On Merocryptoides, a leucosiid crab genus (Crustacea: Decapoda: Brachyura) endemic to Japan, with description of two new species

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ZOOLOGICAL SCIENCE 18i 993-1O02 (2001) @ 2001 Zoologica lSocjety of Japan
Onnaerocryptoides,LeucosiidCrab Genus (Crustacea:
a

Decapoda: Brachyura)Endemic to Japan,

with Description of Two New Species
Hironor iKomatsu" andMasatsune Takeda2
1Department of Biologica lSciences, Graduate School of Science ,7'he Universit yof TOkyo, 7-3-1
Hongo, Bunkyo-ku, Tbkyo 113-O033,
.Lapan
2Department ofZOotogy} tVation aSlcience Museum, 3-23- 1l-lyakuninch oS,hinjuku-ku,
foScy o169-O073 ,Japan, and DepartTnent of Biologica Slciences ,Gtaduate Schoot
ofScience, The Univet:sit yTobifqto ,Z-3-1 Hongo, Buntyo-ku,
fokyo1f3-O033,
,Lapan
ABSTRACT-The taxonomy of the leucosi icdrab genus Merocr)tptoid Seaskai ,1963 is revised, and two
new species, M. ohtsukai and M. peter iare describe dfrom Japan, These new species resemble the type
species of the genus, Atf f.rontal Siaskai 1,963 from Japan, but can be distinguish ferdom i tby the form of the
cardiac tubercle, male abdomen, male telson and firs mtale pleopods .Meroct]tptoid oehstsukaiis also distin-
guishe fdrom M. peter biy the broadl yV-shaped ridge on the gastr tiucbercle, the latera lmargin of the hepatic
region not ridged and the form of the median tooth of the epibranchial margin,
INTRODUCTION abdominal formulae ,which denote the telson and rest of the
fusedabdominal segments, respectively. Allthe specimens

The genus Merocmptoides ,the famil yLeucosiida ew,as examined are deposite din the Nationa lScienc eMuseum,
originally established by Sakai {1963 f)or only one species, Tokyo (NSMT )and the Showa Memorial lnstitut eN,ational
M. ftontabSsakai,1963fromJapan.inMay 2000,thefirst ScienceMuseum, Tokyo (NSMT-R).

author had an opportunity to joi tnhe crui$e of the TRV
TQyoshio Maru of Hiroshima Universit iyn,vestigat itnhge zoo- TAXONOMY
planktoni bce,nthic and nektonic faunae of the Nansei lslands,
southwest Japan, conducted by Dr, S, Ohtsuka, the Associ- Family Leucosiidae Samouelle ,1819
ate Professo rof Hiroshima Universi Dtuyr.ing thi$ cruise, the Genus Merocryptoides Sakai ,1 963
fir satuthor collected many brachyur aspnecimens by dredg- Merocmptoicie Ssakai 1, 963 :220; 1 965: 31 ; 1 976 :78; Serbne,
ing or sledge net$ in the sea from the Seto lnlan dSea south- 1968: 42.
wards to the Kerama lsland aslong the Nansei jsland sA,mong Type species, Merocryptoide fsrontal Siaskai ,1963, by
this material was two specimens belongin gto a new species monotypy,
of Merocoptoides .In addition, another specimen collected Diagnosis C.arapace as long as broad in males, slightly
from off Kisami ,Shimoda, lzu Peninsula c,entral Japan, also broader than long in females ,subrhomboidal, with postirontai,
differe dfrom both the above mentioned species. In this median and epibranchial ridges; upper surface covered with
paper ,we describ etwo new species from Japan and review rounded granules f;ront arlegion distinc tdleyveioped in males,
the taxonomy of the genus Meroct)/ptoid eWse, redescribe with margin cut int otwo lobes ;gastri rcegion with pair of ridge-
M. frontaii sin detai lto clarily the characters of the genus and bearing tubercles ;cardiac region with median tubercie ;intes-
thedifferencbeestweenthisspecies and thenew ones. tinalregion clearly demarcatedt,rapezoidal,without median

