Rare Crabs (Crustacea, Decapoda, Brachyura) from Okinawa Island, with Description of a New Species of the Family Leucosiidae

2009·4.1 MB·English

by  Komatsu, H

Bull. Natl. Mus. Nat. Sci., Ser. A, 35(2), pp. 125–136, June 22, 2009
Rare Crabs (Crustacea, Decapoda, Brachyura) from Okinawa Island,
with Description of a New Species of the Family Leucosiidae
Hironori Komatsu1and Masatsune Takeda2
1Department of Zoology, National Museum of Nature and Science,
3–23–1 Hyakunincho, Shinjuku-ku, Tokyo, 169–0073 Japan
E-mail: [email protected]
2Faculty of Modern Life, Teikyo Heisei University,
2–51–4 Higashi-Ikebukuro, Toshima-ku, Tokyo, 170–8445 Japan
E-mail: [email protected]
Abstract A small collection of brachyuran crabs made by night SCUBA at Okinawa Island, the
Ryukyu Islands, is examined. A new species of leucosiid crab, Heteronucia fujitai, is described
and illustrated based on single female specimen. Heteronucia fujitaiis similar to H. laminata, but
can be distinguished from H. laminata by the broader carapace, the fourth ambulatory leg being
without laminar margin, and the concealed first segment of the female abdomen. All the species
examined are listed, and some rare species of the families Aethridae, Leucosiidae, and Parthenopi-
dae are noted with supplementary descriptions and remarks.
Key words:Crustacea, Decapoda, Brachyura, Okinawa, Ryukyu Islands, Heteronucia fujitai, new
species.
Introduction Taxonomy
Okinawa Island in the Ryukyu Islands is locat- Family Dromiidae
ed in the southwestern most part of Japan. It is Lewindromia unidentata(Rüppell, 1830)
strongly influenced by the main stream of the
[Japanese name: Kinuge-kamuri]
warm Kuroshio Current and is known to have
(Fig. 1A)
very rich fauna. Numerous surveys had already
been carried out around this island, however, the
Material examined. Cape Maeda, Onna, Oki-
fauna still remains to be completely elucidated.
nawa I., 7.8m deep; 1? (cl 21.4(cid:1)cb 19.7),
A small collection of brachyuran crabs made
NSMT-Cr 20822; 16 August 1998.
by night SCUBA at the littoral area of Okinawa
Distribution. Widely distributed in Indo-Pacif-
Island was provided us by Dr. Yoshihisa Fujita of
ic (McLay, 1993).
the University of the Ryukyus. Since most of
crabs inhabiting shallow water are more active in
the night than in the daytime, night SCUBA is a Family Homolidae
useful method for collecting shallow-water crabs. Latreillopsis laciniataSakai, 1936
Measurements, given in millimeters (mm), are [Japanese name: Edatoge-mizuhiki-gani]
of the greatest carapace length (cl) (including the
(Fig. 1B)
posterior lobe and excluding the rostral spine)
Material examined. Cape Maeda, Onna, Oki-
and breadth (cb), respectively. All the specimens
nawa I., 12.7m deep; 1/ (cl 11.6 in median
examined are deposited in the National Museum
line(cid:1)cb 8.3 between branchial regions of both
of Nature and Science (NSMT).
sides), NSMT-Cr 20823; 5 May 1998.
Distribution. Known only from Japan (Guinot
126 Hironori Komatsu and Masatsune Takeda
and Richer de Forges, 1995). ent channel without tooth on mesial margin; an-
terior margin with V-shaped notch on lateral cor-
ner.
