A New Fresh water Crab Of The Genus Geothelphusa (Crustacea, Decapoda, Brachyura, Potamidae) From Kagoshima Prefecture, Southern Kyushu, Japan

7 Pages·1994·2 MB·English

by  H Suzuki

PROC. BIOL. SOC. WASH.
107(2), 1994, pp. 318-324
A NEW FRESHWATER CRAB OF THE GENUS
GEOTHELPHUSA (CRUSTACEA: DECAPODA:
BRACHYURA: POTAMIDAE) FROM KAGOSHIMA
PREFECTURE, SOUTHERN KYUSHU, JAPAN
Hiroshi Suzuki and Eiji Tsuda
Abstract.—\ new freshwater crab, Geothelphusa exigua, is described from
Kagoshima Prefecture, southern Kyushu, Japan. It is differentiated from G.
dehaani (White 1847) and G. candidiensis Bott, 1967, in possessing distally
narrowed eyes, presence ofgranules both on the lower edge of the epistome
and on the groove between the subhepatic and pterygostomian regions, and
laterally curved male first gonopod with a subterminal genital opening. This
is the second species known from the Japanese mainland.
AmongtheeightspeciesofthegenusGeo- University, Kagoshima (KUMB) and the
thelphusa known from Japan, G. dehaani Kitakyushu Museum of Natural History,
(White 1847) is the only species known to Kitakyushu(KMNH).Measurementsshown
occur on the Japanese mainland (north of in parentheses under '"Materialexamined"
Honshusouthwardto Nakano-shimaofthe indicate the maximum carapace width in
Tokara Islands, south ofKyushu) (de Haan millimeters. Abbreviationsusedinclude: Cr
1835; White 1847; Stimpson 1858; Rath- andcr, Crustacea; IvR, Invertebrate Recent.
bun 1898, 1904, 1905; Miyake&Chiu 1965;
Miyake & Minei 1965; Bott 1967, 1970;
Family Potamidae Ortmann, 1896
Minei 1973, 1974b). The other seven spe-
Genus Geothelphusa Stimpson, 1858
cies, G. obtusipes Stimpson, 1858, G. saka-
Geothelphusa exigua, new species
motoana{KdUhhxm, 1905), G. aramotoiMi-
nei, 1973, G. tenuimana (Miyake & Minei Figs. 1-3
1965), G. levicervix{Kdiihhxm 1898), G. can- Material examined.—KAmotsuki River:
m
didiensis Bott, 1970, and G. miyazakii(Mi- Futamata-gawa, 400 ah., 1 1 Jul 1991; 7
yake & Chiu 1965), are restricted to the 5 (13.1-21.8), 3 9 (12.2-13.0), holotype, 3
RyukyuIslands, includingAmamiohshima. (21.0), NSMT-Cr 11314, KUMBcr 1039,
Duringourcurrentstudyofthegeograph- KUMBcr 1041: Iwaya-gawa, 220 m ah., 25
ical distribution of G. dehaani in southern Sep 1991; 1 3(20.5), KUMBcr 1042: Nana-
m
Kyushu, unusual specimens ofa freshwater tsudani, Kushira-gawa, 400 alt., 11 Jul
crab ofthe genus Geothelphusa were found 1991; 1 S (18.8), 2 2 (13.2, 13.4), KUMBcr
PorneftechteurOeh.sTuhmeiunPuesnuianlsuelyaesoafndKamgaolsehifimrsat m104al1t.:,Ta2k2aOkcutma19v9a1l;ley1,6Ku(s1h6i.8r)a,-gKaUwaM,B1c8r0
m
gonopods ofthese crabs indicate that they 1045: Naganomaki, Aira-gawa, 180 alt.,
represent a new species which is herein de- 1 1 Jul 1991; 6<5(13.3-22.6),42(15.9-24.4),
scribed and illustrated. KMNH-IvR 900001-900004, KUMBcr
Theholotype isdeposited in the National 1041. Honjo River: Sarugajo valley, 150 m
Science Museum, Tokyo (NSMT), and the alt., 22 Oct 1991; 1 3(19.6), KUMBcr 1045.
paratypes are in the Marine Biological Lab- Ohsumi Kamino River: Hangaishi, 300 m
oratory, Faculty of Fisheries, Kagoshima ah., 25 Sep 1991; 1 3(20.8), KUMBcr 1042.
VOLUME 107, NUMBER 2 319
O River: Onigauto, Fumoto-gawa, 300 m present on lower edge of epistome, absent
alt, 9 Aug 1989; 3 S (11.2-14.8), 2 2 (16.2, medially. Lower orbital margin and groove
17.8), KUMBcr 1038, KUMBcr 1040: between subhepatic and pterygostomian
m
Uchinomaki, Shibatate-gawa, 380 alt., 9 regions lined with small rounded granules.