Measurements, given in millimeters, are of the greatest ridge; hepatic region well demarcated ,with triangula rfacet
carapace lengt h(inclu dtihne gposteri olrobe )and breadth, present on later aplart; pte rygostomian margin with triangular
respectively,Thedescriptiveterminologygenerallyfollows1hle tooth medially; epibranchial region strongly expanded, with
<1918 i)n,cludin tghe use of the abbreviations T and R forthe transvers es,ubmedian ridge; epibranchiai margin with large,
triangul atrooth on anterior end, formin gacute angle with
metabranchialmargin;metabranchialregiondeeplyconcave;
'Correspondingauthor:Tel, [phone];
FAX. [phone]. later asulrtace of branchia rlegion with three small teeth; pos-
E-mail :[email protected] terio rmargin divide dint othree lobes or undivided. Ocular
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994 H. Komatsu and M.Takeda
peduncle short. Antennule obliquely folded in fossa, basal {3.×43.3) ,allotype, ovig. 4 (4.×45.3) ,NSMT-R-Cr. 3851.
segment occupying about hal fof fos$a .Second segment of Kurosaki ,Sagami Bay; shoal water of tide-pool ;coll. His
antenna subcyljndrical, folde din orbital hiatu swithout gap. Majesty ;Jul.1962 ;paratypes, 28 84 (3.2x3. 31.,4x3,3), 19
Afferen cthannel with weak plicati oBnu.ccal frame with fis- (4.×75.5) ,NSMT-R-Cr, 2703. Kurosaki ,Sagami Bay; shoal
sure at anterior fif thof later amlargin, Maxillut ewithout water ot tide-poo clo;ll. His Majesty ;20 Jul ,1962; 3 ovig, ? ?
endopod. Second maxilliped without exopodal flagellum. (4.×35.2-4.5×5.4) ,NSMT-R-Cr. 2705. 0ff Kisami ,Shimoda,
Basis of third maxilliped completely fused with ischium ,rem- lzu Peninsula 1;8-45 m; coil. K. Nakamura; 23 Aug. 1982; 2
nant suture presen ton intern aslurface; exopod relatively nar- Xr (3,×53.7, 4.8×4.4; both heavil ycovered with mem-
row, angled on posteri eondr of latera lmargin, with vestigial branipor ibdryozoan), 1 ovig. 51 (5.×36.6), 1 juv (.2.×52.7),
intern arlidge. Chelipe dof moderate size; coxal condyle small NSMT-Cr. 10406.
in both sexes; merus subcylindricai, with two triangula rteeth Descriptio Cna.rapace (Fig 1sa,, 4a, b) subrhomboidal in
on outer margin; carpus with two crests on outer su rface o;uter genera loutline, as long as broad in males, 1.2 times broader
margin of palm crested, divide dint otwo lobes ,Ambulatory than long in females ,armed with postfront ameld,ian andtrans-
legs similar in shape; coxal condyles small in males, absent versely running epibranchial ridges; upper surface entirely
in females ;meri subcylindrical, with two triangula rteeth on covered with round, flatten egdranules ,Front strongly pro-
outer margins; outer surtaces of carpi fla tc,rested on both duced, rather deeply concave medially, about O,4 times as
margins; dactylo-propod iaolcks presen ton proxima lborders broad as carapace in males, about O.3 times as broad as cara-
ofdorsalsurtacesofdactyliM.ale abdomen with formula of paceinfemales;margin subtruncate,with smallmedian notch;

1 +2+R+T; fir sstegment transv ersely subrectangular; second postiront raildge beaded, running obliquely from each frontal-
segment transversely narrow; main section composed of com- orbital angle towards midline, separated from each other by
pletel fyused third to sixth segments, elongate trapezoidal, shallow median groove ,Orbita lfissure sa and Bstrai gyht,
with tooth near dista lborder. Female abdomen with formula broadly V-shaped, with suture. Mesogastri cregion longitudi-
of 2+R+T; fir sstegment concealed beneath carapace; sec- nal, broadly convex, continuous from front arlegion, getting
ond segment transversely subrectangular; main section narrower towards cardiac tubercle .Hepati cregion clearly de-
composed of fused thir dto sixth segments, ovate. Firs tmale marcated, rectangular, with triangul faarce otn tater apla rt ,facet
pleopod slender, taperin dgistal lSye,cond male pleopod short, rimmed with ridged row of granules ,Pterygostomia mnargin
about one thir das long as fir sptleopod ,filifo rwmit,h acute tip. convex outwards, with lobula trriangul aprrojecti omnedially,
Remarks. The genus Meroctyptolde wsas originally es- separated from epibranchial margin by U-shaped notch.
tablished by Sakai (196 3as) an allied genus of Merocr)ptus Gastro-cardi arecgion prominentl ryaised, with pair of tubercles
A. Milne Edwards ,1 873. However ,MerDcr)ptold biss actually not on ga$tri rcegion and one tubercle on cardiac region; gastric
close to Meroct)tptus ,but is more similar to a group of small- tubercle with C-shaped ridge that is sometimes fused with
sized species of Nursia Leach, 1819, vii,, N. elegans lhle, epibranchial ridge; cardiac tubercle transversely convex. In-
1918, N, japoni Scaakai ,1935, N. alata Komatsu & Takeda, testina lregion demarcated ,trapezoida el],evated posteriorly,
1999, in lackin gthe endopod of maxillule and an exopodal divide dfrom intestin raelgion by shallow transvers egroove.
flagellu omf the second maxilliped, the presence of a lateral Epibranchi arlegion markedly projecting lateral laynt,eriorly
angle on the third maxillipedal exopod and the form of the slopingfrom epibranchial ridge; margin weakly ridged, straight,
abdomen. Merocmptus has an endopod of the maxillule and obliquely divergin gw,ith larg etriangular ,somewhat down-
an exopodal flagellu omn the second maxilliped <bot shtruc- wards directe pdrojecti oonn anteriormost edge; epibranchial
tures absent in Meroctyptoide sd)oes not have a later aalngle ridge conspicuous, broad in females ,almost transversely
on the thir dmaxillipedal exopod, and has a femal eabdominal straight, extending from near gastri ctubercl eto ti pof
formul aot l +2+R+T(2+R+T in Meroctyptoide s, M)eroctyptoi- epibranchial region, beaded with transverse loyblong gran-
des can, however, be distinguished from these and other ules in males, fla trounded granule isn females. Metabranchial
Nunsia species by the protubera nmatle frontal region, region deeply concave between epibranchial ridge and intes-
possesio onf the transversely radiating epibranchial ridges, tina lregion; margin curved inwards. Lateral surface of bran-
the proportiona lnlayrrowed thir dmaxillipedal exopods and chial region with three small rounded teeth ,anterior two teeth
having bilobe douter margins of the chelipedal palms .The concealed beneath epibranchial projectio ann,terior toot hlarg-
type species and two new species describe dherei nare known est, median tooth inconspicuou sp,osteri otrooth at midlength
only from Japanese waters thus far, of metabranchial margin, Posterio mrargin almost strajght, not
dividedintolobes,obtusely angled with metabranchial mar-