Family Calappidae
Mandible (Fig. 3A–B) well calcified; cutting
Calappa gallus(Herbst, 1803)
edge triangular in outline, pointed medially; en-
[Japanese name: Kobu-karappa] dopod palp 3-segmented, first segment very
(Fig. 1C) short, densely fringed with stout setae on termi-
nal segment. Maxillule (Fig. 3C): coxal endite
Material examined. Cape Maeda, Onna, Oki-
nawa I., 8 m deep; 1/ (cl 19.4(cid:1)cb 24.1), NSMT- rod-like, directed mesially, fringed with short
setae, terminal setae stout; basial endite triangu-
Cr 20824; 14 May 1998.
lar, fringed with stout and thin setae on mesial
Distribution. Widely distributed in Indo-West
margin, with 1 plumose seta on lateral margin;
Pacific (Galil, 1997).
endopod stilliform, with some plumose setae on
proximal part of lateral margin. Maxilla (Fig.
Family Leucosiidae
3D): coxal endite roundly bilobed; basial endite
Heteronucia fujitaisp. nov. elongate triangular, with some terminal setae; en-
[New Japanese name: Manju-ibo-tsubu-kobushi] dopod tongue-shaped, with 1 seta on apex; exo-
(Figs. 1D, 2–3, 4A–B) pod (scaphognathite) longitudinally expanded
into oval structure, entirely fringed with short,
Nuciasp.: Minemizu, 2000, p. 201 (color photograph).
plumose setae. First maxilliped (Fig. 3E): coxal
Material examined. Mizugama, Kadena, Oki- endite rounded, with dense, weakly plumose
nawa I., 6 m deep; 1 ovig./ (cl 11.5(cid:1)cb 12.9), setae; basial endite subtriangular, densely fringed
holotype, NSMT-Cr 20825; 7 Aug. 1998. with moderately long, plumose setae along
Description of holotype. Carapace (Fig. 1D, mesial margin; endopod longitudinally expanded,
4A) subglobular, 1.1 times broader than long; rounded at apex, fitting in efferent channel,
dorsal surface evenly covered with small rounded fringed with very short setae on apex; exopod
granules, sparsely studded with small, subconical longitudinally filiform, with some plumose setae
tubercles and very short, plumose setae; regions on apex, bearing flagellum with some terminal
ill-defined, with very shallow, H-shaped groove setae. Second maxilliped (Fig. 3F): ischium and
between cardiac and intestinal regions. Frontal merus fringed with long plumose setae along
region weakly produced, concave medially. mesial margin; propodus with dense setae along
Pterygostomian margin weakly convex outwards. lateral margin and on disto-lateral part; dactylus
Branchial margin roundly convex, with 2 small, armed with stout setae around tip; exopod taper-
triangular tubercles on posterior half, tubercles ing distally, with some plumose setae on apex,
weakly hooked and covered with cluster of gran- bearing flagellum with some terminal setae; ex-
ules. Posterior margin with 2 small, triangular tu- odite rounded.
bercles on both sides, tubercles covered with Third maxilliped (Fig. 3G–H) covered with
cluster of granules. round granules of various sizes; basis fused with
Ocular peduncle (Fig. 2A) very short. Orbit ischium but with suture on both surfaces; ischi-
with 2 short, straight fissures on dorsal roof, with um subsquamate; merus moderately bent dorsally
V-shaped notch on infraorbital margin; orbital in situ, about 0.76 times as long as ischium along
hiatus open. Antennule obliquely folded into mesial margin; propodus and dactylus with dis-
fossa; basal segment occupying ventral 0.4 of tally denticulate, stout setae along inner margin;
fossa, covered with very short setae. Antenna: exopod subsquamate, rounded at tip, fringed with
basal segment transversely ovate; second seg- short plumose setae along lateral margin; internal
