2.7 mm long, composed of six proglottides. Scolex177–265 (223 ± 44, n = 3) long by 226–278 (257 ± 23, n = 4)wide, comprised of four sessile non-septate bothridia, eachwith an apical sucker, and a pair of simple hooks at the anteriorquarter of the bothridia. Apical sucker 35–63 (46 ± 11, n = 7)long by 53–81 (70 ± 11, n = 7) wide. Scolex, neck, strobilabearing microtriches decreasing in density posteriorly. Both-ridia 127–229 (160 ± 37, n = 9) long by 92–162 (130 ± 20,n = 10) wide. Hooks asymmetrical, prongs emerging fromthe posterior end of the handle, hollow with a channel openingto the outside via a single pore anteriorly adjacent to the base.Lateral hooks 80–105 (87 ± 7, n = 12) long, prongs 66–93(75 ± 7, n = 11) long, bases 30–45 (36 ± 4, n = 12) long.Medial hooks 64–88 (73 ± 8, n = 7) long, prongs 48–78(57 ± 13, n = 6) long, bases 31–43 (37 ± 4, n = 8) long. Neck142–253 (185 ± 59, n = 3) long. Immature proglottidesinitially wider than long, becoming longer than wide. Matureattached proglottides 994 long by 240 wide. Testes in twolongitudinal rows in anterior two thirds of proglottis, 51–58(55 ± 3, n = 5) long by 39–45 (42 ± 2, n = 5) wide, 24 innumber, 10 porally, 14 aporally. Vas deferens ascendingfrom the cirrus sac to the level of the anterior half to third ofproglottis, recurved posteriorly to the region of posterior-mosttestes; glandular region at proximal region of the deferens,immediately after the area where the vas deferens andsperm ducts join (Fig. 6A). Cirrus sac 109 long by 56 wide, inposterior third of proglottis, containing spined eversible

cirrus. Genital pore 32% of proglottis length from anteriorend, at the level of or slightly anterior to the ovarian isthmus.Genital atrium shallow. Vagina anterior to the cirrus sac.Ovary in posterior third of proglottis, 147 wide. Aporal armof ovary 327 long, poral arm 345 long in mature attachedproglottides; inverted ‘A’ or theta-shaped. Uterus indistinctin mature proglottides. Uterine duct joining uterus near theposterior end. Vitellaria compact, 11–18 (15 ± 3, n = 5) wide,in two lateral longitudinal rows which may or may not overlapthe cirrus sac. Gravid proglottides not observed. Additionalmeristic and morphometric attributes of P. travassosi are givenin Table 3.

Remarks. This redescription of Potamotrygonocestus travassosibased on the type specimens used by Rego (1979) eliminatesthe confusion stemming from the inadvertent inclusion of aproglottis of Paroncomegas araya in the original description(Rego 1979: 882, fig. 6), as noted by Brooks et al. (1981). Thematerial used by Rego (1979) included a vial (CHIOC 26499)containing several specimens of P. araya and two slides(CHIOC 31487c, d) containing proglottides of P. araya.However, the holotype (CHIOC 31487a) and two paratypes(CHIOC 31487b, e) allowed us to recognize P. travassosi as avalid species.

Examination of the type series of Potamotrygonocestusorinocoensis revealed that this species is a junior synonym ofP. travassosi. Brooks et al. (1981) described P. orinocoensisinhabiting Potamotrygon orbignyi from the delta of Rio Orinoco[host identified as P. reticulatus in the original description andlater corrected by Brooks & Amato (1992) after Rosa (1985)].As mentioned above, they pointed out that one of theillustrations provided by Rego (1979: fig. 5) for a bothridialhook suggested that P. orinocoensis and P. travassosi sharedsome resemblance. Brooks et al. (1981) also suggested thatP. orinocoensis closely resembles P. magdalenensis in possessingcompact vitellaria, and in lacking a genital atrium. However,full comparisons among these three species could not havebeen made by the authors, as in their publication they notonly acknowledged not having examined specimens ofP. travassosi (Brooks et al. 1981: 48), but also because the illus-tration provided by Rego (1979) for the proglottis belongedto a trypanorhynch.

Examination of the type series of P. travassosi andP. orinocoensis revealed few differences between samples, noneof which we consider sufficient to recognize two distinctspecies, as they are not supported by material from sub-sequent collections. For instance, the handles of the medialand lateral hooks are larger in specimens of the type seriesof P. travassosi (63–65 and 59–60, respectively) than thoseof P. orinocoensis (22–48 and 26–45, respectively). The typeseries of P. travassosi also possesses longer medial and lateralhook handles compared with the specimens used in this



Tabl

e 3

Mor

phom

etri

c pa

ram

eter

s fo

r tw

o sp

ecie

s of

Pot

amot

rygo

noce

stus a

ccor

ding

to h

ost a

nd g

eogr

aphi

cal a

rea.

Spec

ies/

loca

lity/

host

Imm

atur

e sp

ecim

ens

Mat

ure

spec

imen

sSc

olex

Both

ridi

aSu

cker

dim

ensi

on

Size

(mm

)Se

gmen

tsSi

ze (m

m)

Segm

ents

Leng

thW

idth

Leng

thW

idth

Leng

thW

idth

P. tr

avas

sosi

1V1.

4–1.

7 7–

8—

—22

3.8–

316.

118

1.1–

267.

914

7.5–

190.

684

.5–1

27.6

46.6

–77.

746

.9–

62.5

(1.6

± 0

.1, n

= 3

)(7

± 1

, n =

3)

(273

.9 ±

34.

5, n

= 5

)(2

11 ±

33.

7, n

= 5

)(1

73.3

± 1

5.2,

n =

9)

(103

.6 ±

16.

2, n

= 8

)(6

0.4

± 10

.3, n

= 1

0)(5

6.3

± 6,

n =

8)

P. tr

avas

sosi

2I1.

4–2.

2 4–

8 2.

3–3.

66–

1019

7.8–

333.

423

3.9–

338.

314

3.3–

242.

290

.1–1

64.6

20.4

–90.

853

.5–1

06.9

(1.8

± 0

.4, n

= 1

1)(6

± 2

, n =

14)

(3.1

± 0

.5, n

= 1

0)(7

± 1

, n =

10)

(249

± 3

1.4,

n =

27)

(278

.5 ±

28,

n =

28)

(181

.8 ±

24.

5, n

= 5

5)(1

32.7

± 1

7.1,

n =

55)

(52.

1 ±

16.7

, n =

22)

(83.

7 ±

11.6

, n =

43)

P. tr

avas

sosi

3II

——

——

——

——

——

P. tr

avas

sosi

3IV

1–2.

3 9–

141.

7–1.

88–

1324

0.5–

312.

421

4.1–

322.

614

1.9–

215.

690

.2–1

56.3

33–8

622

.8–1

52.2

(1.7

± 0

.4, n

= 1

2)(1

1 ±

1, n

= 1

2)(1

.8 ±

0.0

6, n

= 3

)(1

0 ±

2, n

= 3

)(2

76.4

± 2

2.4,

n =

16)

(264

.2 ±

37.

6, n

= 1

6)(1

82.6

± 1

9.5,

n =

45)

(122

.3 ±

18.

1, n

= 4

2)(6

0.1

± 17

.3, n

= 3

2)(6

1.7

± 19

.2, n

= 4

0)P.

fitz

gera

ldae

4V3–

624

–37

——

222.