Merocryptoides frontafi Ssakai ,1963 gin.
(Fig $1, .4a, b) Mandible (Fi g1b., c) well calcified c;utting edge triangu-
Meroct],ptoidhesantatSiaskai1,963:220,fig4.[typleocality: larinoutline,pointedmedially;endopodpalpthree-segmented,

Sagami Bay, Japan]; 1965: 32, pl ,14(3), fig .3a, b; 1g76: 79, terminal segment fringed wjth short setae. Maxillule (Fig 1.d):
fig 4,0a, b, pl ,25(6) ;Serbne ,1968: 42, coxal endite subcylindrical, directe dmesially, with some ter-
Materia lexamined. Japan. Arasaki ,Sagami Bay; shoal minal setae; basia iendite triangular ,with stout, thin setae on
water of tide-pool ;coll. His Majesty ;17 Jul .1 962; holotype ,8 mesial margin; endopod absent; epipod small, directe dlater-
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MerocryptoidesL,eucosiidCrabGenusEndemictoJapan 995

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Fig. 1. Merocryptoide sttontal iSsakai ,1963. a-J ,ovigerous female (5.×36.6 mm); k-m, male (4.×84.4 mm) from off Kisami, Shimoda, lzu
peninsul cae,ntra] Japan (NSMT-C r10,406). a, carapace, dorsa lview, b, mandtble, external view; c, same, interna vliew, d, maxillule, external
view; e, maxilla, externai view; f ,fir smatxilliped, external view; g, second maxilliped, external view; h, thir dmaxilliped, external view; i ,same,
interna lview; j ,femaie abdomen, ventral view; k, male abdomen, ventral view; 1 ,fir smtale pleopod ,external view; m, second male pleopod,
external view. Scaie sfo ra and J = 1 mm; scales fo rb-g ,h-i ,k and 1-m = O,5 mm.
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ally. Maxill (aFi g1 e.): coxal endite small, rounded; basia elndite Female thoracic $ternites covered with closely set, ilat-
bilobed w,ith some terminal setae on proxima llobe ;endopod tened round granule sof various sizes; fir stto thir dsternites
weakly bilobed ;exopod (scaphognat hlointgei)tudina lexl-y fused togethe rb,ut deeply concave between remnant fir santd
panded into ovate structure ,entirel fyringe wdith short plumose second segments; abdominai cavity reaching to buccal cav-
setae. Fi rst maxilliped (Fi g1,f) :coxal endite semiglobular, with ern, both margins of abdominal cavity ridged on subdistal part,
dense setae; basia lendite lobula rl,argel eyxpanded int otri- with V-shaped notch.
angular structure, fringe dwith long ,ptumose setae; endopod Male abdomen (Fi gl,k) coarsely covered with pearly
lobula rl,ongitudina lexlpyanded, fitti nign efferent channel, granule ost various sizes, with formula of 1+2+R+T; firs tand
highl yplicat oen upper surface, with short setae along plica- second segments very short, transversely subrectangular,
tion, latera lhalf folded downwards; exopod longitudinally secondsegmentlaterallyconcealed;mainfusedsectionelon-
filifo rwmit,h long setae on dist apalrt of mesial margin, bear- gate ,rhomboidal, composed of third to sixth segments, divided
ing flage)lu wmith long termina sletae. Second maxi11iped (Fig. int osubregions by two longitudin aalnd two transverse
1g) :endopod with long setae along inner margins of ischium grooves ,swollen at both sides of proxima lhalt ,constricted
and merus, with $hort setae along later amlargin of merus, medially and dista olne-third, with larg etooth near dista blor-
densely setose around outer margin of propodus ,dactyius der ;telson broadl ytriangula rwith rounded tip ,slightly con-
fringe dwith stout setae around tip ;exopod filifo rtma,pering stricte dat dista tlhird ,fringed with short setae.
distal lwyi,th long setae on dista lpodion of mesial margin, Female abdomen (Fi gI.D entirel ycovered with closely
withoutflagellum. set,vesiculargranulesofvarioussizes,withformulaof2+R+T;
Third maxilliped (Fi g1h,, i) covered with granule sof vari- fir sstegment completely concealed beneath carapace; sec-
ous sizes; ischium longitudinall cyonvex in later atlwo-thirds; ond segment short, transversely subrectangular, medially