ment subsquamate, constricted anteriorly. Affer- exopodal ridge prominent, with dense setae along
Rare Crabs from Okinawa Island 127
Fig. 1. A, Lewindromia unidentata(Rüppell, 1830), male (cl 21.4(cid:1)cb 19.7), NSMT-Cr 20822; B, Latreillopsis
laciniataSakai, 1936, female (cl 11.6(cid:1)cb 8.3), NSMT-Cr 20823; C, Calappa gallus(Herbst, 1803), female
(cl 19.4(cid:1)cb 24.1), NSMT-Cr 20824; D, Heteronucia fujitaisp. nov., holotype ovig. female (cl 11.5(cid:1)cb 12.9
mm), NSMT-Cr 20825; E, Nucia speciosaDana, 1852, female (cl 12.2(cid:1)cb 13.7), NSMT-Cr 20826; F, Raylil-
ia uenoi(Takeda, 1995), female (cl 12.0(cid:1)cb 13.1), NSMT-Cr 20827. (Photo: Y. Fujita)
ridge; epipod reduced, translucent on distal half; and carpus subcylindrical, covered with large,
podobranch absent. pearly granules; palm convex dorsally, slightly
Cheliped (Fig. 2B) moderate, 1.3 times as long constricted distally, covered with pearly granules,
as carapace, sparsely furnished with very short, granules smaller than those of merus and carpus;
plumose setae; coxal condyle subcircular; merus fingers weak, about 0.8 times as long as palm,
128 Hironori Komatsu and Masatsune Takeda
Fig. 2. Heteronucia fujitai sp. nov., holotype ovig. female (cl 11.5(cid:1)cb 12.9), NSMT-Cr 20825. A, frontal re-
gion, ventral view; B, left chela, dorsal view; C, right first ambulatory leg, posterior view; D, abdomen, ven-
tral view. Scales: 1mm.
with gap between cutting edges along proximal scopic granules.
0.8 when closed, with thin, fine teeth along both Thoracic sternites covered with rounded gran-
cutting edges, teeth continuous in distal 0.7. ules of various sizes; first to fourth sternites
Ambulatory legs (Fig. 2C) moderate length, fused; fourth to eighth sternites with medially in-
similar in shape, gradually decreasing in length terrupted sutures between sternites; abdominal
from first to fourth, covered with small, rounded cavity reaching to buccal cavity.
granules except dactyli, sparsely furnished with Abdomen (Fig. 2D) covered with rounded
short plumose setae; coxal condyles rounded; granules of various sizes; first segment complete-
meri and carpi subcylindrical; propodi weakly ly concealed beneath carapace; second and third
compressed; dactyli subconical, with smooth segments short, transversely subrectangular;
dactylo-propodal locks on proximal ends of dor- main fused section composed of fourth to sixth
sal surfaces, covered with inconspicuous, micro- segments, ovate, moderately convex ventrally;
Rare Crabs from Okinawa Island 129
Fig. 3. Right mouth parts of Heteronucia fujitai sp. nov., holotype ovig. female (cl 11.5(cid:1)cb 12.9), NSMT-Cr
20825. A, mandible, external view; B, same, internal view; C, maxillule, external view; D, maxilla, external
view; E, first maxilliped, external view; F, second maxilliped, external view; G, third maxilliped, external
view; H, same, internal view. Scale: 1mm.
130 Hironori Komatsu and Masatsune Takeda
Fig. 4. A–B, Heteronucia fujitai sp. nov., holotype ovig. female (cl 11.5(cid:1)cb 12.9), NSMT-Cr 20825; C–D,
Pseudolambrus longispinosus(Flipse, 1930), female (cl 16.9(cid:1)cb 18.2), NSMT-Cr 20833.
telson tongue-shaped, fringed with very short to be very short in H. laminata). This species is
setae. also photographed as Nucia sp. by Minemizu
Color. Dorsal surfaces of carapace, chelipeds (2000) from Miyako Island, the Ryukyu Islands,
and ambulatory legs cream, symmetrically at the depth of 6m. Although the specimen was
speckled with red punctae. not collected, the photograph clearly shows that
Etymology. This species was named after Dr. his species belongs to the present new species.
