Larval stages of Romaleon gibbosulum and Metacarcinus magister (Crustacea: Decapoda: Cancridae) described from laboratory reared materials

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Larval stages of Romaleon gibbosulum and Metacarcinusmagister (Crustacea: Decapoda: Cancridae) described fromlaboratory reared materialsAuthor(s): Seok Hyun Lee and Hyun Sook KoSource: Proceedings of the Biological Society of Washington, 127(1):157-174.2014.Published By: Biological Society of WashingtonDOI: http://dx.doi.org/10.2988/0006-324X-127.1.157URL: http://www.bioone.org/doi/full/10.2988/0006-324X-127.1.157

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http://dx.doi.org/10.2988/0006-324X-127.1.157

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Larval stages of Romaleon gibbosulum and Metacarcinus magister(Crustacea: Decapoda: Cancridae) described from laboratory

reared materials

Seok Hyun Lee and Hyun Sook Ko*

(SHL, HSK) Department of Biological Science, Silla University, Busan 617-736,Republic of Korea, e-mail: [email protected], [email protected]

Abstract.—The complete larval development of Romaleon gibbosulum,comparing five zoeal stages and one megalopal stage, and the first zoea ofMetacarcinus magister are described and illustrated. The zoeal morphologiesof the two species are compared with those known for other Cancridaespecies. Based on the zoeal mouthparts, R. gibbosulum shows more affinity tospecies of Glebocarcinus than its congeners. Metacarcinus magister is differentfrom its congeners and coincides well with Cancer productus. These resultsmay indicate that a re-examination of their generic classification is necessary.

Keywords: Cancridae, description and illustration, larval morphology,Metacarcinus magister, Romaleon gibbosulum

Crabs of the Cancridae comprise 31species and 6 genera (Ng et al. 2008,Schram & Ng 2012), of which larvaldescriptions are known for 15 species and4 genera (Table 1).

Romaleon gibbosulum inhabits sandyand muddy bottoms at depths between30–100 m with a reported distributionranging from Japan to North China andKorea (Sakai 1976). Although Terada(1987) described the first and second zoealstages of this species, its complete larvaldevelopment is still unknown. The Dunge-ness crab, Metacarcinus magister, inhabitssandy bottoms from low tidal to 230 m indepth, with a reported distribution fromthe Aleutians to California along thePacific coast of America (Wicksten 2011).Although, the first zoeal stage and acomplete larval stage were described byMir (1961) and Poole (1966), respectively,their descriptions are considered to beincomplete by modern-day larval stan-dards. Therefore, the aims of this paperare to describe the complete larval devel-

opment of R. gibbosulum and the first zoealstage of M. magister, to compare themwith previously described zoeas, and toexamine their systematic positions withinthe family Cancridae.

Materials and Methods

On 12 Feb 2010 an ovigerous crab ofRomaleon gibbosulum was collected using afishing trap at a depth of 30 m from Gijang(35819 0N, 129819 0E), Busan, Korea. Atotal of 108 zoeas for R. gibbosulum werereared individually at a water temperatureof 18 6 18C. Each zoea was held in aplastic well containing seawater. The waterwas changed daily and each zoea wasprovided with newly hatched Artemianauplii once a day. Each culture waschecked daily for exuviae and dead larvae.Molts and dead larvae were fixed andpreserved in 95% ethanol for later exam-ination. On 11 Mar 2010 the zoeas hatchedin the laboratory. An ovigerous crab ofMetacarcinus magister was collected by* Corresponding author.

PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON127(1):157–174. 2014.

trawl at a depth of 37 m in Ship Harbor(488280N, 1228400W), Anacortes, Washing-ton, U.S.A., on 27 Jan 2004. The zoeashatched in the laboratory on 11 Feb 2004.