merus slightly bent dorsall iyn $itu, 1 .0-1 .1 times as long as convex poste ro-ventrally; main fused section ovate, composed
ischiu malong mesial margin; exopod relatively narrow: lat- of thir dto sixth segments, moderately convex ventrally, di-
eral margin of exopod sharply angled at proxima lend, fringed vided into subregions by two deep longitudina land three faint
with short plumose setae; intern aelxopodal ridge vestigial. transverse grooves ,slightly convex along midline but lower
Cheliped (Fi gI.a) moderate, 1.0-1,1 times as long as than later arlegjons, marginally rimmed with pearl ygranules
carapace in males, O.9 times as long as carapace in females, except proxima lmargin; telso ntongue-shaped ,fringe dwith
measured along outer margin from merus to ti pof movable short setae around tip d,irecte dantero-dorsally in situ.
finge re,ntirely covered with rounded, sometimes acute gran- Firs mtale pleopod (Fi g11,> slender, sinuate, dista flourth
ules except on finger sc;oxal condyle small, oblong in both directe dmesially, tip curled, setose, mesial and latera lmar-
sexes; merus subcylindrical, bearin gtwo triangula rlobe$ on gin swith soft setae, Second male pleopod (Fi g1,m) short,
dista elnd and midlength of outer margin, dista llobe twice as about one-third as long as firs tone, proxim atlwo-fifth bsroad,
broad as the other, with small submarginal tooth on some- distale rpart filifor mt,ip acute.
what proxima lpositio onf median lobe; carpus short ,with two Remarks. This species clearly shows sexual dimorphism
crests on outer surface; palm convex dorsall yo;uter margin in the front arlegion, with males having a more distinc tdley-
of palm crested, divide dinto two lobes ,dista llobe strongly veloped front arlegion, Also females seem to be generally
convex outwards; finger ssubconical, 1.4-1, 5times as long larger than males.
as palm along outer margin, covered with minute granules; Distributi Joanp.an endemic-Sagami Bay (ty pleocality),
both cutting edges of finger sfinel dyentat eon dista hlalves, lzu Peninsula a,nd Ki iPeninsula O.ccurri nign tide-pool ,rocky
meeting only at tips. beaches, and also at depths of 18-45 m.
Ambulatory legs (Fi g1a.) similar in shape, graduall dye-
creasing in lengt hfrom fir stto fourt hc,overed with granul eosf Mbrocr)tptoide oshtsukei$p. nov.
various sizes and shapes; coxal condyles small, rounded in <Fig 2s, .4c)
males, absent in females; meri subcylindrical ,with small tri- Materia lexamined, Japan. 30015.00'N ,130053,30'E
angular teeth and acutely triangula rteet hat dista elnd and (Wes otf Tanega-shima 1. O,sumi ls. s,outh of Kyushu) ;dredge;
midlength ot outer margins, respectively; carpi triangul airn bottom of sand and dead shells, 47 m; coll. H. Komatsu; 25
cross-section; outer surfaces of carpi fla tc,rested on both May 2000; holetyp e8,i (3.×53.6), NSMT-Cr, 14184; paratype,
margins; propod irather compressed, weakly crested on outer 8 (3.×73.5; heavily covered with membraniporid bryozoan},
margins; dacty lsiubconical, $lightly incurved ,with obvious NSMT-Cr. 14185.
dactylo-propod laolcks on proxima lborder sof dorsa lsurtaces, Description of holotype. Carapac e{Fig s2a., 4c) subrhom-
covered with microscopic granules ,inne rmargins finel dyen- boida lin general outline, as long as broad, armed with
tate. postiront amle,dian and epibranchial ridges; upper surface
Malethoracicsternitescoarselyceveredwithpearlygran- entirelycoveredwithcloselyset,roundgranules.Frontstrongly
ules of various sizes, deeply concave between sternites, produced ,rather deeply concave medially; margin divide dinto
episternites not dMded entirely ;firs tto thir dsternites fused two iobes by median, broad V-$haped notch; posttront raildge
together ;abdominal cavity reaching to buccal cavern, not running somewhat obliquely from each frontal-orb iatngalle
ridged on margin. towards midline, Orbita tlissure a short, B moderately long, y
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Merocmptoides,LeucosiidCrabGenus Endemic toJapan 997