1–24

826

5–30

5.3

144.

6–17

6.3

100.

7–15

2.4

52.1

–57.

138

.4–7

7.7

(4.5

± 1

.1, n

= 7

)(3

1 ±

5, n

= 7

)(2

33.2

± 9

.7, n

= 5

)(2

91.4

± 1

5.5,

n =

5)

(162

.9 ±

10,

n =

12)

(130

.6 ±

14.

7, n

= 1

2)(5

4.4

± 2.

5, n

= 3

)(6

1.9

± 12

.4, n

= 9

)P.

fitz

gera

ldae

4IV

2.6

15—

—18

7.7

243.

912

0.8–

139.

4(1

29.5

± 9

.4, n

= 3

)93

.7–9

7.5

(95.

2 ±

2, n

= 3

)—

41.6

–53.

7(4

6.9

± 6.

2, n

= 3

)

P. fi

tzge

rald

ae5I

II—

——

——

——

——

—P.

fitz

gera

ldae

6IV

——

——

430.

4–47

4.3

423.

8–43

4.7

251–

289.

418

6–24

1.5

83.1

–122

.611

7–13

9(2

74.6

± 1

3, n

= 6

)(2

04.2

± 1

9.4,

n =

6)

(104

.3 ±

16,

n =

7)

(125

.5 ±

9.2

,n =

7)

P. fi

tzge

rald

ae7I

V4.

17

——

432.

2—

268.

713

3.7

90.8

97.8

Spec

ies/

loca

lity/

host

Med

ial h

ook

Late

ral h

ook

Det

ache

d m

atur

e pr

oglo

ttid

es

Hand

lePr

ong

Leng

thHa

ndle

Pron

gLe

ngth

Leng

thW

idth

Gen

ital p

ore

P. tr

avas

sosi

1V30

–48

55–

9167

–104

26.3

–45

.278

.2–1

09.3

71.3

–125

912.

9–96

0.8

259.

1–28

1.1

266.

6–31

5

(40

± 5,

n =

15)

(72

± 12

, n =

15)

(8

6 ±

10, n

= 1

5)(3

5.1

± 5.

9, n

= 1

3)(9

3.4

± 11

.1, n

= 1

3)(9

8 ±

17.6

, n =

13)

(937

.6 ±

24,

n =

3)

(268

.5 ±

11.

3, n

= 3

)(2

90.1

± 2

4.2,

n =

3)

P. tr

avas

sosi

2I29

.9–

54.2

47.6

–88

.360

–105

30.8

–50.

261

.6–1

18.6

70.7

–112

.1—

——

(44.

6 ±

4.4,

n =

55)

(70.

2 ±

7, n

= 5

1)(8

9 ±

7, n

= 5

3)(4

1.2

± 4.

1, n

= 5

3)(9

3.7

± 9.

7, n

= 5

5)(9

6.1

± 8.

8, n

= 4

8)P.

trav

asso

si3I

I—

——

——

——

——

P. tr

avas

sosi

3IV

32.9

–50.

972

.2–9

9.3

83.9

–112

.339

–51.

792

.6–1

25.1

92–1

32.1

726.

8–16

09.7

231.

6–32

0.8

194.

7–38

3(4

4.9

± 4.

5, n

= 3

1)(8

4.6

± 6.

7, n

= 3

1)(1

00.8

± 6

.7, n

= 3

1)(4

4.4

± 3.

4, n

= 2

5)(1

07.3

± 8

.9, n

= 2

7)(1

10.2

± 8

, n =

23)

P. fi

tzge

rald

ae4V

39.3

–54

72.3

–98.

782

.6–1

00.7

38.6

–53.

710

2.3–

145.

796

.1–1

28.5

1423

.9–1

995.

232

5–72

9.7

262.

7–62

1.3

(46.

8 ±

3.3,

n =

18)

(88.

1 ±

7.8,

n =

16)

(9

4.8

± 5.

1, n

= 1

5)

(46

± 4.

4, n

= 1

8)(1

30.4

± 1

1.8,

n =

18)

(116

2.2

± 9.

9, n

= 1

8)(1

713.

6 ±

286.

9, n

= 4

)(4

58.1

± 1

90.6

, n =

4)

(463

.3 ±

179

.1, n

= 4

)P.

fitz

gera

ldae

4IV

35.8

–42

.270

.5–

83.6

72.1

–86.

544

–45

.310

3–11

3.9

96.3

–101

.2—

——

(39.

9 ±

3.6,

n =

3)

(77.

5 ±

6.6,

n =

3)

(81.

4 ±

8.1,

n =

3)

(44.

8 ±

0.7,

n =

3)

(107

.1 ±

5.9

, n =

3)

(98.

8 ±

2.4,

n =

3)

P. fi

tzge

rald

ae5I

II—

——

——

—18

76.3

299.

447

1.1

P. fi

tzge

rald

ae6I

V60

.8–7

1.9

85.4

–94.

711

6.8–

132.

456

.1–6

2.1

141.

1–15

3.8

130.

8–14

5.2

——

—(6

7.8

± 4,

n =

6)

(89.

4 ±

4.8,

n =

3)

(127

.4 ±

5, n

= 7

)(5

9.3

± 2.

2, n

= 5

)(1

47.6

± 5

.6, n

= 4

)(1

37.1

2 ±

6, n

= 5

)P.

fitz

gera

ldae

7IV

78.7

87.5

139.

463

.614

8.4

141.

2—

——



Spec

ies/

loca

lity/

host

Test

es c

ount

sTe

stes

dia

met

erCi

rrus

sac

in d

etac

hed

mat

ure

prog

lott

idO

vary

in d

etac

hed

mat

ure

prog

lott

id

Prep

oral

Antip

oral

Tota

lLe

ngth

Wid

thLe

ngth

Wid

thPo

ral l

obe

Apor

al lo

beW

idth

P. tr

avas

sosi

1V10

–11

10–1

220

–23

57.4

–66

.448

.5–5

6.6

103.

6–12

4.1

39.2

–44

.827

12.2

–308

.527

2.3–

322.

712

4.2–

129.

6(1

1 ±

1, n

= 3

)(1

1 ±

1, n

= 3

)(2

2 ±

2, n

= 3

) (6

1.4

± 4,

n =

5)

(52.

9 ±

4, n

= 5

) (1

11.7

± 1

0.9,

n =

3)

(42.

1 ±

2.8,

n =

3)

(284

.3 ±

20.

9, n

= 3

)(2

94.1

± 2

5.9,

n =

3)

(127

± 2

.7, n

= 3

)P.

trav

asso

si2I

10–1

410

–16

20–3

047

.5–

83.1

9.4–

67.7

122.

2–25

4.7

33–5

05.5

——

—(1

2 ±

1, n

= 2

7)(1

2 ±

2, n

= 2

7)(2

4 ±

3, n

= 2

7)(6

2.9

± 7.

3, n

= 7

0)(4

9 ±

8.2,

n =

70)

(190

.6 ±

52.

5, n

= 7

)(3

00.9

± 1

85.9

, n =

7)

P. tr

avas

sosi

3II

1211

2311

0.2–

140.

883

.5–9

3.9

——

——

—(1

22.2

± 1

3.3,

n =

5)

(87.