Dissected appendages were examinedand drawn using a Leitz Laborlux Smicroscope with a camera lucida. Setalcounts on appendages and measurementswere based on the mean of ten specimensfor each zoeal stage. The sequence of thelarval description (Clark et al. 1998) isbased on the malacostracan somite planand described from anterior to posterior.Setal armature is described from proximalto distal segments and in order of endopodto exopod. The long plumose natatorysetae of the first and second maxillipedsand aesthetascs of the antennule in thefifth zoeal stage are drawn truncated. Amicrometer was used for measurements:CL (carapace length) was taken from theanterior margin of the eye to the mostposterior carapace margin for zoeas and

megalopa; CW (carapace width) wasmeasured across the widest part of thecarapace for megalopa; and RDL (rostralspine to dorsal spine length) was takenfrom the tip of the rostral spine to the tipof the dorsal spine for zoea. The cancridclassification follows that of Schram & Ng(2012). The larvae and spent females aredeposited at Silla University, Busan,Korea.

ResultsRomaleon gibbosulum (De Haan, 1833)

Figs. 1–7

The complete larval development con-sists of five zoeal stages and one megalopalstage. The minimum duration of zoealstages I to V at 208C is 8, 6, 6, 6, and 8days, respectively. Megalopae did notmetamorphose to young crabs. The firstzoeal stage is described and illustrated

Table 1.—List of larval stages of cancrid species and sources of descriptions. Abbreviations: Mega ¼megalopal stage, Pre ¼ prezoeal stage, ZI–ZV ¼ zoeal stages I to V, respectively.

Species Larval stages Source

CancerC. porteri Rathbun, 1930 ZI–ZV, Mega Fagetti 1960C. productus Randall, 1840 ZI–ZV, Mega Trask 1970C. plebejus Poeppig, 1836 (¼ ? C. coronatusMolina, 1782)

Pre, ZI Quintana & Saelzer 1986

(¼ C. irroratus Say, 1817) ZI–ZV, Mega Sastry 1977bC. pagurus Linnaeus, 1758 ZI–ZV, Mega Ingle 1981C. borealis Stimpson, 1859 ZI–ZV, Mega Sastry 1977a

GlebocarcinusG. oregonensis (Dana, 1852) ZI–ZV, Mega Kim 2002G. amphioetus (Rathbun, 1898) ZI–ZV, Mega Iwata & Konishi 1981, Kornienko &

Korn 2010Metacarcinus

M. anthonyi (Rathbun, 1897) ZI–ZV, Mega Anderson 1978M. gracilis (Dana, 1852) ZI–ZV, Mega Ally 1975M. novaezelandiae (Hombron & Jacquinot,1846)

ZI Wear & Fielder 1985

M. edwardsii (Bell, 1835) ZI–ZV, Mega Quintana 1983M. magister (Dana, 1852) ZI–ZV, Mega Poole 1966

RomaleonR. antennarium (Stimpson, 1856) ZI–ZV, Mega Roesijadi 1976R. gibbosulum (De Haan, 1833) ZI, ZII Terada 1987R. polyodon (Poeppig, 1836) (¼ ? Cancersetosus Molina, 1782)

ZI–ZV, Mega Quintana & Saelzer 1986

158 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON

completely. For the second zoeal stage,only the main differences from the firstzoea are described.

First zoea (Figs. 1A, 2).—Size: CL 0.436 0.01 mm; RDL 1.18 6 0.01 mm.

Chromatophores (Fig. 1A): Predomi-nantly black pigments occurring behindand between eyes, on basis of antenna,mouthparts, dorsal and lateral carapacespines, on lateral expansion of carapace,and on posterior margins of pleomeres 1–5. Red chromatophores on basis of lateralcarapace spine, on lateral expansion ofcarapace, and on telson.

Carapace (Fig. 2A): Rostral spinestraight, shorter than dorsal spine; dorsalspine with several minute tubercles, long,curved distally; lateral spine approximatelyhalf length of rostral spine; pair of postero-dorsal setae present; each ventral marginserrated and devoid of setae; eyes sessile.

Antennule (Fig. 2B): Uniramous; endo-pod absent; exopod with 1 long, stoutaesthetasc, 2 shorter, thinner aesthetascs, 1short seta, all terminal.

