Spider Crabs of the Genus Huenia De Haan, 1837 (Crustacea, Decapoda, Brachyura) from Japan, with Descriptions of Two New Species

2010·1.6 MB·English

by  Takeda, Masatsune

Bull. Natl. Mus. Nat. Sci., Ser. A, 36(2), pp. 39–48, May 22, 2010
Spider Crabs of the Genus Huenia De Haan, 1837 (Crustacea, Decapoda,
Brachyura) from Japan, with Descriptions of Two New Species
Masatsune Takeda1and Masahiro Marumura2
1Faculty of Modern Life, Teikyo Heisei University,
2–61–4 Higashi-Ikebukuro, Toshima-ku, Tokyo, 170–8445 Japan
E-mail: [email protected]
2Nanki Senior High School, 1–88 Gakuen, Tanabe-shi, Wakayama, 646–0024 Japan
E-mail: [email protected]
(Received 23 March 2010; accepted 19 April 2010)
Abstract Two new species of the genus Huenia De Haan, 1837 of the family Epialtidae (Majidae
s.l.) are described from Japan under the names of H. nagaii andH. toyoshioae. A rare and poorly
known species, H. pacificaMiers, 1879, is recorded from the Ryukyu Islands for the first time in
Japanese waters. The Hueniaspecies are sexually dimorphic and individually variable according to
the developmental stages in the shape of the carapace, but both new species are differentiated from
their eight congeners in the characteristic shape of the carapace.
Key words: Spider crabs, Huenia, Epialtidae, Majidae, new species, Ryukyu Islands, Japan.
Haan, 1837) (West Pacific from Japan to Aus-
Introduction
tralia), H. keelingensis Griffin et Tranter, 1986
In Japanese waters the genus Huenia of the (Cocos Keeling Islands in eastern Indian Ocean),
family Epialtidae (Majidae s.l.) is represented by and H. pacifica Miers, 1879 (West Pacific from
H. heraldica (De Haan, 1837) (cf. Sakai, 1938; Sulu Islands to northeast Australia, and Salas y
1976) and H. brevifrons Ward, 1941 (cf. Sakai, Gómez Island off Chile in southeast Pacific).
1976; Takeda et al., 1976). As pointed out by In the present paper, two new species are de-
Holthuis (1987), Huenia heraldica is the correct scribed under the names of Huenia nagaii sp.
name prior to H. proteus (De Haan), and it is nov. and H. toyoshioae sp. nov., and H. pacifica
well known that H. heraldica is remarkably vari- Miers, 1879 is newly recorded in the carcinologi-
able sexually, individually and developmentally cal fauna of Japan. The dried specimens in the
in the shape of the carapace with protective col- Nagai Collection of the Wakayama Prefectural
oration among seaweed. Thus there are syn- Museum of National History have been softened
onymies with confusion as in Griffin and Tranter with aqueous solution of ethylene glycol follow-
(1986) who partially revised the genus and dis- ing the technique of Thompson et al. (1966) and
tinguished eight species. The known species are preserved in 70% ethanol by the present authors.
eight as listed by Ng et al. (2008): H. australis The specimens used for this study are pre-
Griffin et Tranter, 1986 (Southern Australia), H. served in the Wakayama Prefectural Museum of
bifurcata Streets, 1870 (East Australia), H. brev- Natural History, Wakayama (WMNH) and the
ifrons Ward, 1941 (Indo-West Pacific from Japan National Museum of Nature and Science, Tokyo
to Maldive and Laccadive Islands in central Indi- (NSMT). The size of the specimens is indicated
an Ocean), H. grandidierii A. Milne Edwards, in millimeters (mm) of the breadth (cb) and
1865 (East Africa), H. halei Griffin et Tranter, length (cl) of the carapace.
1986 (Southern Australia), H. heraldica (De
40 Masatsune Takeda and Masahiro Marumura
Taxonomy slightly longer than wide; its dorsal surface re-
markably flattened, with weakly raised gastric
Family Epialtidae
and cardiac regions; gastric region indistinctly
Genus HueniaDe Haan, 1837
separated into three subequal parts, two protogas-
Huenia nagaiisp. nov. tric and one mesogastric subregions; cardiac re-
(Figs. 1–3) gion as high and large as each gastric subregion.