8 ±

4.3,

n =

5)

P. tr

avas

sosi

3IV

9–12

9–15

18–2

744

.8–1

0334

.1–

96.4

89.5

–109

.921

.6–

4116

6.1–

381.

417

3–40

0.1

105.

4–14

8.1

(10

± 1,

n =

29)

(11

± 2,

n =

29)

(21

± 2,

n =

29)

(65.

7 ±

13.8

, n =

45)

(55.

2 ±

14.2

, n =

45)

P. fi

tzge

rald

ae4V

12–2

311

–22

23–

4450

.2–1

03.7

31.3

–80

.268

.2–1

92.5

34.4

–102

.324

2.4–

411.

821

8.6–

518.

212

8.5–

187.

5(1

0 ±

4, n

= 1

0)(1

5 ±

3, n

= 1

0)(3

1 ±

7, n

= 1

0)(7

56 ±

14.

7, n

= 2

0)(5

6.7

± 11

.4, n

= 2

0)

(136

± 5

6.7,

n =

5)

(62.

7 ±

26.4

, n =

5)

(341

.2 ±

88.

1, n

= 3

(411

± 1

67, n

= 3

)(1

52 ±

31.

3, n

= 3

)P.

fitz

gera

ldae

4IV

1819

3740

.9–4

831

–34

——

——

—(4

5.1

± 2.

6, n

= 5

)(3

2.6

± 1.

1, n

= 5

)P.

fitz

gera

ldae

5III

1818

3250

.8–6

7.9

35.8

–46

.812

0.1

38.9

315.

640

5.3

102.

3(5

7 ±

6.5,

n =

5)

(42.

1 ±

4.5,

n =

5)

P. fi

tzge

rald

ae6I

V17

–23

17–2

434

–46

52.7

–65

.835

–52.

815

5.3

56.1

——

—(2

0 ±

3, n

= 4

)(2

1 ±

3, n

= 4

)(4

1 ±

6, n

= 4

)(6

1 ±

4.2,

n =

10)

(43.

8 ±

6.4,

n =

10)

P. fi

tzge

rald

ae7I

V—

——

——

——

——

—

1 Orin

oco

(type

ser

ies

of P

. orin

ocoe

nsis)

. 2 Low

er A

maz

on (B

elém

, Par

á, B

razi

l). 3 Lo

wer

Rio

Sol

imõe

s (M

anau

s, Am

azon

as, B

razi

l). 4 U

pper

Rio

Neg

ro (a

roun

d Ba

rcel

os, A

maz

onas

, Bra

zil).

5 Rio

Xing

u (A

ltam

ira, P

ará,

Bra

zil).

6 Low

er P

aran

á (P

uert

o Re

conq

uist

a, S

anta

Fé,

Arg

entin

a). 7 U

pper

Par

agua

y (C

orum

bá, M

ato

Gro

sso,

Bra

zil).

Hos

ts: I Pa

ratr

ygo

n a

iere

ba;

II Pota

mo

tryg

on

co

nst

ella

ta; III

P. le

op

old

i; IVP.

mo

toro

; V P. o

rbig

nyi

.

Tabl

e 3

Con

tinue

d



redescription which were collected from the type host in thesame geographical area (see above) of the type series, andcompared with specimens collected from other hosts fromdifferent localities (Table 3). The type material used in thepresent description is restricted to two incomplete specimens(as part of the paratypes were proglottides of Paroncomegas)which suggest caution when differentiating the two speciesbased on those characteristics.

Another difference between the type series of P. travassosiand P. orinocoensis is in the morphology of the scolex. Rego(1979: 883) noticed that in P. travassosi the ‘accessory suckerwas not observed, although it does probably exist’ (translationby FPLM). In the specimens of the type series of P. orinocoensis,the apical sucker is well defined (cf. Fig. 4A,F). In fact, re-examination of the paratype of P. travassosi (CHIOC 31487b)revealed that the apical sucker is not discernible (Fig. 4A).After examining a considerable number of specimens, whichwe attributed to P. travassosi, we concluded that the lack ofapical sucker, observed in the type series of P. travassosi,might be an artefact of fixation. We were unable to collectanything that resembled the paratype of P. travassosi,even in the type host in regions close to the type locality.However, some intermediate stages between the conditionobserved in P. travassosi and that of the type series ofP. orinocoensis were observed in a few specimens from variouslocalities (Fig. 4B,C). Hence, we consider this characterinsufficient to justify the recognition of two species. In fact,morphometric and meristic attributes for P. travassosicollected in four different host species from three differentlocalities overlap greatly (Table 3) suggesting some degree ofvariation among populations, although they seemed to becontinuous.

Potamotrygonocestus travassosi resembles P. amazonensis andP. magdalenensis in having compact vitellaria and similarnumbers of testes (18–30, 16–31, and 18–26, respectively).However, P. travassosi differs from these two species in havingasymmetrical hooks at the anterior quarter of the bothridiarather than symmetrical ones at the anterior 10th of thebothridia, hook prongs emerging from the posterior end ofthe handle rather than at the middle, and in having the genitalpore at the level of, or anterior to, the ovarian isthmus ratherthan posterior to it.

Brooks et al. (1981) described P. orinocoensis as possessing aunique theta-shaped ovary (Figs 5B, 6B). This character showedsome degree of variability. In attached mature proglottides,the ovary tends to have an inverted ‘A’ shape, in which theanterior poral ovarian lobe may be medially displaced bythe cirrus sac (Fig. 5C). The theta-shaped ovary (Fig. 6B) isgenerally found in detached mature or gravid proglottides,but such proglottides may occasionally possess an inverted‘A’-shaped ovary.Potamotrygonocestus chaoi n. sp.: Fig. 7A–D.

Holotype. MZUSP 5837.

Paratypes. MZUSP 5838–5844.

Type host. Plesiotrygon iwamae Rosa, Castello & Thorson,1987.


Type locality. Confluence of Paraná Janauacá and RioSolimões, c. Manaus, Amazonas, Brazil.

Etymology. This species is named after Labbish Chao, Uni-versidade do Amazonas, Manaus, Amazonas, Brazil.

Description. Based on three incomplete specimens and 26detached proglottides. Strobila acraspedote, hyperapolytic,composed of more than 44 to more than 55 proglottides. Thespecimens collected were broken, suggesting that completespecimens have more proglottides than reported herein.Scolex 494–534 (509 ± 22, n = 3) long by 568–627 (600 ± 30,n = 3) wide, comprised of four sessile non-septate bothridia,each with an apical sucker, and a pair of simple hooks at theanterior third of the proglottides (Fig. 7A). Apical sucker115–150 (136 ± 13, n = 6) long by 159–212 (183 ± 13, n = 11)wide. Scolex, neck, strobila bearing microtriches decreasingin density posteriorly. Bothridia 278–329 (299 ± 13, n = 10)long by 216–309 (267 ± 25, n = 10) wide. Hooks asymmetrical,prongs emerging from the posterior end of the handle,with a channel opening to the outside via a single pore ante-riorly adjacent to the base (Fig. 7C). Lateral hooks 126–154(145 ± 9, n = 10) long, prongs 120–138 (132 ± 6, n = 10) long,bases 63–78 (72 ± 5, n = 10) long. Medial hooks 134–152(143 ± 5, n = 11) long, prongs 89–107 (101 ± 5, n = 11) long,bases 77–87 (83 ± 2, n = 11) long. Neck 950 long. Immatureproglottides initially wider than long, becoming longer thanwide. Detached mature proglottides 1869–2504 (2112 ± 244,n = 8) long by 432–603 (506 ± 57, n = 8) wide; detachedgravid proglottides 2110–5432 (3492 ± 1043, n = 10) long by411–1323 (645 ± 264, n = 10) wide (Fig. 7B) and detachedpostgravid proglottides 4317–4723 long by 499–536 wide.Testes in two longitudinal rows in anterior two thirds ofproglottis, 54–144 (87 ± 21, n = 80) long by 47–114 (69 ± 15,n = 80) wide, 64–107 (87 ± 17, n = 20) in number; 33–63(45 ± 8, n = 20) porally, 29–53 (41 ± 6, n = 20) aporally(Fig. 7B). Vas deferens ascending from the cirrus sac to thelevel of the anterior third of proglottis, recurved posteriorlyto the region of posterior-most testes; recurved region glan-dular. Cirrus sac in posterior quarter of proglottis containingspined eversible cirrus, 137–194 (162 ± 22, n = 8) long by50–64 (60 ± 5, n = 8) wide in detached mature proglottides;124–245 (178 ± 37, n = 10) long by 59–93 (78 ± 11, n = 10)