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Fig .2. MerDctyptoide sohtsukaisp. nov. Holotype ,male (3.5x3 m.m;6 NSMT-Cr, 141 84) from off Tanega-shima lsland ,Osumi lslands s,outh-
western Japan. a, carapace, dorsa lview; b, mandible, external view; c, same, intern vaielw; d, maxi11ule, external view; e, maxilla, external view;
f ,fir smtaxilliped, exiernal view; g, second maxilliped, exiernal view; h, third maxilliped, external view; i ,same, interna vliew; j ,right cheliped,
dorsal view; k, right f rist ambulatory leg ,dorsa iview; l ,abdomen, ventral view; m, right fir sptleopod ,external view; n, same, mesial view; o, right
second pleopod, external view. Scales fora and 1 =1 mm; scales for b-i ,i- aknd m-o =O,5 mm,
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broadly V-shaped, with suture. Mesogastric region convex long as palm along outer margin, covered with minute gran-
dorsally ,longitudinal ,continuous from frontal region, getting ules, weakly ridged on midline ot movable finge rb;oth cutting
weaker towards cardiac tubercl ew,ith rather deep concavity edges of finger asrmed with some irregula fri,n eteeth on each
behind fronta lregion. Hepati cregion clearly demarcated, dist ahlalf ,meeting only at tips.
rectangular, with triangula rfacet on later aplart ,rather slop- Ambulatory legs (Fi g2.k) similar in shape, gradually
ing anterolaterally, ridged on anterior margin of facet only, decreasin gin lengt hfrom fir stto fourt hc,overed with pearly
with distin cltarg egranul eon center. Pterygostomia mnargin granule sexcept dactyi ic;oxal condyles small, oblong; meri
convex outwards, ridged, with lobular ,triangul avren,trally pro- subcylindrical, with two triangula rIobes on dista lend and
jecti ntgooth medially. Gastro-cardia cregion prominently midlength ot outer margins, lobes gettin wgeaker from f rist to
raised, separated from intestin raelgion, with pai rof tubercles fourt hlegs ,with larg etriangula rlobe on midlength of inner
on gastri cregion, with broadl yV-shaped ridges on gastric margininfourthlegonly;carpitriangularincross-section;outer
tubercle sc;ardiac region with prominen ttubercle, with me- surtaces of carpi fla tc,rested on both margins, beaded on
dian Iongitudi nraidlge. tntesti nraeglion rectangular in outline, lower crests; propod icompressed, crested on outer margins;
elevated posterior lcyre,sted marginally. Epibranchi arlegion dactylisubconical,slightlyincurved,coveredwithmicroscopic
markedly projectin glaterally ,anteriorly sloping from granules ,with obvious dactylo-propod allocks on proximal
epibranchial ridge; margin entirely rimmed with thin ,almost border sof dorsa lsurfaces, inne rmargins finel dyentate.
fused, beaded lin ewhich is continuous to epibranchial ridge, Thoracic sternites coarsely covered with closeiy set,
forming right angle with pterygostomia mnargin, bearin glarge pearlygranul eofs various sizes, deeply concave between ster-
triangula rlobe on anterior third and small triangula rlobe on nites, episternites not divided entirely; firs tto third sternites
midlength, formin gacute angle with metabranchial margin; fu$e dtogether a;bdominal cavity reaching to buccal cavern;
epibranchial ridge conspicuous, almost transversely straight, both margins of abdominal cavity ridged on subdistal part,
extending from near gastri tcubercle to tip of epi-metabranchial with V-shaped notch.
angle. Metabranchia lregion deeply concave between Abdomen (Fi 2g1. )enti rely covered with small round gran-
epibranchia lridge and intesti nraeglion; margin cu rved inwards. u1es,withformulaof1+2+R+T;firstsegmentshort,transversely
Lateral surface of branchia lregion bearin gthree small, trian- subrectangular; second segment very $hort, transversely
guiar teeth; anterior tooth larges tc,oncealed beneath median narrow, laterali yconcealed; main fused section elongate,
tooth of epibranchial margin, median tooth $ituated at ante- rhomboidal, composed of third to sixth segments, both sides
rior third of metabranchial margin, posteri otrooth on midst of of proxim ahlalf swollen, concave between swollen regions,
metabranchial region. Posterior margin divided into three parts; butgraduallybecomingconvexalongmidlinedistally,highest
each latera lpar tlobular ,triangula rwith rounded tip ,weakly at proxima lthree-fourths length c,onstricted medially and dis-
sloping posterolatera lwliyth, margin continuous to meta- talone-third,bearinglarge,triangular,directedposteriorlytooth
branchial margin; median part broadl ysemicircular, situated near dista blorder ;tel$on acutely triangula rwith rounded tip,
Iower than later allobes, fringe dwith short setae.
Mouth parts {Fi g2,b-g) closely resembling those of M Firs tpleopod <Fi g2m., n} slender, bent medially almost
hantali sb,ut differe anst follow sM,axill a(Fi 2ge,): coxal endite at a right angle, with long soft setae on proxima lhal fof lateral
very small; basia lendite triangular ;endopod rounded. First margin and short, stiff setae at dista tlhir dt,i ptranslucent,
maxilliped (Fi 2gf.) :endopod lobula rl,ongitudina elxlpyanded, arcuate, Second pleopod (Fi g2,o) short, about one-third as
fitti ngin efferent channel, weakly plica toen upper surface, Iong as firs ptleopod ,proxjma ltwo-fifth sbroad ,distal eprart
with $hort setae along plication, filifo rtimp, acute triangular w,ith some long ,soft setae at proxi-
Third maxilliped (Fi 2gh,, i )covered with pearl ygranules mal part of mesial margin.
ot various sizes; ischium longitudina clolnyvex in later atlwo- Color .In $pirit ,whole body off white, symmetrically speck-
third sm;erus slightly bent dorsall iyn situ, 1 ,2 times as long as Ied with dark brown and orange spots of various shapes and
ischium along mesial margin; exopod relatively narrow, with sizes. Spots variable by each individual,
three or four subacute granuie son dista piart ;later amlargin Etymology .This species is dedicated to Dr. Susumu
ot exopod sharply angled at posteri oernd, fringe dwith short Ohtsuka,theAssociateProfessorofHiroshimaUniversity,who
plumose setae; intern aelxopodal ridge vestigial, gave the flr satuthor an opportunity to collect crabs on board
Chelipe (dFi g2j, )as long as carapace, entirely covered the TRV TQyoshio Maru.
with pearly s,ometimes acute granuie exscept on finger sc;oxal Remarks, The type specimens of Meroctyptolde oshtsukai
condyle smaM, transversely ovate; merus subcylindrical, bear- sp. nov, were collected by dredgin gfrom off Tanega-shima
ing two $ubequal, triangul laorbes on dista elnd and midlength lsian dt,he Osumi lsland sj,us stouth of Kyushu, southwest-
of outer margin, submarginally with small, triangula rlobe at ern Japan, at the depth of 47 m, The specimens closely re-
somewhat proxima lpositi oonf median lobe; carpus short, with semble angular fragments of dead shells or pebbles of the
two cre$ts on outer su rface u,ppersurface bearing row of sub- bottom ,The new species is closely similar to M, peter isp.
acute round granule son midline; palm convex dorsall yo;uter nov, in having a longitudina clolnvyex cardiac tubercle, a lon-
margin of palm crested, divide dinto two lobes, dista llobe gitudinal cloynvex male abdomen and a medially bent first
strongly convex outwards; finge rssubconical, 1.3 times as male pleopod .However, M. ohtsukaican bedistinguished from
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Merocmptoides,LeucosiidCrabGenus Endemic toJapan 999