Aug 1989; 2 S (12.6, 14.3), 4 2 (13.0-28.7), Eyestalk short, proximallly swollen, dis-
KUMBcr 1040: Shinden, 330 m alt., 25 Sep tally slim (Fig. la, b). Corneasmall, slightly
1991; 1 (5 (18.7), KUMBcr 1042: Ohfuji- wider than distal portion ofocular pedun-
m
gawa, 520 alt., 9 Aug 1989; 2 2 (12.7, cle.
26.7), KUMBcr 1040: Ohtakeno, Akase- Merus ofthird maxilliped broad, square,
m
gawa, 600 alt., 9 Aug 1989; 1 young(6.9), with deep punctum (Fig. Ic). Three-seg-
2 S (8.7, 17.8), 3 2 (13.9-15.6), KUMBcr mentedpalpconnectedoninnerdistalangle
1037, KUMBcr 1040. Hirose River: Ma- ofmerus,tipofpalpnotbelowdistalmargin
m
gome, 450 alt., 2 Oct 1991; 1 2 (24.7), ofischium. Exopod slender, longer than is-
KUMBcr 1043. Kubota River: Himekado, chium, with small flagellum (Fig. Ic, d).
1160402m. Falut.n,a2m5aSeRpiv1e9r9:1G;o1r3o(g2a0.m4o)t,oK,U3M8B0cmr 13C.0hemlimpedcsaraapsaycmemewtirditchal(riignhtmlaalregesr tohvaenr
alt.,20ct 1991; 15(9.9), 12(19.0),KUMBcr left in 26 out of 28 males, left larger than
m
1043. HitotsutaniRiver: Uchinoura, 390 right in remainder), symmetrical in all fe-
alt., 2 Oct 1991; 1 5 (16.7), KUMBcr 1043. malesandinmaleslessthan 13.0mm; large
m
Ohura River: Uchinoura, 300 alt., 8 Oct chela 2.09 (1.82-2.27) times aslongas high
1991; 1 S (14.4), KUMBcr 1044. Hetsuka (Fig. le), palm smooth and surfaces rela-
m
River: Sarutubo, 490 alt., 8 Oct 1991; 1 tively rounded, fingers with 2 longitudinal
S (25.0), 1 2 (27.5), KUMBcr 1044: Doh- ridges on outer lateral surface (Fig. le, f).
m
gabaru, 180 alt., 8 Oct 1991; 1 <5 (16.4), Carpus of large cheliped slightly smooth,
KUMBcr 1044. with stout innertooth belowwhich is a low
All specimens were collected by H. Su- swelling (Fig. 2a). Carpus ofsmall cheliped
zuki and E. Tsuda. withoutanyswellingbelowstoutinnertooth.
Diagnosis.—Male first gonopod saber- Palp ofmandible 3-segmented (Fig. 2b),
like, penultimate segment slightly curved distalsegmentuniramousandsickle-shaped,
laterally, ultimate segment strongly curved mediansegmentlongerthanwide,distalhalf
laterally, tapering, genital opening subter- expanded, proximal segment short, stout.
minal. Ocularpeduncleswollenproximally, Adult male first gonopod saber-like (Fig.
cornea small. 2c-h), penultimate segment slightly curved
Description. —Carapace much broader laterally, synovial membrane short, about
than long, smooth and devoid ofhair (Fig. 3 times as long as broad (Fig. 2c), ultimate
la), postfrontal and postorbital regions in- segment strongly curved laterally (Fig. 2c,
distinctly rugose, faint oblique striae on d), tapering, with genital opening subter-
epibranchialandposterolateralregions,epi- minal in position (Fig. 2e). Tip offirst gon-
mm
and uro-gastric regions distinct, former di- opod papilla-like in specimen 8.7 car-
vided into two partsby median depression, apace width (Fig. 2f), and tapered in
mm
cervicalgrooveobsoleteon epibranchialre- specimens 11.2and 14.6 carapacewidth
gion. Anterolateral margin ofcarapace cris- (Fig. 2g, h). Male second gonopod slender,
tate, lined with fine rounded granules, epi- flat, weakly convex, with small lamella on
branchial notch rudimentary. Frontal distal one-third (Fig. 2i, j).
margin 0.35 (0.33-0.40 in male, 0.31-0.38 Sizes (carapace width).—yiaXes, 8.7-25.0
in female) times as broad as carapace. Pos- mm; females, 12.2-28.7 mm.
teriormarginofepistomedividedintothree Color in ///e.—Chocolate brown or dark
partsby 2 deepernotches(Fig. lb), granules brown with scatteredblack speckles on car-
320 PROCEEDINGSOFTHE BIOLOGICALSOCIETY OFWASHINGTON
biC, di e, fjlOmm
Fig. I. Geothelphusaexigua, newspecies, male holotype(NSMT-Cr 11314): a, dorsal view; b, frontalview;
c, third maxilliped, frontal view; d, exopod ofthird maxilliped, frontal view; e, right cheliped, lateral view; f,
fingers, ventrolateral view.