Lateral margin of carapace equipped with two
Material examined. Kurio, Yaku-shima I., prominent, thin lobes; anterior (hepatic) lobe dis-
south of Kyushu, 1? (cb 12.3(cid:2)cl 14.5mm), tinctly wing-like, strongly curved upward, its
holotype, WMNH-Na-Cr 0328, S. Nagai leg., margin convex, cut into some small, irregular
1988. lobes by shallow depressions, anterior margin al-
Description of holotype. Male. Carapace most transverse, inner part forming a wide gap
Fig. 1. Huenia nagaiisp. nov., holotype male (WMNH-Na-Cr0328; cb 12.3(cid:2)cl 14.5mm), dorsal (A) and ven-
tral (B) views.
Spider Crabs of the Genus Huenia from Japan 41
with supraorbital margin; posterior (branchial) carapace, ending anteriorly in a sharp preorbital
lobe triangular, directed posterolaterally, weakly tooth directed obliquely forward. Front flattened,
curved upward, with sharp tip; both margins sharply pointed at the tip, equilateral triangle in
straight, posterior margin transverse, about two dorsal view, with a median strong crest on lower
thirds as long as anterior margin. Posterior mar- surface in front of antennular fossae; heavy
gin of carapace as wide as distance between or- fringe of curled setae at lateral margins of front.
bits of both sides, developed as a thin lobe, with Chelipeds subequal, well developed, but not
rounded lateral ends. inflated, with sharp margins of merus, carpus and
Supraorbital margin weakly rimmed, not de- palm; merus trigonous, with irregular margins;
limited from anterior margin of hepatic lobe of upper margin armed with basal, median and dis-
Fig. 2. Huenia nagaiisp. nov., holotype male (WMNH-Na-Cr0328; cb 12.3(cid:2)cl 14.5mm), three different views
showing thin, wing-like hepatic outgrowths.
42 Masatsune Takeda and Masahiro Marumura
Fig. 3. Huenia nagaiisp. nov., holotype male (WMNH-Na-Cr0328; cb 12.3(cid:2)cl 14.5mm). A, right chela, outer
view; B, left ambulatory leg; C, D, left first pleopod, sternal (C) and ventral (D) views.
tal tubercles, distalmost one strongest and direct- pairs distal part of posterior margin of each
ed obliquely forward; distal margin of merus propodus provided with setae, forming sub-
armed with two tubular teeth at inner and outer chelate structure; dactylus about two thirds as
parts; outer margin of carpus adorned, with high long as propodus, with seven spines.
crest which is separated medially with a deep First pleopod slender, slightly curved outward,
gap; palm compressed, high, with a sharp upper fringed with silky hairs along outer margin, with
margin armed with median tubercle; distal end of its apex only slightly expanded at distal opening.
upper margin obtusely produced; fingers stout, Remarks. As shown in the photographs of the
toothed, meets along distal halves, with a high, holotype male (Fig. 2), the hepatic and branchial
truncated tooth from movable finger in proximal lobes are surprisingly well developed, thin and
gape between both fingers. recurved dorsally, and the ambulatory legs are
Ambulatory legs stout, strongly depressed, depressed. In most of the congeneric species, as
with sharp, thin, high anterior margins of meri, typically seen in H. heraldica (De Haan), the
carpi and propodi; meri trigonous, upper margin large outgrowths of the carapace are referred to
armed with four low, equidistant teeth, distalmost the female characters, although the holotype
one at distal end forming a tubercle with obtuse specimen of the new species is a male. The new
tip; median part of anterior margin of each car- species is described here with a sole male speci-
pus developed as a lobe, remarkably developed in men, but an interesting problem should be posed
first pair; each propodus armed with a median in future for the biological study on the sexual di-
obtuse tooth directed distally on anterior margin; morphism and mimicry, when the female will be
entire length of posterior margin forming a low found.