aij.#.
,
"s...,.,

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ttt
b
tttt
e
1-/,,,;,.t-
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1
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･
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o
Fig. 3. Metocmptoidespeteri sp, nov. Holotype ,male (3.9x3 m.m9; NSMT-Cr, 9177) from off Kisami ,Shimoda ,Izu Peninsula ,central Japan.
a, carapace, dorsa lview; b, mandible, external view; c, same, intern avliew; d, maxillule, external view; e, maxi11a, external view; f ,firs mtaxilliped,
external view; g ,second maxilllped, external view; h, third maxilliped, external view; i ,same, intern avliew; j ,right cheliped, dorsa lview; k, right
iirs atmbulatory leg ,dorsa lview; 1 ,abdomen, ventral view; m, right fir splteopod, external view; n, same, mesial view; o, right second pjeopod,
external view. Scales for a･j･ kand 1 =1 mm; scales for b- iand m-o =O,5 mm.
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1OOO H. Komatsu and M, Takeda
M. peter iby the shape of the ridge on the gastri ctubercle gion deeply concave between epibranchial ridge and intesti-
(se eFig .2a and 3a) ,the unridged later amlargin of the he- nal region; margin curved inwards .Latera lsurface of bran-
paticregion and the presenceof a median tooth on the chialregion bearingthreesmall triangularteeth;ante riortooth

epibranchialmargin, slightl yvisible between projectio nosf epibranchial margin;
ln turn, these two new species can be distinguished from median tooth concealed beneath epi-metabranchial angle;
M. hantali bsy that ;1) the cardiac tubercl eis longitudinally posteri otrooth at midlength of metabranchial margin. Poste-
convex, with a median ridge, whilst tha tot the latt esrpecies is rior margin divide dint othree parts l;ater aplart slobula rt,rian-
transversely convex; 2) the male abdomen is highl yconvex gular with rounded tip ,weakly sloping postero-latera liltys,
along the midline in the main fused section, whilst that of the margin continuous to metab ranchial margin; median par tsemi-
latterisnot convex medially; 3)themale telsonisacutely tri- circular,situated slightlylowerthanIaterallobes.

angular, whilst that of the latt eirs broadl tyriangular ;and 4) Mouth part s(Fi g3.b-g) closeiy resembling those of M.
the fir $mtale pleopod is bent medially at a right angle, whilst fronta tbiust ,differe nats follow sM.axill a(Fi g3,e) :endites
those of the latte ris sinuate, with a medially directe dc,urled mis$ing. Firs tmaxilliped (Fi g3.f) iendopod lobula rl,ongitudi-
tip. nally expanded, fitti nign efferent channel, highi yplicat oen
The comparisons of three species of Meroctyptoide sM,, upper surtace, with short setae along plicati odni,sta plart of
frontat Siaskai ,M, ohtsukaisp, nov, and M, peterisp n,ov,, are later atlhird internal floylded.
summarized in Table 1. Thjrd maxilliped (Fi g3h., i )covered with pearl ygranules
Distributio nK,nown only from off Tanega-shima lsland }n of various sizes; ischium longitudinall cyonvex in latera ltwo
the Osumi lslands(typelocality)s,outhwestern Japan, 47 m thirds;merus slightlybentdorsallyinsitu,1.1timesas longas