Antenna (Fig. 2C): Biramous; protopodslightly shorter than rostral spine; rostralspine with 2 rows of spinules; endopod budabsent; exopod with 2 (1 long, 1 shorter)terminal setae, approximately one-third ofprotopod length.

Mandibles (Fig. 2D): Asymmetrical;right molar process with 2 teeth, confluentwith incisor process; palp absent.

Maxillule (Fig. 2E): Coxal endite with 7setae; basial endite with 5 setae; endopod2-segmented: proximal segment with 1seta, distal segment with 6 (2 subterminal,4 terminal) setae; exopodal and epipodalsetae absent.

Maxilla (Fig. 2F): Coxal endite bilobed,with 3þ4 setae; basial endite bilobed, with5þ4 setae; endopod bilobed with 3þ3 setae;exopod (scaphognathite) margin with 4plumose setae and 1 long distal plumosestout process.

First maxilliped (Fig. 2G): Coxa with-out seta; basis with 9 setae arranged2þ2þ3þ2; endopod 5-segmented with 2, 2,1, 2, 5 (1 subterminal, 4 terminal) setae;exopod 2-segmented, distal segment with 4long terminal plumose natatory setae.

Second maxilliped (Fig. 2H): Coxawithout seta; basis with 4 setae arranged1þ1þ1þ1; endopod 3-segmented, with 1, 1,5 (2 subterminal, 3 terminal) setae; exopod2-segmented, distal segment with 4 longterminal plumose natatory setae.

Third maxilliped: Absent.Pereiopods: Absent.Pleon (Fig. 2A, I): With 5 pleomeres;

pleomere 2 with pair of lateral processesdirected anteriorly; pleomeres 2–5 each

Fig. 1. Romaleon gibbosulum, live specimens. A, first stage zoeas; B, megalopa.

VOLUME 127, NUMBER 1 159

Fig. 2. Romaleon gibbosulum, first zoeal stage. A, lateral view; B, antennule; C, antenna; D, mandibles; E,maxillule; F, maxilla; G, first maxilliped; H, second maxilliped; I, dorsal view of pleon and telson; J,outermost seta of telson. Scale bars: A, I ¼ 0.5 mm; B–H, J ¼ 0.1 mm.


with pair of posterodorsal setae, pleomeres3–5 with prominent posterolateral process-es; pleopod absent.

Telson (Fig. 2A, I, J): Each fork long,with 1 lateral stout spine, 1 small lateralspine, and 1 large dorsomedial spine;posterior margin with 3 pairs of setae,outermost pair of setae strongly denticu-late on inner margin.

Second zoea (Fig. 3).—Size: CL 0.44 6

0.01 mm; RDL 1.43 6 0.01 mm.Carapace (Fig. 3A): Dorsal spine with 4

pairs of setae; 2 pairs of anterodorsal setaepresent, each ventral margin with 1 poste-rior seta; eyes stalked.

Antennule (Fig. 3B): Exopod with 6aesthetascs (2 subterminal, 4 terminal) anda seta.

Antenna (Fig. 3C): Exopod approxi-mately one-quarter length of protopod.

Mandibles (Fig. 3D): Right molar pro-cess with 4 teeth, confluent with incisorprocess.

Maxillule (Fig. 3E): Basial endite with 7setae; exopodal plumose seta present.

Maxilla (Fig. 3F): Exopod (scapho-gnathite) margin with 11 marginal plu-mose setae of equal size.

First maxilliped (Fig. 3G): Exopoddistal segment with 6 long terminal nata-tory setae.

Second maxilliped (Fig. 3H): Exopoddistal segment with 6 long terminal nata-tory setae.

Pleon (Fig. 3I): Posterolateral processesof pleomeres 3–5 more prominent.

Third zoea (Fig. 4).—Size: CL 0.58 6

0.03 mm; RDL 1.77 6 0.02 mm.Carapace (Fig. 4A): Three pairs of

anterodorsal setae present, each ventralmargin with 3 posterior setae.

Antennule (Fig. 4B): Exopod with 4aesthetascs and 1 seta.

Antenna (Fig. 4C): Endopod bud pres-ent.