VOLUME 107, NUMBER 2 321
Fig. 2. Geothelphusa exigua, new species, male holotype (NSMT-Cr 11314): a, carpus ofright cheliped,
dorsal view; b, rightmandibularpalp, ventralview; c, left firstgonopod, dorsal view; d, same, ventral view; e,
(diKstUaMlBpcarrt1o0f37s-a1m0e3,9)d:istf,allefvtiefiwr;stig,olnefotpsoedc(o8n.d7 gmomnopcoadr,apadcoerswaildtvhi)e,w;vejn,trsaalmev,iewv;engt,raslamveie(w1.1.M2amlempcaarraatpyapcees
mm
width), ventralview; h, same (14.6 carapace width), ventral view.
E
322 PROCEEDINGSOFTHE BIOLOGICALSOCIETY OFWASHINGTON
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1 1
Fig. 3. Map showingthe distributionand abundance ofG. exigua, new species (black part)and G. dehaani
(white part) in Ohsumi Peninsula, Kagoshima. Arabic numerals corresponding to size ofcircles in the square
at bottom right indicate the numbers ofcrabs captured perten minutes by one person. Broken line shows 150
m contourline.
VOLUME 107, NUMBER 2 323
apace and pereopods. Palm ofchelae choc- subhepaticandpterygostomianregionsalso
olate brown, fingers milk white. No color differentiates G. exigua from G. dehaani.
variation between sexes and sizes. The carapace and pereopods ofG. dehaani
Etymology.—The specific name is de- show color variation, for example red, or-
rived fi-om the Latin "exiguus" (small), al- ange, blue, brown,purple, oryellowishwhite
luding to the small cornea, characteristic of (Chokki 1976, 1980;Suzuki&Tsuda 1991).
the new species. The palm and fingers of G. dehaani, how-
Remarks.—Thesaber-like malefirstgon- ever, are usuallyyellowish white, regardless
opodandthe 3-segmentedmandibularpalp ofcarapacecolor. In G. exigua, thecarapace
withanuniramousdistalsegmentdisplayed and pereopods are chocolate brown ordark
by the new species are characteristics ofthe brown, and only the fingers are milk white.
genus Geothelphusa (see Bott 1970). The In addition, allelic substitution was ob-
medium-sized carapace, smooth palm, and served at General protein-1 and -2, Lactate
broad frontal region ally the specieswith G. dehydrogenase, and Isocitrate dehydro-
dehaaniand G. candidiensis, from which it genase-2 loci between G. exigua and G. de-
is distinguished by several features. haani (Suzuki & Tsuda, pers. comm.).
The most definitive differences may be Distribution.—The specimens of G. exi-
seen on the male first gonopods. The ulti- gua examined have been obtained only in
mate segment in G. dehaani and G. candi- theareaabove 150maltitudeonTakakuma
diensisisstraightorslightlycurvedmesially Mountain, Inao Peak, and Kunimi Moun-
(Bott 1967, 1970;Minei 1973, 1974a), end- tain Ranges, in Ohsumi Peninsula, Kago-
ing in a papilla-like tipwith a terminal gen- shima Prefecture (Fig. 3), where the Mio-
ital opening. In the new species, however, cene granitic rock and quartz porphyry are
this segmentis stronglycurvedlaterallyand exposed. Geothelphusa exigua and G. de-
tapering,havingasubterminalgenitalopen- haani are sympatric, having been taken to-
ing. The eyestalks in both related species gether at many locations.
areconstrictedatthemiddle,andthecornea
andtheproximalpartoftheocularpeduncle
Acknowledgments
are swollen. In the new species, only the
proximal part of the ocular peduncle is We thank K. Baba of Kumamoto Uni-
swollen, the cornea and the distal part of versity, C. L. McLay of the University of
the peduncle are proportionately narrower. Canterbury, and M. Tiirkay of the Natur-
The postorbital and epibranchial regions of museum und Forschungsinstitut Sencken-
the carapace bear finely crenulate striae in berg, fortheircritical readings ofthe manu-
G. candidiensis(see Minei 1973), instead of script. Thanks are also extended to P. K. L.
faint striae as in G. exigua. Examination of Ngand R. Lemaitre fortheirvaluable com-
We
specimens of G. candidiensis reported by ments on the manuscript. are also in-
Minei (1973), and now in the collection of debted to M. Takeda of National Science
the Kitakyushu Museum of Natural His- Museum, for his comments and to M. Ota
tory, Kitakyushu (5 <5, 4 2, ZLKUm 1016, and Y. Yabumoto ofthe Kitakyushu Mu-
Maezato, Ishigaki-jima, 28 Oct 1962, leg. seum ofNatural History, for allowing us to
S. Kudaka; 19 5, 18 2, ZLKUm 1019, Pen- examinethe specimensundertheircareand
san-gara, Ishigaki-jima, 19 May 1963, leg. the use oflaboratory facilities.
S. Kudaka), shows that there are distinct
granules on the median part of the lower
edge ofthe epistome which are barely dis- Literature Cited
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distinctgranules on the groove between the amon De Man, Sinopotamon n. gen., Candidi-
324 PROCEEDINGSOFTHE BIOLOGICALSOCIETY OFWASHINGTON
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