deep, ischiu malong mesial margin; exopod relatively narrow; lat-
eral margin of exopod sharply angled at posterio ernd and
Merocryptoides peter isp. nov. fringe wdith short plumose setae; intern aelxopodai ridge ves-
(Fig 3s, .4d) tigjal,
Materia elxamined, Japan, Off Kisami ,Shimoda, lzu Pen- Chelipe d(Fi g3D, moderate, 1,t times as long as cara-
insula ;18-45 m; coll. K. Nakamura; 23 Aug, 1982; holotype, pace, entirejy covered with pearly, sometimes acute granules
8 (3.×93,9) ,NSMT-Cr. 91 77. except on fingers ;coxal condyle small, rounded; merus
Descriptionofholotype.Carapace{Figs.3a,4d)subrhom-subcylindricai, bearin gtwo subequal, triangul alrobes on dis-
boida lin general outline, as long as broad, armed with ta lend and midlength of outer margin, submarginally with small
postfront amle,dian and epibranchjal ridges; upper surface triangula rlobe at somewhat proxima lpositi oonf median lobe;
entirely covered with closely set, round granules F.ront strongly carpus short, with two crests on outer surface, upper surface
produced ,rather deeply concave medially; margin divide dinto bearin grow of pearl ygranule son midline; palm convex dor-
two lobes by a median, broad V-shaped notch; postirontal sally; outer margin of palm crested, divided into two lobes,
ridge running somewhat obliquely from each frontal-orbital distallobestrongly convex outwards; fingerssubconical, 1.3

angle towards midline. OrbitaHissur ae short, 6 moderately times as long as palm along outer margin, covered with minute
long ,y broadl yV-shaped, with suture. Mesogastri cregion lon- granules ;both cutting edge$ of finger sarmed with some
gitudinal cloynvex, contjnuous from front alregion, getting sparse, fin eteeth on dista hlalves ,meeting only at tips.
weaker towards cardiac tubercl eH,epatic region ciearly de- Ambulatory legs (Fi g3k.) similar in shape, graduall dye-
marcated, rectangular, with triangularfaceton lateraplart, creasing inlengthfromfristtotourthc,overed with pearlygran-

rather slopinglaterallriyd,ged on ante riorand lateramlargins. ules except dactylcio;xal condyles small, rounded; meri

Pterygostomian margin convex outwards, ridged, with lobular subcylindrical,with two triangularlobes on distalend and

triangul atroot hmedially, toot hprojecti nvgentrally, Gastro- midlength of outer margins, lobes getti nwegaker from f irst to
cardiac region prominent lrayised, divided from intestinal fourth legs so as to be absent in fourth leg; carpi triangula rin
region, with pair of tubercles on gastri rcegion, with Y-shaped cross-section; outer surfaces of carpi flat ,crested on both
ridge on tubercles ;mesial branch of Y-shaped ridge straight, margins, beaded on lower margins; propod icompressed,
parall ewlith midline, later ablranch directe danterolaterally; crestedonoutermargins;dactylisubconical,slightlyincurved,
cardiac region with longitudina lcolnyvex tubercle, with weak covered with microscopic granules ,with obvious dactylo-
median ridge. Intestina lregion demarcated, trapezoidal, propoda llocks on proxima lborders of dorsal surfaces, inner
elevatedposteriorlEyp.ibranchiarlegion markedly projecting margins fineldyentate.

laterall ya,nteriorly sloping from epibranchial ridge; margin Thoracic sternites coarsely covered with clo$ely set,
entirely rimmed with almost fused togethe rbeaded Iin ewhich pearly granule sof various sizes, deeply concave between ster-
is continuous to epibranchial ridge, formin gright angle with nites, episternites not divide dentirely; fir stto thir dsternites
pterygostomianmafgin,bearinglargetriangularprojectionfounsed together a;bdominal cavity reaching to buccal cavern;
anteriorhalf,obliquelydiverginginposteriorhalf,formingacute both margins of abdominal cavity ridged on subdistal part,
anglewithmetabranchialmargin;epbranchialridgeconspicu- with V-shaped notch,
ous, almost transversely straight, extending from near gastric Abdomen <Fi 3g1,) entirely covered with small round gran-
tubercle to tip of epi-metabranchial angle. Metabranchia lre- ules,withformulaof1+2+R+T;firstsegmentshort,transversely
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MeroctyptoidesL,eucosiidCrabGenus EndemictoJapan 1001