Fig. 7 A–D. Potamotrygonocestus chaoi n. sp. —A. Scolex. —B. Gravid detached proglottis. —C. Bothridial hooks. —D. Cirrus sac region. Scalebars: A, B, D = 100 µm; C = 50 µm.



wide in detached gravid proglottides (Fig. 7D); and 193–218long by 107–108 wide in detached postgravid proglottides.Genital pore 18–28% of proglottis length from posteriorend. Genital atrium absent. Vagina anterior to the cirrus sac.Ovary inverted ‘A’ shape, posterior ovarian lobes not fused;in posterior third of proglottis, 209–328 (267 ± 44, n = 8)wide at the isthmus region. Aporal arm of ovary 387–588(491 ± 75, n = 8) long, poral arm 298–541 (439 ± 83, n = 8)long in detached mature proglottides; and 246–579 (362 ± 94,n = 10) wide, aporal arm 575–1361 (858 ± 241, n = 10) long,poral arm 424–1212 (739 ± 244, n = 10) long in detachedgravid proglottides. Uterus indistinct in mature proglottides.Vitellaria compact 14–56 (27 ± 8, n = 118) wide, in two lat-eral longitudinal rows overlapping the cirrus sac (Fig. 7D).

Remarks. Potamotrygonocestus chaoi is only known from Plesi-otrygon iwamae. Indeed, it is the only cestode that has beenreported from this species of freshwater potamotrygonid.The new species most closely resembles P. travassosi inpossessing asymmetrical hooks at the anterior third toquarter of the proglottides and hook prongs emerging fromthe posterior end of the handle. However, P. chaoi differsfrom P. travassosi in possessing a longer scolex (494–534 vs.199–474) and a greater number of testes (64–107 vs. 20–30).Potamotrygonocestus chaoi differs from P. amazonensis andP. magdalenensis in the symmetry of bothridial hooks(asymmetrical vs. symmetrical), the position of the bothridialhooks (at the anterior third rather than at the anterior 10thof the bothridia), insertion of the hook prongs (at the pos-terior end of the handle rather than at the middle), and theposition of the genital pore (anterior to ovarian isthmusrather than posterior).Potamotrygonocestus fitzgeraldae n. sp.: Figs 8A–C, 9A–D.



Type host. Paratrygon aiereba (Müller & Henle, 1841).

Type locality. Upper Rio Negro, near Barcelos, Amazonas, Brazil.

Other hosts. Potamotrygon leopoldi, P. motoro, and P. orbignyi.

Other localities. Rio Xingu, Altamira, Pará, Brazil; LowerParaguay, Puerto Reconquista, Santa Fé, Argentina; UpperParaguay, Corumbá, Mato Grosso, Brazil.


Etymology. This species is named in honour of one of thegreatest jazz singers, Ms Ella Fitzgerald.

Description. Based on 11 mature and 18 immature completespecimens, 10 incomplete specimens, and 47 detached pro-glottides. Strobila acraspedote, hyperapolytic, immatureproglottides 1–4 (2.4 ± 0.8, n = 15) mm long, composed offive to 23 (16 ± 5, n = 15) proglottides; mature specimens1.6–4.1 (2.6 ± 0.7, n = 11) mm long, composed of 10–19(15 ± 3, n = 10) proglottides. Scolex 108–271 (221 ± 29,n = 31) long, 126–325 (250 ± 34, n = 30) wide, comprised offour sessile non-septate bothridia, each with an apical sucker,and a pair of simple hooks at the anterior quarter of thebothridia. Apical sucker 24–77 (43 ± 9, n = 57) long by 38–77(55 ± 8, n = 83) wide. Scolex, neck, strobila bearing microt-riches decreasing in density posteriorly (Fig. 8A). Bothridia112–188 (153 ± 17, n = 82) long by 74–148 (112 ± 13, n = 93)wide. Hooks asymmetrical, prongs emerging from theposterior end of the handle, hollow with a channel openingto the outside via a single pore anteriorly adjacent to thebase (Fig. 8C). Lateral hooks 80–137 (100 ± 10, n = 74) long,prongs 85–128 (108 ± 10, n = 71) long, bases 33–52 (43 ±4, n = 75) long. Medial hooks 52–104 (80 ± 9, n = 97) long,prongs 60–95 (75 ± 8, n = 98) long, bases 31–49 (40 ± 4,n = 99) long. Neck 84–236 (155 ± 35, n = 19) long. Terminalimmature proglottides 389–852 (647 ± 122, n = 15) long by165–334 (220 ± 47, n = 15) wide; mature attached proglotti-des 691–872 (768 ± 60, n = 6) long by 152–310 (234 ± 59,n = 6) wide (Fig. 9A); detached mature proglottides1105–2988 (1796 ± 517, n = 30) long by 222–581 (357 ± 81,n = 30) wide (Fig. 8B); detached gravid proglottides1317–2681 (2070 ± 480, n = 8) long by 306–719 (508 ± 129,n = 8) wide, and detached postgravid proglottides 2970 longby 656 wide. Testes in two longitudinal rows in anterior twothirds of proglottis (Figs 8B, 9A), 24–103 (67 ± 17, n = 193)long by 17–84 (50 ± 13, n = 193) wide, 20–48 (34 ± 6, n = 69)in number; 10–24 (17 ± 3, n = 68) porally, 10–24 (17 ± 3,n = 68) aporally. Vas deferens ascending from the cirrus sac tothe level of the anterior third of proglottis, recurved posteri-orly to the region of posterior-most testes; recurved regionglandular. Cirrus sac in posterior third to quarter of proglot-tis, containing spined eversible cirrus (Fig. 9B); 80–115(98 ± 15, n = 6) long by 19–43 (33 ± 9, n = 6) wide in matureattached proglottides; 89–199 (131 ± 31, n = 28) long by32–68 (48 ± 8, n = 28) wide; 114–152 (133 ± 15, n = 7) longby 53–65 (59 ± 5, n = 7) wide in detached gravid proglottides;and 135 long by 66 wide in detached postgravid proglottides.Genital pore 22–27% of proglottis length from posteriorend. Genital atrium shallow. Vagina anterior to the cirrus sac.Ovary inverted ‘A’ shape or theta-shaped (Figs 8A, 9A,C), atposterior third of proglottis 76–213 (129 ± 56, n = 5) wide atthe isthmus region, aporal arm 166–204 (193 ± 15, n = 5)long, poral arm 152–195 (175 ± 16, n = 5) long in matureattached proglottides; 74–220 (142 ± 41, n = 28) wide, aporalarm 147–730 (379 ± 143, n = 29) long, poral arm 134–621



Fig. 8 A–C. Potamotrygonocestus fitzgeraldae n. sp. —A. Scolex. —B. Detached mature proglottis. —C. Bothridial hooks. Scale bars:A, B = 100 µm; C = 10 µm.