triangle, with a tip at median part; in first three Etymology. This species is dedicated to the
Spider Crabs of the Genus Huenia from Japan 43
late Mr. Seiji Nagai, whose collections of crabs region as large as mesogastric subregion, with
were donated to the Wakayama Prefectural Mu- obtuse tip. Lateral margins of carapace weakly
seum of Natural History, Wakayama, for scientif- concave, rimmed, not delimited from supraorbital
ic research. margins, each retreating from supraorbital spine
to epibranchial angle; branchial surface close to
Huenia pacificaMiers, 1879 epibranchial angle weakly curved dorsally; epi-
branchial angle sharp, but not spine-tipped; pos-
(Figs. 4–5)
terolateral margin of carapace behind epi-
Huenia pacifica Miers, 1879, p. 5, pl. 4 fig. 3.—Griffin branchial angle almost longitudinal in dorsal
and Tranter, 1986, pp. 73 (in key), 80, fig. 24.—Reta-
view; true posterior margin of carapace as long
mal, 2001, pp. 211–214, fig. 1.
as distance between anterior ends of both orbits.
Material examined. Off Yakata, Onna-son, Oki- Rostrum horizontal, half as long as carapace,
nawa-jima I., Ryukyu Is., 2m deep, 2?? (cl with triangular basal half and narrow distal half
12.7(cid:2)cb 5.9mm; cl 15.3(cid:2)cb 9.5mm), WMNH- compressed laterally in dorsal view, fringed with
Na-Cr 0329, 1 June 1991, S. Nagai leg.; Tokashi- curled setae; in lateral view, rostrum flattened,
ki-jima I., Kerama Group, Ryukyu Is., 1 juv.? same height throughout its length, tips subtrun-
(cb 5.5(cid:2)cl 3.0mm), NSMT-Cr 18040, May cated. Supraorbital margin not markedly raised,
2007, H. Komatsu leg. with a sharp, distal spine directed obliquely for-
Description. Males. Carapace narrow, remark- ward and weakly upward.
ably elongated, widened posteriorly; dorsal sur- Chelipeds long, stout; merus as long as palm
face flattened, with weakly raised gastric and car- and fingers combined; inner margin of merus
diac regions; surface between both orbits weakly armed with three equidistant obtuse tubercles;
concave; gastric region occupies main part of palm thick, but not inflated, with obtuse margins;
carapace, subdivided into three, viz. a pair of fingers half as long as palm, sharply toothed.
protogastric subregions arranged side by side and Ambulatory legs very slender, cylindrical;
mesogastric subregion placed medially; cardiac merus and carpus thickened distally, carpus one
Fig. 4. Huenia pacificaMiers, male (WMNH-Na-Cr0329; cb 9.5(cid:2)cl 15.3mm).
44 Masatsune Takeda and Masahiro Marumura
Fig. 5. Huenia pacificaMiers, male (WMNH-Na-Cr0329; cb 9.5(cid:2)cl 15.3mm) (A–F), juv. (NSMT-Cr 18040; cb
5.5(cid:2)cl 3.0mm) (G). A, F, G, dorsal (A, G) and lateral (F) views; B, left chela, outer view; C, left ambulatory
leg; D, dactylus, enlarged; E, left first pleopod, ventral view.
third as long as merus; propodus twice as long as margin of carapace weakly but distinctly convex
carpus, armed with an obtuse tubercle and setae outward behind orbit; posterior end of lateral
at distal one third of inner margin; dactylus slen- margin of carapace more or less lobate with ob-
der, covered with short hairs, about half as long tuse tip, different from sharp epibranchial angle
as propodus, armed with two rows of 11 spines in male. Rostrum triangular in dorsal view, much
along inner margin. shorter than mature male rostrum, corresponding
First pleopod slightly curved outward, weakly to basal half of male rostrum.
broadened at distal opening. Ambulatory legs short, stout, depressed; ante-
Juvenile male. Carapace proportionally wider rior margins of meri, carpi and propodi more or
than that of adult male; anterior part of lateral less thinly marked, convex medially; posterior
Spider Crabs of the Genus Huenia from Japan 45
margins of each merus and propodus weakly pro- cality; Australia (Queensland coast); Indonesia
duced at median part provided with cluster of (Flores Sea; Kai Is.), Philippines (Sulu Is.), Japan
longish setae; propodus provided with a bundle (Ryukyu Is., present record); Southeast Pacific
of hairs at thickened basal part of posterior mar- (Salas y Gómez I., off Chile). Based on the Sibo-
gin; dactylus only slightly shorter than propodus, ga Expedition Griffin and Tranter (1986) record-
armed with a series of more than 10 sharp spin- ed this species from the depths of 16–36 meters
ules. in Indonesian waters, with an unusual deep
Remarks. This species was hitherto recorded record of 304 meters off the Kai Islands, Indone-
only by Miers (1879), Griffin and Tranter (1986) sia.