Yoshihisa Fujita of the University of the Ryukyus Distribution. Known only from Okinawa Is-
who kindly provided us the specimens for study. land and Miyako Island, the Ryukyu Islands, oc-
Remarks. Heteronucia fujitaisp. nov. is similar curring at depth of 6m.
to H. laminata (Doflein, 1904) in the grobular
carapace with only divided intestinal region, but
Nucia speciosaDana, 1852
can be distinguished from H. laminataby that (1)
[Japanese name: Ibo-tsubu-kobushi]
the carapace is broader than long (vs. longer than
(Fig. 1E)
broad in H. laminata); (2) the ambulatory legs
have no laminar margin (vs. the merus, carpus Material examined. Cape Maeda, Onna, Oki-
and propodus of the fourth ambulatory leg have nawa I., 2m deep; 1 / (cl 12.2(cid:1)cb 13.7), NSMT-
laminar inner margins in H. laminata); (3) the Cr 20826; 19 May 1998.
first segment of the female abdomen is complete- Distribution. Whole Indo-West Pacific (Chen
ly concealed beneath the carapace (vs. appeared and Sun 2002).
Rare Crabs from Okinawa Island 131
Raylilia uenoi(Takeda, 1995) Urnalana insularis: Galil, 2005, p. 24, figs. 2D, 7A.
[Japanese name: Ueno-kobushi]
Material examined. Mizugama, Kadena, Oki-
(Fig. 1F) nawa I., 3m deep; 1 young / (cl 7.7(cid:1)cb 8.0),
Arcania uenoiTakeda, 1995, p. 151, figs. 1–2. NSMT-Cr 20828; 9 October 1996.
Raylilia uenoi: Galil, 2001, p. 73, figs. 7–8. Remarks. Galil (2005) transferred this species
to the new genus Urnalana and compared with
Material examined. Cape Maeda, Onna, Oki-
the closely related U. elata (A. Milne Edwards)
nawa I., 8m deep; 1/ (cl 12.0(cid:1)cb 13.1), NSMT-
to which Leucosia sagamiensis Sakai and L.
Cr 20827; 4 August 2004.
bikiniensis Sakai were synonymized. The speci-
Remarks. The specimen at hand is a female of
men examined is a young female, so that it is im-
good size and generally agrees well with the pre-
possible to compare the first male pleopod, but
vious descriptions except for the mesobranchial
the contour of the carapace is seemingly differ-
tubercle shorter than the male specimens. This
ent, with the longer posterolateral margin of the
species was originally referred to the genus Arca-
carapace in U. elata. Another congener, U. elatu-
nia, and later included in the genus Raylilia
laGalil is also close to this species in the general
newly established by Galil (2001) together with
shape of the carapace, but mentioned that the an-
Arcania gracilipes Bell, Randallia mirabilis
terolateral margin of the carapace is angled and
Zarenkov and Raylilia coniculifera Galil. Ac-
the third maxilliped coxa in female has a conical
cording to Galil (2001), Raylilia is distinguished
tubercle. In the present female the anterolateral
from Arcaniaby having the basal antennular seg-
margin of the carapace is not always nearly
ment entirely sealing the antennular fossa, the
oblique, but also more or less angled, but the
anterior margin of the efferent branchial channel
third maxilliped coxa is quite smooth.
medially fissured and separated from the orbital
Distribution. Japan, Mariana Is., Fiji, New
margin by a deep groove, the posterior margin of
Caledonia, Loyalty Is., Chesterfield Is., 1–200m
the carapace tridenticulate, the third to sixth seg-
deep (Galil, 2005).
ments of the male abdomen fused and bearing a
preapical tubercle, and the first male pleopod dis-
tally expanded lamellate. Urnalana purarensis(Ovaere, 1987)
This species differs from the congeners most [Japanese name: Kume-jima-kobushi]
remarkably in having a strong mesobranchial tu- (Fig. 5B)
bercle directed obliquely backward and longer
Leucosia purarensis Ovaere, 1987, p. 192, figs. 2b, 6a;
than the intestinal tubercle. The first male pleo-
Marumura and Kosaka, 2003, p. 29, fig. 13.
pod is characteristic in having the widened petal-
Urnalana purarensis: Galil, 2005, p. 30, figs. 3B, 8B.
shaped tip evenly denticulate along the margin.