Mandibles (Fig. 4D): Left and rightmolar processes with 1 and 5 teeth,confluent with incisor processes.

Maxillule (Fig. 4E): Basial endite with 8setae.

Maxilla (Fig. 4F): Basial endite with 5þ5setae; exopod (scaphognathite) marginwith 19 marginal plumose setae.

First maxilliped (Fig. 4G): Coxa with 1seta; exopod distal segment with 8 longterminal natatory setae.

Second maxilliped (Fig. 4H): Exopoddistal segment with 8 long terminal nata-tory setae.

Pleon (Fig. 4I): With 6 pleomeres;pleomere 1 with 1 dorsomedial seta.

Telson (Fig. 4I): Small lateral spineabsent; posterior margin with 4 pairs ofsetae.

Fourth zoea (Fig. 5).—Size: CL 0.82 6


pairs of setae; each ventral margin with 4posterolateral setae.

Antennule (Fig. 5B): Exopod with 6 (2subterminal, 4 terminal) aesthetascs andterminal simple seta.

Antenna (Fig. 5C): Endopod bud moredeveloped, slightly shorter than exopod.

Mandibles (Fig. 5D): Left molar processwith 2 teeth, confluent with incisor pro-cess.

Maxillule (Fig. 5E): Coxal and basialendites each with 8 and 11 setae, respec-tively.

Maxilla (Fig. 5F): Basial endite with 6þ5setae; exopod (scaphognathite) marginwith 28 marginal plumose setae.

First maxilliped (Fig. 5G): Exopoddistal segment with 10 long terminalnatatory setae.

Second maxilliped (Fig. 5H): Exopoddistal segment with 10 long terminalnatatory setae.

Third maxilliped (Fig. 5I): Biramousbud.

Pereiopods (Fig. 4A): Present as buds.Pleon (Fig. 5J): Pleomeres 2–6 with

pleopod buds without endopods.Telson (Fig. 5J): Posterior margin with 5

pairs of setae.


Fig. 3. Romaleon gibbosulum, second zoeal stage. A, lateral view; B, antennule; C, antenna; D, mandibles;E, maxillule; F, maxilla; G, first maxilliped; H, second maxilliped; I, dorsal view of pleon and telson. Scalebars: A, I ¼ 0.5 mm; B–H ¼ 0.1 mm.


Fig. 4. Romaleon gibbosulum, third zoeal stage. A, lateral view; B, antennule; C, antenna; D, mandibles;E, maxillule; F, maxilla; G, first maxilliped; H, second maxilliped; I, dorsal view of pleon and telson. Scalebars: A, I ¼ 0.5 mm; B–H ¼ 0.1 mm.


Fig. 5. Romaleon gibbosulum, fourth zoeal stage. A, lateral view; B, antennule; C, antenna; D, mandibles;E, maxillule; F, maxilla; G, first maxilliped; H, second maxilliped; I, third maxilliped; J, dorsal view of pleonand telson. Scale bars: A, J ¼ 0.5 mm; B–I ¼ 0.1 mm.


Fig. 6. Romaleon gibbosulum, fifth zoeal stage. A, lateral view; B, antennule; C, antenna; D, mandibles; E,maxillule; F, maxilla; G, first maxilliped; H, second maxilliped; I, third maxilliped; J, chela and pereiopods; K,dorsal view of pleon and telson. Scale bars: A, K ¼ 0.5 mm; B–J ¼ 0.1 mm.



Fifth zoea (Fig. 6).—Size: CL 1.10 6


pairs of setae; 4 pairs of anterodorsal setaepresent, each ventral margin with 10posterolateral setae.

Antennule (Fig. 6B): Endopod budpresent; exopod with 13 (9 subterminal, 4terminal) aesthetascs, 2 terminal setae.

Antenna (Fig. 6C): Endopod slightlyshorter than protopod.

Mandibles (Fig. 6D): Palp present.Maxillule (Fig. 6E): Coxal endite with

11 setae; basial endite with 15 setae;epipodal seta present.