and Retamal (2001), but was probably confused
with or misidentified as Huenia proteus (De
Huenia toyoshioaesp. nov.
Haan), which is now regarded as a synonym of
H. heraldica (De Haan). In fact, the general (Figs. 6–7)
shape of the male carapace is rather similar in the
two species, H. pacifica and H. heraldica, in the Material examined. Nagannu I., Ryukyu Is.,
narrow, elongated contour. In the present species, 53m deep, 1? (cl 13.8(cid:2)cb 8.4mm), holotype,
however, the carapace is narrower, with the epi- NSMT-Cr 16155, 22 May 2004, TV Toyoshio
branchial angle at the posterior end of the lateral Maru 04–10 cruise, M. Osawa leg.; Off Onna-
margin being directed postero-dorsally, not later- son, Okinawa-jima I., Ryukyu Is., 1/ (cl
ally as in H. heraldica. Another remarkable dif- 15.2(cid:2)cb 9.5mm), allotype, WMNH-Na-Cr
ference is the shape of the ambulatory leg, as 1266, 1 June 1991, S. Nagai leg.
rightly illustrated by Griffin and Tranter (1984); Description of holotype. Male. Carapace nar-
in Huenia pacifica the ambulatory legs are slen- row, elongated, widened posteriorly; surface
der and cylindrical, but in H. heraldica the ante- smooth, with weakly demarcated gastric and car-
rior margins of the meri, carpi and propodi are diac regions. Rostrum narrow, tapering to sharp
thin-edged, with a strong outgrowth at distal end tip in dorsal view, with weakly depressed dorsal
of each merus; in H. heraldicathe posterior mar- surface, slightly less than one third postrostral
gin of the propodus is produced to form a kind of carapace length; lower surface strongly com-
subchela together with dactylus, but in this pressed to form a sharp median keel resembling
species the dactylus is opposed to the convexity the shape of a butter knife with rounded apex;
of the posterior margin of the propodus, being rostral lateral margin and upper one third of lat-
similar in shape to a pincette. eral surface provided with curled setae facing
In this species, the female carapace is wider both directions. Preorbital spine sharp, directed
than, but not much different from, the male cara- forward, with U-shaped sinus at posterior end of
pace, while in H. heraldica, as is well known, the rostral lateral margin; supraorbital margin longi-
female carapace has two pairs of lobate lateral tudinal, truncated laterally.
outgrowths and is remarkably wider than, and Hepatic margin produced into a small lobe
quite different from, the male carapace. weakly convex laterally and dorsally in dorsal
According to Griffin and Tranter (1986), view; lateral surface truncated, with dorsal mar-
Huenia grandidierii is distinguished from H. gin thickened and curved dorsally. Branchial
heraldica and this species by the subacute (not margin produced as a thin, upcurved, wing-like
truncate) branchial lobe of the female, the lack of lobe, widely isolated from hepatic lobe; posterior
carination on the ambulatory legs, and the con- margin of lobe transverse, weakly concave.
vex (not straight) posterior margin of the cara- Right cheliped and one right ambulatory leg
pace. present, both detached. Cheliped feeble, not in-
Distribution. Indo-West Pacific (Fiji, type lo- flated; merus smooth, upper margin weakly
46 Masatsune Takeda and Masahiro Marumura
ridged, lower margin armed with three equidis- ment; sixth segment as long as fourth and fifth
tant rounded nodules; distal end of inner and segments combined, angulated at median part of
outer margins each with a more or less tubular each lateral margin; terminal segment two thirds
outgrowth; carpus comparatively large, smooth; as long as sixth segment, only weakly tapering.