Material examined. Cape Maeda, Onna, Oki-
Distribution. This species was originally re-
nawa I., 3m deep; 1? (cl 7.3(cid:1)cb 7.6), NSMT-Cr
ported from Ie-jima Island in the Ryukyu Islands,
20829; 4 May 1998.
35m deep, and later from the Sulu Archipelago,
Remarks. This is the second record of this
Java, Chesterfield Island, New Caledonia and
species from Japanese waters. Marumura and
Madagascar, 30–65m deep.
Kosaka (2003) listed this species from Kume Is-
land, Kerama Group, the Rhyukyu Islands, 15–20
Urnalana insularis(Takeda and Kurata, 1976)
m deep, with a color photograph. The female
[Japanese name: Ogasawara-kobushi] specimen was examined by the junior author at
(Fig. 5A) the Wakayama Prefectural Museum of Natural
History. These specimens agree well with the
Leucosia insularisTakeda and Kurata 1976, p. 21, figs. 1,
3a, pl. 1 fig. 1; Ovaere, 1987, p. 185. original description (Ovaere, 1987) and the sub-
132 Hironori Komatsu and Masatsune Takeda
Fig. 5. A, Urnalana insularis(Takeda and Kurata, 1976), young female (cl 7.7(cid:1)cb 8.0), NSMT-Cr 20828; B,
Urnalana purarensis(Ovaere, 1987), male (cl 7.3(cid:1)cb 7.6), NSMT-Cr 20829; C, Drachiella caelataTakeda
and Tachikawa, 1995, female (cl 14.9(cid:1)cb 20.0), NSMT-Cr 20830; D, Furtipodia petrosa(Klunzinger, 1906),
male (cl 15.9(cid:1)cb 23.9), NSMT-Cr 20831; E, Pseudolambrus longispinosus (Flipse, 1930), female (cl
16.9(cid:1)cb 18.2), NSMT-Cr 20833; F, Crossotonotus spinipes (De Man, 1888), female (cl 32.3(cid:1)cb 37.3),
NSMT-Cr 20834. (Photo: Y. Fujita)
sequent description by Galil (2005). Family Aethridae
Distribution. Japan, Taiwan, Papua New Drachiella caelataTakeda and Tachikawa, 1995
Guinea (type locality), Guam, Tahiti, Tuamotu
[Japanese name: Ukibori-mizo-kobushi]
Archipelago, occurring at the depths of 0–12m
(Figs. 5C, 6)
(Galil, 2005; present study).
Drachiella caelata Takeda and Tachikawa, 1995, p. 212,
Rare Crabs from Okinawa Island 133
fig. 1. minal segment. Maxillule: coxal endite rod-like,
directed mesially, densely fringed with stout and
Material examined. Mizugama, Kadena, Oki-
thin setae on lateral margin; basial endite triangu-
nawa I., 8.2m deep; 1/ (cl 14.9(cid:1)cb 20.0),
lar, fringed with stout and thin setae on mesial
NSMT-Cr 20830; 7 August 1998.
margin, with some weakly plumose setae on lat-
Supplementary description. Mandible well cal-
eral margin; endopod stilliform, unsegmented,
cified; cutting edge triangular in outline, pointed
with some plumose setae on proximal part of lat-
medially; endopod palp 3-segmented, first seg-
eral margin. Maxilla: coxal endite roundly
ment very short, fringed with short setae on ter-
Fig. 6. Drachiella caelata Takeda and Tachikawa, 1995, female (cl 14.9(cid:1)cb 20.0), NSMT-Cr 20830. A, right
third maxilliped, external view; B, same, internal view; C, left chela, dorsal view; D, right first ambulatory
leg, posterior view; E, abdomen, ventral view. Scales: 1 mm.