Maxilla (Fig. 6F): Coxal endite with 4þ4setae; basial endite with 8þ8 setae; exopod(scaphognathite) margin with 31 marginalplumose setae.

First maxilliped (Fig. 6G): Coxa with 2setae; exopod distal segment with 12 longterminal natatory setae.

Second maxilliped (Fig. 6H): Exopoddistal segment with 12 long terminalnatatory setae.

Third maxilliped (Fig. 6I): Endopod andexopod more developed; epipod bud pres-ent.

Pereiopods (Fig. 6J): More developed,segments slightly differentiated, chelaprominent and bilobed.

Pleon (Fig. 6K): Pleomere 1 with 3dorsomedial setae; pleopod buds moredeveloped, endopods present on pleopods1–5.

Telson (Fig. 6K): Dorsomedial surfacewith 1 pair of setae.

Megalopa (Figs. 1B, 7).—Size: CL 1.646 0.08 mm; CW 1.37 6 0.04 mm.

Chromatophores (Fig. 1B): Black andyellow pigments occurring between eyes,on medial region and lateral expansions of

carapace, on basis of dorsal carapacespine, on pereiopods 1–5, and on pleo-meres 1–5. Red chromatophores on medialregion and posterolateral expansion ofcarapace, on dorsal carapace spine, andon chela.

Carapace (Figs. 1B, 7A): Subquadrate,longer than wide, with well-developedrostrum and dorsal spine directed posteri-orly; eyes well developed.

Antennule (Fig. 7B): Peduncle 3-seg-mented, segment 2 with 2 setae, segment 3with 1 seta; endopod 2-segmented, with 4(1 subterminal, 3 terminal) setae on distalsegment; exopod 4-segmented: segment 1unarmed, segment 2 with 11 aesthetascs,segment 3 with 9 aesthetascs and 1 seta,segment 4 with 6 subterminal aesthetascsand 1 terminal seta.

Antenna (Fig. 7C): Peduncle 3-segment-ed, each with 3, 2, and 4 setae, respectively;flagellum 8-segmented, each with 0, 0, 4, 0,5, 0, 4, and 4 setae, respectively.

Mandible (Fig. 7D): Endopod palp 3-segmented, distal segment with 9 marginalsetae.

Maxillule (Fig. 7E): Coxal endite with14 (8 simple, 6 cuspidate) setae; basialendite with 25 (17 simple, 8 cuspidate)setae; endopod unsegmented with 3 (1proximal, 2 terminal) setae.

Maxilla (Fig. 7F): Coxal endite bilobed,with 6þ5 setae; basial endite bilobed with9þ9 setae; endopod with 2 proximalplumose setae; exopod (scaphognathite)with 53 marginal plumose setae, 2 surfacesimple setae.

First maxilliped (Fig. 7G): Coxal enditewith 12 setae; basial endite with 21 setae;endopod unsegmented with 4 (1 proximal,3 terminal) setae; exopod 2-segmented,proximal segment with 2 terminal plumose

Fig. 7. Romaleon gibbosulum, megalopal stage. A, dorsal view; B, antennule; C, antenna; D, mandible; E,

maxillule; F, maxilla; G, first maxilliped; H, second maxilliped; I, third maxilliped; J, chela; K–N, pereiopods2–5, respectively; O, first pleopod; P, uropod; Q, dorsal view of pleon and telson. Scale bars: A, Q¼ 0.5 mm;B–P ¼ 0.1 mm.


setae, distal segment with 5 long terminalplumose setae.

Second maxilliped (Fig. 7H): Coxa andbasis not differentiated; endopod 4-seg-mented, each with 1, 1, 6, and 9 setae,respectively; exopod 2-segmented, proxi-mal segment with 1 medial seta, distalsegment with 5 long terminal plumosesetae.

Third maxilliped (Fig. 7I): Coxa andbasis not differentiated; endopod 5-seg-mented, each with 23, 10, 11, 12, and 8setae, respectively; exopod 2-segmented,proximal segment with 3 setae, distalsegment with 5 long terminal plumosesetae.