palm as long as merus, smooth, with upper and First pleopod slender, very weakly curved,
lower small outgrowths at articulation with car- with oblique distal opening constricted at the
pus; fingers about half as long as palm, deeply base.
excavated inside, with several sharp teeth on its Allotype. Female. Carapace proportionally
prehensile edge. wider than male carapace, with well developed,
Ambulatory leg not slender, depressed, with upcurved hepatic lobes. Brachial lobe directed
sharp anterior margins of merus, carpus and laterally, with obliquely subtruncated margin.
propodus; both margins of merus angulated, Gastric and cardiac regions only weakly devel-
sharply in anterior margin and bluntly in posteri- oped, quite similar to those of holotype male.
or margin, with convex distal end of anterior Both chelipeds slender; merus armed with three
margin; carpus two thirds as long as merus, pro- nodules much smaller than those of holotype
duced as a convex, thin lobe for its length; propo- male; fingers meet throughout their prehensile
dus as long as merus, depressed, anterior margin edges, teeth much smaller than those of holotype
produced as a rounded lobe from median to basal male. Armatures of meri, carpi and propodi of
parts; median part of posterior margin weakly detached two ambulatory legs of left side similar
convex, with a cluster of several setae; dactylus to, but not so strong as in holotype male.
only slightly shorter than propodus, weakly ta- Remarks. This species is characteristic in the
pering, inner upper and lower margins each with shape of the male carapace having the convex he-
a row of 11 spinules. patic lobe and the wing-like branchial lobe, and
Abdomen narrow; first and second segments the main part of the female carapace is rather
constricted between coxae of fifth ambulatory rectangular and much wider than the triangular
legs of both sides, third to fifth segments taper- male carapace. These characters are diagnostic
ing, with a mound at lateral part of third seg- for this species, which is quite distinctive among
Fig. 6. Huenia toyoshioae sp. nov. A, holotype male (NSMT-Cr 16155; cl 13.8(cid:2)cb 8.4mm); allotype female
(WMNH-Na-Cr 1266; cl 15.2(cid:2)cb 9.5mm).
Spider Crabs of the Genus Huenia from Japan 47
Fig. 7. Huenia toyoshioaesp. nov., holotype male (A-H NSMT-Cr 16155; cl 13.8(cid:2)cl 8.4mm), allotype female
(I; WMNH-Na-Cr 1266; cl 15.2(cid:2)cb 9.5mm). A, B, I, carapace, dorsal (A, I) and lateral (B) views. C, ab-
domen, D, right cheliped, ventral view, E, right ambulatory leg; F, dactylus, ventral view, enlarged; G, H, left
first pleopod, sternal (G) and ventral (H) views.
the known species of the genus. The female cara- Acknowledgements
pace reminds the male carapace of Huenia
The authors’ cordial thanks are due to the au-
keelingensis Griffin et Tranter in which the he-
thority of the Wakayama Prefectural Museum of
patic lobe is more expanded than the branchial
Natural History for the permit to examine the
lobe in both sexes.
Nagai Collection donated by the widow of the
Etymology. The new species is named after
late Mr. Seiji Nagai. The authors also wish to
TV Toyoshio Maruof Hiroshima University.
48 Masatsune Takeda and Masahiro Marumura
thank Drs. Hironori Komatsu of the National tacés nouveaux appartenant à la tribu des Maiens. An-
Museum of Nature and Science, Tokyo, and nales de la Société de Entomologique de France, 4e
Série, 5: 133–147, pls. 3–5.
Masayuki Osawa of the University of Ryukyus,
Ng, P. K. L., D. Guinot and P. J. F. Davie 2008. Systema
who put the specimens for the authors’ study.
Brachyurorum: Part I. An annotated checklist of extant
The manuscript was refined by Dr. Peter K. L.
brachyuran crabs of the world. Raffles Bulletin of Zool-
Ng of the National University of Singapore, to ogy, Supplement 17: 1–286.
whom the authors are grateful for his useful com- Retamal, R. M. A. 2001. Huenia pacifica Miers, 1879
ment. first recorded of the genus and species in the southeast
Pacific. Gayana, 65: 211–214.
Sakai, T. 1938. Studies on the Crabs of Japan. 3. Brachyg-
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