134 Hironori Komatsu and Masatsune Takeda
bilobed; basial endite narrow, elongate triangular, carpi, and propodi subcylindrical, with acute
with some terminal setae; endopod tongue- granules on outer surfaces; dactyli subconical,
shaped; exopod (scaphognathite) longitudinally without dactylo-propodal locks.
expanded into oval structure, entirely fringed Abdomen (Fig. 6E) longitudinally ovoid; all
with short, plumose setae. First maxilliped: coxal segments divided from each other, but 2nd to 6th
endite rounded, with dense, weakly plumose segments are fused together and immovable; 1st
setae; basial endite subtriangular, densely fringed segment very short, transversely linear; 2nd to
with moderately long, plumose setae; endopod 6th segments short, almost same length, trans-
longitudinally expanded, rounded at apex, fitting versely subrectangular, covered with pearly gran-
in efferent channel, fringed with short setae ules of various sizes; telson subtriangular, tip
along margin of distal half, carinate on upper sur- tongue-shaped.
face; exopod longitudinally filiform, bearing fla- Remarks. This is the second record of this
gellum with some terminal setae. Second maxil- species since the original description from the
liped fringed with long plumose setae along Ogasawara Islands. The type specimens are only
mesial margin of ischium and merus and lateral empty shell without all appendages and ab-
margin of merus; propodus and dactylus densely domen, therefore this is the first live specimen of
fringed with long setae, setae around tip of this species. The present specimen agrees well
dactylus stout; exopod narrow, tapering distally, with the original description in the characteristic
fringed with short plumose setae on proximal areolation of the upper surface of the carapace.
half of lateral margin, bearing flagellum with Supplementary description of the mouthparts,
some terminal setae; exodite rounded. pereiopods, and female abdomen is provided in
Third maxilliped (Fig. 6A–B) covered with this paper.
coarse, rounded granules of various sizes; basis Recently Ng et al. (2008) removed the genus
fused with ischium but with suture on internal Drachiella from the family Leucosiidae to the
surface; ischium subsquamate; merus moderately family Aethridae. But the shape of the mouth-
bent dorsally in situ, about 0.60 times as long as parts and the afferent channel suggests this genus
ischium along mesial margin; dactylus with dis- belongs to the family Leucosiidae. To clarify the
tally denticulate, stout setae along inner margin; taxonomic position of Drachiella, further phylo-
exopod subsquamate, rounded at tip, fringed with genetic analysis is needed.
short setae along lateral margin; internal exopo- Distribution. Known only from Ogasawara Is.
dal ridge prominent, with short setae along ridge; and Ryukyu Is., Japan, at the depths of 6–8m.
epipod reduced, translucent on distal half;
podobranch absent.
Family Parthenopidae
Cheliped (Fig. 6C) moderate, 1.1 times as long
Furtipodia petrosa(Klunzinger, 1906)
as carapace, covered with rounded granules of
various sizes; coxal condyle rounded; merus and [New Japanese name: Gareba-hishi-gani]
carpus subcylindrical; palm broad, convex dor- (Fig. 5D)
sally; movable finger subconical, about as long as
Heterocrypta petrosa Klunzinger, 1906, p. 53, pl. 2(9);
palm, without gap between cutting edges when Lenz, 1910: 543.
closed; immovable finger blade-like, about twice Furtipodia petrosa: Tan and Ng, 2003, p. 403, figs. 4b,
as broad as movable finger; both cutting edges 5c–d.
Daldorfia horrida: Hoover, 1998, p. 271, photo (b). [Not
with triangular teeth of various sizes.
Cancer horridusLinnaeus, 1758]
Ambulatory legs (Fig. 6D) short, similar in
shape, gradually decreasing in length from 1st to Material examined. Cape Maeda, Onna, Oki-
4th, coarsely covered with granules of various nawa I., 9m deep; 1? (cl 15.9(cid:1)cb 23.9), NSMT-
sizes and shapes; coxal condyles rounded; meri, Cr 20831; 6 August 1998.