Cheliped (Fig. 7J): All segments withfew short setae; ischial spine distinct; tipsof fingers slightly hooked.

Pereiopods 2–5 (Fig. 7K–N): All seg-ments well differentiated, sparsely armedwith setae; only pereiopod 2 with distinctischial spine; dactyli of pereiopods 2–4with 6 spines on inner margins, that ofpereiopod 5 with 3 long curved (2 simple, 1denticulate) setae; tips sharply pointed.

Pleopods (Fig. 7O, P): Biramous, excepturopods. Endopod with 3 cincinuli; pleo-pods 1–4 with 16, 16, 14, and 13 longplumose natatory setae on each distalsegment, uropod with 8 long plumosenatatory setae on distal segment.

Pleon (Fig. 7Q): Pleon 6-segmented;pleomere 1 with 3 pairs of posterolateralsetae, pleomeres 2–4 each with 3 pairs ofdorsal and 3 pairs of posterolateral setae,pleomere 5 with 4 pairs of dorsal and 2pairs of posterolateral setae, pleomere 6with 3 pairs of posteromarginal setae;broad.

Telson (Fig. 7Q): Rounded with 2 pairsof dorsal setae.

Metacarcinus magister (Dana, 1852)Fig. 8

First zoea (Fig. 8).—Size: CL 0.64 6

0.01 mm; RDL 1.99 6 0.03 mm.

Carapace (Fig. 8A): Rostral spinestraight, shorter than dorsal spine; dorsalspine with several minute tubercles, long,curved distally; lateral spine approximatelyhalf length of rostral spine; pair of postero-dorsal setae present; each ventral marginsmooth, devoid of marginal setae; eyessessile.

Antennule (Fig. 8B): Uniramous; endo-pod absent; exopod with 2 long, stoutaesthetascs, 2 shorter, thinner aesthetascs,1 shorter seta, all terminal.

Antenna (Fig. 8C): Biramous; protopodshorter than rostral spine with 2 rows ofspinules; endopod bud absent; exopodwith 3 (1 long, 2 shorter) terminal setae,approximately one-third of the protopodlength.

Mandibles (Fig. 8D): Asymmetrical;right molar process with 2 teeth, confluentwith incisor process; palp absent.

Maxillule (Fig. 8E): Coxal endite with 7setae; basial endite with 5 setae; endopod2-segmented, proximal segment with 1seta, distal segment with 6 (2 subterminal,4 terminal) setae; exopodal and epipodalsetae absent.

Maxilla (Fig. 8F): Coxal endite bilobed,with 3þ4 setae; basial endite bilobed, with5þ4 setae; endopod bilobed, with 3þ4setae; exopod (scaphognathite) marginwith 4 plumose setae and 1 long distalstout process.

First maxilliped (Fig. 8G): Coxa with 1seta; basis with 10 setae arranged 2þ2þ3þ3;endopod 5-segmented with 3, 2, 1, 2, 5 (1subterminal, 4 terminal) setae; exopod 2-segmented, distal segment with 4 longterminal plumose natatory setae.

Second maxilliped (Fig. 8H): Coxawithout seta; basis with 4 setae arranged1þ1þ1þ1; endopod 3-segmented, with 1, 1,5 (2 subterminal, 3 terminal) setae; exopod2-segmented, distal segment with 4 longterminal plumose natatory setae.

Third maxilliped: Absent.Pereiopods: Absent.Pleon (Fig. 8A, I): With 5 pleomeres;

pleomere 2 with a pair of lateral processes


Fig. 8. Metacarcinus magister, first zoeal stage. A, lateral view; B, antennule; C, antenna; D, mandibles; E,maxillule; F, maxilla; G, first maxilliped; H, second maxilliped; I, dorsal view of pleon and telson; J,outermost seta of telson. Scale bars: A, I ¼ 0.5 mm; B–H, J ¼ 0.1 mm.


directed anteriorly; pleomeres 2–5 eachwith pair of posterodorsal setae, pleomeres3, 4 with prominent posterolateral pro-cesses; pleopod absent.