Fig. 9 A–D. Potamotrygonocestus fitzgeraldae n. sp. —A. Mature proglottis. —B–D. Ovary region. Scale bars = 100 µm.



(318 ± 126, n = 29) long in mature detached proglottides;141–267 (206 ± 38, n = 8) wide, aporal arm 259–565(448 ± 100, n = 8) long, poral arm 247–516 (399 ± 89, n = 8)long in detached gravid proglottides, ovarian lobes may ormay not be fused (Fig. 9A–C). Uterus indistinct in matureproglottides. Vitellaria compact 5–44 (19 ± 9, n = 179) widein two lateral longitudinal rows overlapping the cirrussac. Additional meristic and morphometric attributes ofP. fitzgeraldae are given in Table 3.

Remarks. Potamotrygonocestus fitzgeraldae resembles P. travassosiand P. chaoi in having asymmetrical hooks with prongsemerging from the posterior end of the bases, hooks approx-imately one third of the total bothridial length from theanterior end, and a cirrus sac at the level of, or anterior to,the ovarian isthmus. In possessing these characteristics,P. fitzgeraldae differs from P. amazonensis and P. magdalenensis inwhich the hooks are symmetrical with prongs emerging fromthe middle of the handle, the hooks are at the anterior 10thof the bothridia, and the cirrus sac is posterior to the ovarianisthmus.

Potamotrygonocestus fitzgeraldae most closely resemblesP. travassosi in the dimensions of the hooks, testes diameter,and ovary dimensions (see Table 3). However, P. fitzgeraldaediffers from P. travassosi in possessing more testes (an averageof 31–41 vs. 21–24, Table 3), and in having a genital pore atthe level of the anterior end of the poral ovarian lobe (Fig. 8B)rather than at, or slightly anterior to, the ovarian isthmus(Fig. 5B,C). Potamotrygonocestus fitzgeraldae further differsfrom P. chaoi in having a shorter scolex (189–474 vs.494–534) and fewer testes (23–46 vs. 64–107).

The population of P. fitzgeraldae from the Paraná Basininhabiting Potamotrygon motoro differs morphometrically andmeristically from other populations in the Amazon Basin(Table 3). For instance, specimens from the Paraná Basinpossess longer scolexes (430–474 vs. 188–312), longer hookhandles (61–72 vs. 33–51 for medial hooks, and 56–64 vs.39–54 for lateral hooks), and more testes (an average of 41 vs.an average of 31–37 testes). However, few representatives ofthis population could be examined. We examined only twocomplete specimens and few proglottides from the LowerParaná system in addition to one specimen collected byBrooks & Amato (1992) from the mid-Paraguay drainages[HWML 34094, identified by Brooks & Amato (1992) asP. orinocoensis]. Whether the population from the Paraná–Paraguay drainages constitutes a distinct species is pendingthe collection of additional material.Potamotrygonocestus maurae n. sp.: Fig. 10A–D.



Type host. Potamotrygon orbignyi (Castelnau, 1855).


Type locality. Praia do Defunto, Rio Negro, near Barcelos,Amazonas, Brazil.

Other localities. Rio Branco, 4 h from confluence with RioNegro (host deposited UFPB 3536).

Etymology. The species is named after Maura Kumagay forher kind hospitality during our field work in Belém do Pará,Brazil.

Description. Based on one immature and four incompletespecimens, and three detached proglottides. Strobila acraspe-dote, hyperapolytic, immature specimens 3.2 mm long, com-posed of 17 proglottides. Scolex 303–325 long by 323–334wide, comprised of four sessile non-septate bothridia, eachwith an apical sucker, and a pair of simple hooks at the ante-rior 10th of the bothridia. Apical sucker 55 in diameter.Scolex, neck, strobila bearing microtriches decreasing indensity posteriorly (Fig. 10A). Bothridia 280–317 (299 ± 14,n = 7) long, 149–174 (164 ± 10, n = 7) wide. Hooks 47 long,prongs 63 long, bases 26 long. Hook prongs emerging fromthe middle of the handle, hollow with a channel opening tothe outside via a single pore anteriorly adjacent to the base(Fig. 10B). Immature proglottides initially wider than long,becoming longer than wide. Detached mature proglottides1026–1127 (1067 ± 53, n = 3) long, 365–513 (421 ± 80, n = 3)wide (Fig. 10C). Testes in anterior two thirds of proglottis,66–85 (76 ± 8, n = 5) long by 57–74 (65 ± 8, n = 5) wide,22–31 (27 ± 4, n = 8) in number; 11–15 (13 ± 2, n = 5)porally, and 11–17 (14 ± 2, n = 5) aporally. Vas deferensascending from the cirrus sac to approximately the level ofthe anterior third of proglottis, recurved posteriorly to theregion of posterior-most testes; recurved region glandular(Fig. 10C). Cirrus sac in posterior third of proglottis, 105–115(111 ± 5, n = 3) long by 46–57 (52 ± 5, n = 3) wide indetached mature proglottides, containing spined eversiblecirrus (Fig. 10D). Genital pore 31–34% of proglottis lengthfrom posterior end. Genital atrium shallow. Vagina anteriorto the cirrus sac. Ovary in posterior third of proglottis173–246 (± , n =) wide. Aporal arm of ovary 324–437(376 ± 57, n = 3) long, poral arm 304–371 (343 ± 34, n = 3)long in detached mature proglottides. Uterus indistinct inmature proglottides. Vitellaria compact 26–38 (30 ± 5, n = 5)wide, in two lateral longitudinal rows extending to theposterior level of the ovary. Gravid proglottides not observed.

Remarks. Potamotrygonocestus maurae resembles P. amazonensisand P. magdalenensis in having symmetrical bothridial hooks



Fig. 10 A–D. Potamotrygonocestus maurae n. sp. —A. Scolex. —B. Bothridial hooks. —C. Mature detached proglottis. —D. Cirrus sac region.Scale bars: A, C, D = 100 µm; B = 10 µm.



at the anterior 10th of the bothridia, hook prongs emergingfrom the middle of the prong and having approximately 20testes. Conversely, the new species differs from P. travassosi,P. chaoi, and P. fitzgeraldae in which the bothridial hooks areasymmetrical, at the anterior third to quarter of the bothridiaand prongs emerge from the posterior end of the handle.Potamotrygonocestus maurae further differs from P. amazonensisand P. magdalenensis in having a genital pore at the level of theanterior end of the poral ovarian lobes rather than at the levelof, or posterior to, the ovarian isthmus. The diagnostic characterfor this species is the extension of vitellaria to the posteriorend of ovarian lobes. In other species of Potamotrygonocestus,the vitellaria reach the level of the ovarian isthmus at the most.Potamotrygonocestus sp. 7: Fig. 11A.