Fig. 4. A, B, Merocmptoid etstonta Staskai 1,963, male {NSMT-C r1.0406; 4.8×4.4 mm; A) and ovigerous femal e<NSMT-C r1.0406; 5,3x6.6
mm; B); C, Meroctyptoici eohstsukaisp, nov., holotype ,male (NSMT-Cr .141 84; 3,5×3.6mm); D, Meroct)ptoiclespeteri snopv.., holotype ,male
(NSMT-C r9.177; 3.9x3.9 mm). A, B and D from off Kisami ,Shimoda ,lzu peninsula ,central Japan; C from off Tanega-shima lsland ,Osumi
lslands s,outhwestern Japan.
subrectangular;secondsegmentveryshort,transverselynar- border ,tooth directe dsomewhat posterior ltye;lso nacutely
row, laterall cyoncealed; main fused section elongate, rhom- triangul awirth rounded tip f,ringe dwith short setae.
boidal ,composed of third to sixth segments, both sides of Firs tpleopod (Fi g3,m, n) slender, bent almost at a right
proxima lha) fswollen, concave between swollen regions, but angle medialIy, with long soft setae on proxima lhal fof lateral
gradually becoming convex along midline distat lhyi,ghes tand margin and short stif fsetae on dista lhalf ;tip translucent,
demarcated at proxima lthree-fourths length ,constricted weakly arcuate, Second pleopod {Fi g3o,) short, about one-
medially and dist aonle-third ,bearin glarg etooth near distal third as long as tirs tpleopod ,proxima lthird broad ,distaler
Table1. The comparison between Merocryptoide sfrontati sSakai ,1963, M, ohtsukaisp. nov. and M, peter sip. nov,
M, frontal iSsakaj M. ohtsukai sp. nov, M. peter isp, nov.
Gastrictubercle with C-shape dridge with broadly V- with Y-shaped ridge
shaped ridge
Cardia tcubercle transversely convex longitudinallyconvex longitudinall yconvex
Epibranchialmargin with anterior lobe with anterior and with anterior lobe
small median Iobes
Male abdomen main section not main section strongly main section strongly
convex along convex along midline, convex along midline,
midline, telson telson acutely telsonacutely
broadlytrianguiar triangular triangular
Firs tmale pleopod sinuate, dista plart slender, bent slender, bent
directe dmesially, tip medially, tip arcuate medially, tip weakly
curled arcuate
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1O02 H, Komatsu and M. Takeda
part filito rtmi; pacute, directe rdather laterally. Komatsu H, Takeda M ( 1999) A new leucosii cdrab of the genus Nutsia
Color .In preserv ecdondition ,whole body off white, with from the Ryukyu lslands ,Bul lNatn Sci Mus Tokyo, Ser A, 25:
ligh tbrown spots on front arlegion and midst of metabranchial L ea c5h9 -W6E4 (181 7T)he Zoologjca lMisce[lany ,Being Description osf
reglon, New or lnteresti nAgnimals ,Volume 3, London
Etymology .This species is dedicated to Dr, Peter K. L MilneEdwardsA(1873)DescriptiondequelquesCrustacesnouveaux
Ng of the Nationa lUniversity of Singapore ,who generally ou peu connus provenant du Musee de M. O. Godeffroy .J Mus
supported and helped our study. Godeffroy1( 477)-:88, pls .1, 2
Remarks. The holotyp eof Meroctyptoidespete srp.i nov, Saka" iMTi s(a1g9o3" 5dNu)erwi nogr trhaereZ ospoelcoiegsi coaf lBSruarcvheyuyraar ,ocoulnldecttheed lbzyu t-hPeeninsula,
was collected with it scongener, M. frontaf ibsy, dredgin goff Sci Rep Tokyo Bunrik Daaigak uS,ec B, 2: 63-88, pls .6-8
Kisami, Shimoda, lzu Peninsula c,entrat Japan, at the depth Sakai T (196 3D)escriptio oni two new genera and fourteen new spe-
of 18-45 m, Merocryptoide pseter ican be, however, readily cies of Japanese crabs from the collection of his Majest ythe
distinguish ferdom M. frentat aiss mentioned in the remarks of Emperor oi Japan. Crustaceana 5: 21 3-233
M. ohtsukai. Sakai T ( 1965) The crabs ot Sagami Bay collected by His Majesty
The comparisons of three species of Merocmptoitle asre S a kaT hiTe (E m19p7e6r) oCrr oafb Js aopfa Jna, pMaanr uaznedn ,t hTeo kAydojacent Seas, Kodansha,
summarized in Table 1. Tokyo [l n3 volumes]
Distributi Konno.wn only from off Kisami {typ elocality), Samouell eG <181 9T)he entomologists' useful compendium; or an
Shimoda, lzu Peninsula, central Japan, 18-45 m deep. introduct tioo tnhe knowledge of Britis lhnsects ,comprising the
best means of obtaining and prese rving them, and a description
oftheapparatusgeneraMyused;togetherwiththegeneraofLinne,
ACKNOWLEDGMENTS and modern methods of arranging the Classes Crustacea,
Myriapoda, spiders, mites and insects f,rom their affinjties and
The authors wish to express our cordial thanks to the staff of the structure, according to the views ot Dr. Leach. Also an explana-
TRV foyoshio nlaru ot Hiroshima Universit aynd all the members tio nof the terms used in entomology; a calendar of the times of
joini tnheg cruise for their support. We are indebted to Dr. Peter K. L. appearance and usual situations of near 3,OOO species of British
Ng of the Nationa lUniversi toyf Singapore and Dr. Susumu Ohtsuka lnsects ;with instructie fnosr cotlecting and titti nugp objects tor
of Hiroshima Universit fyor their reading and improving our manu- the microscope, Thomas Boys, London
script, Our gratetu tlhanks are due to Dr. Hiros hNiamikawa of Showa SerOne R (196 8Th)e Brachyura of the 1ndo-West Pacifi cregion, Spec
Memerial lnstitu tNea,tiona lScience Museum, Tokyo, for providing pub lSingapore nat Acad Sci 1: 33-"2
us the specimens,
(ReceivMeadrch 22,2001tAcceptedJune20,2001)

REFERENCES
lhleJEW (19j8Di)e Decapoda BrachyuraderSiboga-Expedition1,11.

Oxystomat aC:alappida Lee,ucosiidae R,aninidae ,Siboga-Exped
39b: 159-322
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