Telson (Fig. 8A, I, J): Each fork long,with 1 lateral stout spine, 1 small lateralspine, 1 large dorsomedial spine; posteri-or margin with 3 pairs of setae, outer-most seta strongly denticulate on innermargin.

Discussion

The complete larval development ofRomaleon gibbosulum is described for thefirst time in the present study, althoughTerada (1987) briefly described the first

two zoeal stages of this species. However,there are some differences between hisdescription and the present study (Table2). One difference, zoeal sizes, could be dueto zoeal culture or preservation techniques.The other differences may be due tooverlooking the characters of the carapace,antennule, maxilla, and telson, especially,the posterior margin of the telson; theoutermost seta is strongly denticulate onits inner margin.

A comparison of the first zoeal charac-teristics of Metacarcinus magister as de-scribed by Poole (1966) and the presentstudy is given in Table 3. A main differenceis the setation of the first maxilliped; thebasis possessing nine setae in his descrip-tion and ten setae in this study and the

Table 2.—Comparison between zoeal characteristics of Romaleon gibbosulum as described by Terada (1987)and present study. ND ¼ no description.

Characters Terada (1987) Present study

Zoea ICL 0.38 mm 0.43 mmRDL 0.88 mm 1.18 mm

CarapaceDorsal spine Smooth With minute tuberclesVentral margin ND SerratedPosterodorsal region ND With 1 pair of setae

Antennule With 3 aesthetascs With 3 aesthetascs, 1 setaMandibles ND AsymmetricalMaxilla

Coxal endite With 3þ3 setae With 3þ4 setaeTelson

Posterior margin ND Outermost seta denticulate on inner marginZoea II

CL 0.46 mm 0.44 mmRDL 1.20 mm 1.43 mm

CarapaceDorsal spine ND With 4 pairs of setaeAnterodorsal region ND With 2 pairs of setaePosterodorsal region ND With 1 pair of setaeVentral margin ND With 1 seta

Antennule With 3 aesthetascs, 2 setae With 6 aesthetascs, 1 setaMandibles ND AsymmetricalMaxilla

Coxal endite With 4þ4 setae With 3þ4 setaeTelson

Posterior margin ND Outermost seta denticulate on inner marginFork With 2 (1 lateral,

1 dorsomedial) spinesWith 3 (1 lateral stout, 1 small lateral,

1 dorsomedial) spines


outermost seta in the posterior margin ofthe telson being strongly denticulate on theinner margin. This character was alsodescribed for two additional North Pacific

cancrid species [Glebocarcinus amphioetusby Kornienko & Korn (2010), G. orego-nensis by Kim (2002)], three Atlanticcancrid species [Cancer borealis by Sastry

Table 3.—Comparison between first zoeal characteristics of Metacarcinus magister as described by Poole(1966) and present study. ND ¼ no description.

Characters Poole (1966) Present study

CL ND 0.64 mmRDL ND 1.99 mmCarapaceDorsal spine ND With minute tuberclesPosterodorsal region ND With 1 pair of setae

Antennule With 2 aesthetascs, 1 seta With 4 aesthetascs, 1 setaMaxilluleCoxal endite With 6 setae With 7 setae

Maxilliped 1Coxa ND With 1 setaBasis With 9 (2þ2þ2þ3) setae With 10 (2þ2þ3þ3) setae

TelsonPosterior margin ND Outermost seta denticulate on inner marginFork With 2 (1 lateral stout,

1 dorsomedial) spinesWith 3 (1 lateral stout, 1 small lateral,1 large dorsomedial) spines

Table 4.—Comparison of zoeal characteristics in 15 species of Cancridae. ZIII ¼ third zoeal stage.