Host. Potamotrygon henlei (Castelnau, 1855).

Locality. Rio Tocantins, Marabá, Pará, Brazil.

Vouchers. MZUSP 5858.

Description. Based on three detached proglottides. Detachedgravid proglottides 4558 long by 802 wide; detached post-gravid proglottides 4968 long by 611 wide (Fig. 11A). Testesin two longitudinal rows in anterior two thirds of proglottis,132–161 (148 ± 13, n = 5) long by 97–146 (125 ± 21, n = 5)wide, 46–55 (51 ± 5, n = 3) in number; 26–27 (26 ± 1, n = 3)porally, and 20–28 (25 ± 4, n = 3) aporally. Vas deferensascending from the cirrus sac to the level of the anterior halfof proglottis, recurved posteriorly to the region of posterior-most testes; recurved region glandular. Cirrus sac in posteriorquarter of proglottis containing spined eversible cirrus, 219long by 109 wide in detached gravid proglottides, 270 long by113 wide in detached postgravid proglottides. Genital pore22–29% of proglottis length from posterior end. Genitalatrium shallow. Vagina anterior to the cirrus sac. Ovary inposterior quarter of proglottis 452–483 wide, aporal arm941–1257 long, poral arm 817–1066 long in detached gravidproglottides. Uterus indistinct in mature proglottides.Vitellaria compact 42–64 (54 ± 9, n = 6) wide, in two laterallongitudinal rows overlapping the cirrus sac.Potamotrygonocestus sp. 8: Fig. 11B,C.

Type host. Potamotrygon schroederi Fernándedez-Yépez, 1957.

Type locality. Catalão, confluence of Rio Negro and RioSolimões, near Manaus, Amazonas, Brazil.

Vouchers. MZUSP 5859–5864.

Description. Based on eight detached proglottides. Detachedmature proglottides 2369 long by 713 wide, and detached

postgravid proglottides 1876–3580 (2875 ± 537, n = 7) longby 657–843 (738 ± 59, n = 7) wide (Fig. 11B). Testes in twolongitudinal rows in the anterior two thirds of proglottis,76–172 (127 ± 23, n = 40) long by 77–151 (110 ± 18, n = 40)wide, 23–32 (28 ± 3, n = 8) in number. Vas deferens ascendingfrom the cirrus sac to the level of the anterior two thirds ofproglottis, recurving posteriorly to the region of posterior-most testes; recurved region glandular. Cirrus sac in posterior10th of proglottis, 192 long by 102 wide in detached matureproglottides, containing spined eversible cirrus (Fig. 11B,C).Genital pore 9–11% of proglottis length from posterior end.Genital atrium not observed. Vagina anterior to the cirrussac. Ovary in posterior third of proglottis 220 wide, aporalarm 531 long, poral arm 326 long in detached matureproglottides; and 252–367 (321 ± 44, n = 5) wide. Aporal armof ovary 601–976 (641 ± 28, n = 5) long, poral arm 309–517(417 ± 94, n = 5) long; poral arm displaced towards the mid-line by the cirrus sac. Uterus indistinct in mature proglottides.Vitellaria compact in two lateral longitudinal rows 27–80(51 ± 12, n = 55) wide not reaching the cirrus sac region.

Remarks. These specimens may represent two undescribedspecies of Potamotrygonocestus. In order to be recognized asdistinct species, further collections of additional specimensmust be made. Proglottides of Potamotrygonocestus sp. 7resemble those of P. travassosi, P. chaoi, and P. fitzgeraldaewith an inverted ‘A’ ovarian shape and a genital pore at thelevel of, or anterior to, the ovarian isthmus. However, thenumber of testes (46–55) is greater than expected for P. tra-vassosi (20–30) and in between the numbers recorded forP. fitzgeraldae (23–46) and P. chaoi (64–107). Because only threedetached proglottides of Potamotrygonocestus in Potamotrygonhenlei from Rio Tocantins were collected, it is difficult toascertain the taxonomic status of these specimens withoutfurther data.

The proglottides assigned to Potamotrygonocestus sp. 8resemble those of P. amazonensis, P. magdalenensis and P.maurae in having a relatively low number of testes (20) anda genital pore at the level of, or posterior to, the ovarianisthmus. However, Potamotrygonocestus sp. 8 differs fromthese species in having asymmetrical ovarian lobes (Fig. 11B).In addition, Potamotrygonocestus sp. 8 differs from P. magdalenensisby having the genital pore at the level of the ovarian isthmusrather than at the posterior end of the proglottis. It also dif-fers from P. maurae by having vitellaria extending only to thelevel of the ovarian isthmus rather than to the level of theposterior end of the ovarian lobes.

Key for species of Potamotrygonocestus1a Bothridial hooks asymmetrical at the anterior third toquarter, hook prongs emerging from the posterior end of thehandle: 4.



Fig. 11 A–C. —A. Potamotrygonocestus sp. 7 detached gravid proglottis. —B, C. Potamotrygonocestus sp. 8 detached mature proglottis and cirrussac region, respectively. Scales bars: A = 1 mm; B, C = 100 µm.



1b Bothridial hooks symmetrical at the anterior 10th, hookprongs emerging from the middle of the handle: 2.2a Genital pore at the level of, or posterior to, the level of theovarian isthmus; vitellaria not extending posteriorly to theovarian isthmus: 3.2b Genital pore at the level of the anterior end of the poralovarian lobe; vitellaria extending to the level of the posteriorend of the ovarian lobes: P. maurae.3a Bothridia 380–423 µm long, lateral bothridial hooks71–77 µm long, medial hooks 75–91 µm long, shallowgenital atrium present: P. amazonensis.3b Bothridia 205–330 µm long, lateral bothridial hooks26–51 µm long, medial hooks 43–78 µm long, genital atriumabsent: P. magdalenensis.4a Fewer than 50 testes per proglottides: 5.4b More than 50 testes per proglottides: P. chaoi.5a Genital pore at the level of, or slightly above, the ovarianisthmus, 21–24 testes on average: P. travassosi.5b Genital pore at the level of the anterior end of the poralovarian lobe, 31–41 testes on average: P. fitzgeraldae.

Outgroup comparison and phylogenetic analysisOutgroup choiceSpecies of Potamotrygonocestus have scoleces with a relativelysimple structure compared with other onchobothriid tetra-phyllideans. They possess simple hooks and non-septatebothridia. Of the genera currently recognized as comprisingthe Onchobothriidae Braun, 1900, only Spiniloculus South-well, 1925, Yorkeria Southwell, 1930, and Pachybothrium Baer& Euzet, 1962 share these characteristics. BalanobothriumHornel, 1911 and Pedibothrium Linton, 1909 also exhibitnon-septate bothridia but have bifid hooks. Spiniloculus andYorkeria appear to be closely related and divergent from therest of the onchobothriids by having forked scoleces andhooks without bases or internal channels. Balanobothrium,Pachybothrium, Pedibothrium, and Potamotrygonocestus all havehook prongs possessing separate channels with separate pores(Fig. 12A,B). Caira & Pritchard (1986) suggested that thischaracter could not be considered a synapomorphy for Pedi-bothrium because of its presence in Pachybothrium. However,we consider this character to be a putative synapomorphyfor Balanobothrium, Pachybothrium, Pedibothrium, andPotamotrygonocestus. Pachybothrium, Pedibothrium, and Pota-motrygonocestus lack postvaginal testes on the poral side,which we consider to be a synapomorphy for these threegenera. Thus, Pachybothrium and Pedibothrium served as out-groups for the phylogenetic analysis of Potamotrygonocestusbased on the putative synapomorphies listed above, supportingthe original outgroup choice of Brooks et al. (1981). Themonophyly of Potamotrygonocestus was based on the followingputative synapomorphies: the presence of simple hooks inwhich the length of the hook prongs are about twice the

length of the base rather than simple or bifid hooks withsame size prongs as the base, the presence of glandular cellssurrounding the vas deferens, genital pore posterior to theanterior margins of the ovarian arms rather than distinctlypreovarian, and testes restricted to the preovarian space.