Maxillule Maxilla Maxilliped 1

Endopod Endopod Basis Endopod

Species Setae Setae Setae Setae Source

CancerC. porteri 1, 1þ4 3þ4 9 3, 2, 1, 2, 5 Fagetti 1960C. productus 1, 2þ4 3þ4 10 3, 2, 1, 2, 5 Trask 1970C. plebejus

(¼ ? C. coronatus)1, 2þ4 3þ5 10 3, 2, 1, 2, 5 Quintana & Saelzer 1986

(¼ C. irroratus) Sastry 1977bC. pagurus 1, 2þ4 3þ5 10 3, 2, 1, 2, 5 Ingle 1981C. borealis 1, 2þ4 3þ5 10 3, 2, 1, 2, 5 Sastry 1977a

GlebocarcinusG. oregonensis 1, 2þ4 3þ3 9 2, 2, 1, 2, 5 Kim 2002G. amphioetus 1, 2þ4 3þ3 9 2, 2, 1, 2, 5 Iwata & Konishi 1980,

Kornienko & Korn 2010MetacarcinusM. anthonyi 1, 1þ4 3þ3 9 2, 2, 1, 2, 5 Anderson 1978M. gracilis 1, 1þ4 3þ3 9 2, 2, 1, 2, 5 Ally 1975M. novaezelandiae 1, 2þ4 3þ5 10 2, 2, 1, 2, 5 Wear & Fielder 1985M. edwardsii 1, 2þ4 3þ5 10 (ZIII) 2, 2, 1, 2, 5 Quintana 1983M. magister 1, 2þ4 3þ4 10 3, 2, 1, 2, 5 present study

RomaleonR. antennarium 1, 4 3þ3 9 2, 2, 1, 2, 5 Roesijadi 1976R. gibbosulum 1, 2þ4 3þ3 9 2, 2, 1, 2, 5 present studyR. polyodon

(¼ ? Cancer setosus)1, 2þ4 3þ5 9 (ZIII) 2, 2, 1, 2, 5 Quintana & Saelzer 1986


(1977a), C. pagurus by Ingle (1981), and C.plebejus (as C. irroratus) by Sastry(1977b)], and three South Pacific cancridspecies [M. edwardsii by Quintana (1983),M. novaezelandiae by Wear & Fielder(1985), and R. polyodon (as C. setosus) byQuintana & Saelzer (1986)]. Therefore, thismay be an important diagnostic characterfor the identification of planktonic cancridzoeas. Additional common characteristicsin the zoeas of cancrid species are: 1)carapace with rostral, lateral, and dorsalspines, 2) antennal exopod less than halflength of protopod, with two or threeunequally sized terminal setae, 3) basis andendopod of second maxilliped each withfour and 1, 1, 5 setae, respectively, 4) onlysecond pleomere with lateral process, 5)telson fork with two (a lateral stout and adorsomedial) spines, and 6) five zoealstages.

Based on paleontological and morpho-logical evidence of adult cancrid crabs,Nations (1975) divided the genus Cancersensu lato into four subgenera: Romaleon,Glebocarcinus, Metacarcinus, and Cancersensu stricto. Recently, these subgenerawere elevated to full generic status(Schweitzer & Feldmann 2000). Usingzoeal characters such as setation withrespect to the endopods of the maxilluleand the maxilla, basis and endopod of thefirst maxilliped, the zoeal morphology of15 species in four genera is compared(Table 4). Based on zoeal mouthpartssetation, three genera (Romaleon, Meta-carcinus, and Cancer) appear to be hetero-geneous. The present zoeal description ofM. magister agrees well with C. productusand shows more affinity to Cancer zoeasthan those of Metacarcinus. Also, thepresent zoeal description of R. gibbosulumcoincides well with two species of Glebo-carcinus. Therefore, based on zoeal mor-phology, a re-examination of genericassignment based on adult characters ofM. magister and R. gibbosulum should beconsidered.

Acknowledgments

The authors wish to thank Dr. StephenSulkin (Shannon Point Marine Center,U.S.A.) for inviting the second author asa visiting researcher in 2004. This workwas supported by a grant from theNational Institute of Biological Resources(NIBR), funded by the Ministry of Envi-ronment (MOE) of the Republic of Korea(NIBR No. 2013-02-001).

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Documents

Larval stages of Romaleon gibbosulum and Metacarcinus magister (Crustacea: Decapoda: Cancridae) described from laboratory reared materials