Character argumentationThe characters used in the analysis are summarized in thedata matrix shown in Table 4 with the following polarizationdecisions:1 Attachment of the base of the hook prong. InPotamotrygonocestus amazonensis, P. magdalenensis, and P. mauraethe hook prong emerges from the middle of the handle.In the remaining species the prong emerges from the post-erior end of the handle. The polarity for this characteraccording to Pedibothrium would depend on a particular statementof homology between the single prong of Potamotrygonocestusand either the inner or outer hook prong of Pedibothrium. InPedibothrium, the outer prong emerges from the middle ofthe base whereas the inner prong emerges from the posteriorend (Fig. 12A). In Pachybothrium the hook prong emergesfrom the middle of the base (Fig. 12B). Thus, the polarity ofthe character is equivocal (outgroup state = ?). Characterstates: 0 = prong emerging from the posterior end of thehandle; 1 = prong emerging from the middle of the handle.2 Hook position in relation to bothridium. The bothridialhooks in P. amazonensis, P. magdalenensis, and P. maurae are

Fig. 12 A, B. —A. Typical hook morphology of Pedibothrium. —B.Typical hook morphology of Pachybothrium. Scales omitted.



attached approximately 10% of the bothridial length fromthe anterior end of the bothridia, while in the remainingspecies the hooks are attached approximately 30% of thebothridial length from the anterior end. Pedibothrium ispolymorphic for this character. Pedibothrium globicephalumLinton, 1909 and P. lintoni Caira & Pritchard, 1986 havebothridial hooks at the anterior 25–30% of the bothridia,whereas P. maccallumi Caira & Pritchard, 1986 and P.brevispine Linton, 1909 have hooks close to the anterior endof the bothridia, similar to all other onchobothriids. InPachybothrium, the hooks are at the anterior end of thebothridia in the centre of a muscular pad. It is difficult topostulate any robust statement of homology for thischaracter. Thus, we consider the polarity equivocal for thischaracter state. Character states: 0 = hooks attachedapproximately 30% of the bothridial length from the anteriorend; 1 = hooks attached approximately 10% of the bothridiallength from the anterior end.3 Hook symmetry. The medial and lateral hooks inPotamotrygonocestus may be either symmetrical (as in P.amazonensis, P. magdalenensis, and P. maurae) or asymmetrical(as in P. chaoi, P. fitzgeraldae, and P. travassosi). In Pedibothriumand Pachybothrium the bothridial hooks are symmetrical,suggesting that asymmetrical hooks are derived withinPotamotrygonocestus. Character states: 0 = hooks asymmetrical;1 = hooks symmetrical.4 Genital pore position. Potamotrygonocestus chaoi andP. maurae possess genital pores anterior to the ovarianisthmus at the level of the anterior end of the ovarian lobes.Potamotrygonocestus fitzgeraldae and P. travassosi have genitalpores at the level of the ovarian isthmus or slightly anteriorto it, whereas in the remaining species the genital pore isposterior to the isthmus. Both outgroup genera havepreovarian genital pores. Thus, we consider genital poresanterior to the ovarian isthmus at the level of the anterior endof the ovarian lobes plesiomorphic within Potamotrygonocestus.Character states: 0 = genital pores anterior to the ovarian

isthmus at the level of the anterior end of the ovarian lobes;1 = genital pores at the level of the ovarian isthmus or slightlyanterior to it; 2 = genital pores posterior to the isthmus.5 Testes number. In Potamotrygonocestus, P. chaoi has agreater number of testes (64–107) than other species ofthe genus, all of which have fewer than 60 testes. Thenumber of testes in the outgroup ranges from as few as 80in Pachybothrium hutsoni to as many as 291 in Pedibothriumglobicephalum, suggesting that fewer testes is derived withinPotamotrygonocestus. Character states: 0 = more than 60 testesper proglottid; 1 = fewer than 60 testes per proglottid.6 Vitellaria distribution. Potamotrygonocestus maurae possessvitellaria extending to the posterior margin of the proglottid,whereas in the remaining species of Potamotrygonocestus thevitellaria only extend to the level of the ovarian isthmus. Bothoutgroup genera have vitellaria which extend to the poster-ior margin of the proglottid. This condition is consideredplesiomorphic within Potamotrygonocestus. Character states:0 = posterior end of the vitellaria extends to the posteriormargin of the proglottid; 1 = posterior end of the vitellaria atthe level of the ovarian isthmus.

Phylogenetic analysisThe phylogenetic analysis of six morphological characters forsix species of Potamotrygonocestus generated a single tree eightsteps long, with a consistency index of 0.87, a retention indexof 0.90, and a rescaled consistency index of 0.79 (Fig. 13).

DiscussionTaxonomic accountThe taxonomy of Potamotrygonocestus has suffered frominadequate sample sizes for respective species from whichdescriptions could take into account intra- and interpopula-tional variation. The majority of the species descriptions havebeen based on a small number of specimens from a singlelocality, usually from a single host species. In the presentstudy, spiral valves were fixed in the field and then analysedin the laboratory, providing more specimens than previouslyavailable for study, although some populations were stillpoorly represented.

Among the six species recognized in this study, two pheneticgroupings can be distinguished. One grouping is representedby the clade comprising Potamotrygonocestus chaoi, P. fitzgeraldae,and P. travassosi, which can be recognized by possessingasymmetrical hooks at the anterior third to quarter of thebothridia, and prongs emerging from the posterior end ofthe handle (hereafter referred to as the P. travassosi group).The other grouping comprises the paraphyletic speciesP. amazonensis, P. magdalenensis and P. maurae, which havesymmetrical hooks at the anterior 10th of the bothridia andprongs emerging from the middle of the handle (hereafterreferred to as the P. magdalenensis group).

Table 4 Data matrix for six species of Potamotrygonocestus and six morphological characters.

Taxa

Characters

1 2 3 4 5 6

Outgroup coding ? ? 0 0 0 0P. amazonensis 1 1 0 2 1 1P. magdalenensis 1 1 0 2 1 1P. maurae 1 1 0 0 1 0P. fitzgeraldae 0 0 1 1 1 1P. travassosi 0 0 1 1 1 1P. chaoi 0 0 1 0 0 1



Within the P. travassosi group, P. fitzgeraldae might rep-resent a species complex. As discussed in the remarks onP. fitzgeraldae, there are morphological differences betweenthe populations of this species from Rio Negro and RioXingú as compared with those of the Paraná drainages.However, as mentioned above, the sample size for specimensfrom the Paraná drainages undermine any further con-clusions on the taxonomic status of specimens collectedfrom that basin. For the P. magdalenensis group, P. amazonensismight also represent a species complex. Specimens attributedto P. amazonensis from the Paraná drainage inhabiting Pota-motrygon falkneri possess a cirrus sac approximately at thelevel of the ovarian isthmus (Fig. 3C), differing from themore posterior position for this structure found in specimensof the type series for P. amazonensis (Fig. 3A) and specimensfrom other localities such as Rio Negro and the Lower Amazon.In other species of Potamotrygonocestus, the position of thegenital pore seems to be fairly consistent. However, becauseof the small number of specimens collected, no decision canbe made on whether the patterns observed constituteinterpopulational variation or are indicative of the inclusionof different species within the concept of P. amazonensis.

Phylogeny of PotamotrygonocestusBrooks et al. (1981) used four characters to infer sister-grouprelationships for three species of Potamotrygonocestus [P. ama-zonensis, P. magdalenensis and P. travassosi (as P. orinocoensis)]:length of bothridial hook prongs [called ‘bothridial hooklength’ by Brooks et al. (1981)], hook prong attachment,ovarian shape, and vitellaria configuration. Of those characters,only the hook prong attachment was considered herein. The

length of bothridial hook prongs was not included in ourstudy because we found no gap among the ranges obtainedfor this parameter (see Tables 2 and 3). The ovarian shape wasdefined by Brooks et al. (1981) as having two states; inverted‘A’, considered to be plesiomorphic, and ‘theta-shaped’, con-sidered to be the derived state within Potamotrygonocestus. Ourtaxonomic account suggested that a ‘theta-shaped’ ovary maybe dependent on the developmental stage of the proglottid.Specimens with a ‘theta-shaped’ ovary were observed in P.travassosi and P. fitzgeraldae. However, these species are poly-morphic for the character. In accordance with Brooks et al.(1981), outgroup analysis suggests that the presence of a ‘theta-shaped’ ovary is derived within the ingroup. Thus, if includedin the analysis, this character would support the sister-grouprelationship between P. travassosi and P. fitzgeraldae, whichherein was supported by the presence of genital poresanterior to the ovarian isthmus [character 4(1)]. For vitellarineconfiguration, Brooks et al. (1981) considered two characterstates: vitellaria follicular and compact. As discussed in thetaxonomic account for Potamotrygonocestus, a follicular vitel-larium is only observed in late development of the proglottid.Species of this genus usually possess compact vitellaria. Thus,we did not include this character in our analysis. Brooks et al.(1981) concluded that P. magdalenensis and P. travassosi weresister species (based on the presence of compact vitellaria),with P. amazonensis their sister species. The results of our analysissuggest that P. magdalenensis is the sister species of P. amazo-nensis, and that P. travassosi is the sister species of P. fitzger-aldae, which together are the sister group of P. chaoi (Fig. 13).

The relationship between Potamotrygonocestus and otheroncobothriids is the least known of the tetraphyllideans that

Fig. 13 Phylogenetic hypothesis for sixspecies of Potamotrygonocestus based on sixmorphological characters.



inhabit freshwater potamotrygonids. Species of Pachybothriumand Pedibothrium are parasites of orectolobiformes sharks.If these genera do, in fact, share a close common ancestorwith Potamotrygonocestus, as the putative synapomorphiesdescribed above suggest [see also Caira et al. (1999)], it wouldimply that the ancestor of Potamotrygonocestus underwent ahost switch from sharks to stingrays. There are three testablehost switching scenarios: (i) the host switch occurred prior tothe invasion of the ancestor of the potamotrygonids intoSouth American river systems; (ii) the host switch occurredas a result of the invasion of sharks and the ancestor ofpotamotrygonids into South American river systems; and(iii) the host switch occurred after the invasion when thepotamotrygonids were already established in the rivers ofSouth America. The first hypothesis would be corroboratedby finding a species of Potamotrygonocestus, or its sister group,inhabiting the marine sister group of potamotrygonids. Thesecond hypothesis predicts that sharks hosting the ancestor ofPotamotrygonocestus coexisted with potamotrygonids duringtheir establishment in the fluvial systems of South America.The third hypothesis predicts that sharks coexisted withpotamotrygonids after their establishment in the fluvialsystems of South America. There is evidence that euryhalinebullsharks (Carcharhinus) were present in South Americaduring the Late Miocene Seaway (Räsänen et al. 1995), butnothing resembling Potamotrygonocestus has been reportedin bullsharks. Tests of these hypotheses must await furthercollections of Potamotrygonocestus as well as more extensiveinventories of eucestodes of marine elasmobranchs.

Small sample sizes and limited collections also limitgeneralization concerning distributional patterns and hostspecificity within Potamotrygonocestus. However, some patternsthat deserve comment have emerged in our study. Potamotry-gonocestus amazonensis, P. fitzgeraldae, and P. travassosi arewidely distributed geographically and inhabit more than onespecies of freshwater potamotrygonid, a pattern that has beenreported for other helminths inhabiting potamotrygonids(Brooks & Amato 1992; Brooks 1995; Marques 2000). Incontrast, P. magdalenensis, P. maurae, and P. chaoi are onlyknown to inhabit a single species of host (Potamotrygonmagdalenensis, P. schroederi, and Plesiotrygon iwamae, respec-tively) from single localities (Rio Magdalena and LowerSolimões, respectively).

Potamotrygonocestus magdalenensis inhabits Potamotrygonmagdalenae, endemic to the Rio Magdalena, a river systemthat was isolated from other neotropical hydrographic basinsby the uplift of the Andes, which may account for itsrestricted host and geographical range. Potamotrygonocestusmaurae and P. chaoi, on the other hand, inhabit hosts thatcoexist with other species of freshwater potamotrygonids, butwere collected in only a single host species. If their restrictedgeographical distribution and host range is not a sampling

artefact, then we must look beyond allopatry to trophicsegregation among co-occurring and closely related hosts, orto some intrinsic aspect of the biology of the eucestodespecies themselves, for an explanation.

AcknowledgementsWe are indebted to Lisa Nodwell, Jaime Carvalho Junior,Labbish Chao and the staff and students of the Projeto Piaba,Barcelos, Amazonas, Brazil, for their assistance during thefield work in the Amazon region. We are grateful for the hos-pitality of Maura Kumagay and her family to FPLM duringhis stay in Belém do Pará. We gratefully acknowledgeSeñores Lauriano Sanchez, Juan Sanchez, Hector Sanches,and Andres Gonzales for their help in Puerto Reconquista,Santa Fé, Argentina. This work could not be realized withoutthe help of local fishermen from Argentina and the Amazonregion to whom we express our gratitude. We thank ScottMonks and Anindo Choudhury for reviewing early versionsof this manuscript. We are also thankful to Gerhard Pohlefor allowing us to use his image analysis software. This workwas financially supported by CNPq (Consenho Nacionalde Desenvolvimento Científico e Tecnológico, FederalGovernment of Brazil) doctorate fellowship to FPLM andNSERC (Natural Sciences and Engineering Council ofCanada) operating grant A7696 to DRB.

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lackwell Publishing, LtdSystematics and phylogeny of ... · Pedibothrium maccallumi Caira & Pritchard, 1986 USNPC 36011 (holotype). Pedibothrium brevispine Linton, 1909 USNPC 9001