Description Of A New Spider Crab, Maja Gracilipes, From The South China Sea, With Notes On The Taxonomic Validity Of M-Brevispinosis Dai, 1981

5 Pages·1999·2.2 MB·

by  H L Chen

PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
112(4):754-758. 1999.
Description of a new spider crab, Maja gracilipes, from the South
China Sea, with notes on the taxonomic validity of M, brevispinosis
Dai, 1981 (Crustacea: Decapoda: Brachyura: Majidae)
H.-L. Chen and Peter K. L. Ng
(H-LC) Institute of Oceanology, Chinese Academy of Sciences, 7 Nan-Hai Road,
Qingdao 266071, People's Republic of China; (PKLN) Department of Biological Sciences,
National University of Singapore, Kent Ridge, Singapore 119260, Republic of Singapore
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Abstract. A new species of majid crab, Maja gracilipes, is described from
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the South China Sea. It is similar to M. confragosa Griffin Tranter, 1986,
described from the Kei Islands, Indonesia, but differs in proportions of the
ambulatory legs, structure of the intercalated spine, third maxilliped, male ab-
domen, and male first pleopod. Maja brevispinosis Dai, 1981, is synonymised
with M. compressipes (Miers, 1879).
Seventeen species of spider crabs of the opod (G2). The terminology used follows
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genus Maja Lamarck, 1801, are known, of Griffin Tranter (1986). The leg length is
which 14 occur in the Indo-West Pacific the combined maximum lengths of merus,
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(Griffin Tranter 1986, Dai 1981). Dai et carpus, propodus and dactylus (measured in
al. (1986) and Dai & Yang (1991:150) re- a straight line point to point). The type
corded five species from China, M. japon- specimen is in the Institute of Oceanology,
ica Rathbun, 1932, M. spinigera de Haan, Chinese Academy of Sciences (lOCAS) in
1839, M. gibba Alcock, 1895, M. sakaii Qingdao, China.
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Takeda Miyake, 1969, and M. brevispi-
nosis Dai, 1981. A sixth species also known Maja gracilipes, new species
from China and previously placed in the ge- Figs. 1, 2
nus Leptomithrax, L. compressipes Miers, —
Material examined. Holotype, male,
1879, originally described from China, was
& carapace width 43.5 mm, carapace length
transferred to Maja by Griffin Tranter 45.4 mm, rostral length 14.4 nrni, IOCAS
(1986).
A new species of Maja is here described K33B-34, South China Sea, station 6080,
180 m, on gravel, 21 Apr 1959.
from the South China Sea. The species is —
Description ofmale holotype. Carapace
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similar to M. confragosa Griffin Tranter,
longitudinally subovate, relatively broad,
1986, but can easily be distinguished by the
width subequal to postrostral length; dorsal
structure of the intercalated spine (between surface densely covered with numerous
orbital eave and postorbital spine), third granules of various sizes and strength; mid-
maxilliped, ambulatory legs, male abdomen line weakly but distinctly elevated, with 6
and male first pleopod. The identity of M. low spines anteriorly, 2-3 pairs of low,
brevispinosis Dai, 1981, described from rounded submedian granules posteriorly.
southern China, is re-appraised, and the Rostrum with 2 long, slender spines, ca. 0.3
species is here synonymised with M. com- times postrostral length; spines gently curv-
pressipes (Miers, 1879). ing outwards; outer margin with 1-2 small,
The following abbreviations are used: submedian rounded granules; cleft between
male first pleopod (Gl), male second ple- base of rostral spines deep.
VOLUME NUMBER
112, 4 755
Orbital eave strongly expanded, anteri- bauriculiform; inner posterolateral angle tri-
orly rounded, posteriorly developed into angular, strongly produced. Ischium with
long, sharp antorbital spine; intercalated broad, shallow oblique median depression;
spine subtruncate with proximal part much margins of depression with low rounded
narrower than median part, much shorter granules. Exopod relatively broad, medially
than antorbital spine; preorbital spine ab- with low longitudinal ridge, not distinctly
sent. Eyestalks relatively narrow; cornea granular.
large, mostly ventral, ca. half length of en- Chelipeds elongate, subequal, ca. sube-
tire eye. qual postrostral carapace length. Chelae not
Basal antennal segment longitudinally swollen, surfaces smooth; fingers 0.7-0.8
subrectangular; outer lateral spine large, di- times length of palm; cutting edges un-
rected obliquely outwards, anterior margin armed, not pigmented. Carpus relatively
with 3-4 small granules; distal median short, dorsal surface with distinct sulcus;
spine short; anterolateral margin granular dorsal margin with very low crest, more
but without distinct spine or larger granule; prominent on proximal part, crest with 2
median surface with 2-3 large rounded low sharp teeth. Merus with one very low
granules. Suborbital lobe separated from submedian granule on dorsal margin, oth-
basal antennal segment by distinct fissure. erwise smooth. Basis-ischium smooth, un-
Pterygostomial region relatively smooth; armed.
margin with 5 large rounded granules. Ep- Surfaces of ambulatory legs smooth, first
istome smooth, unarmed. leg ca. subequal in length to postrostral car-
Postorbital tooth reaching slightly but apace length; second to fourth legs 1.6, 1.5-
distinctly further anteriorly than antorbital 1.6, 1.4 and 1.1-1.2 times postrostral cara-
spine, basally broad, partially excavated, pace length respectively. Merus of first leg
narrow and acutely triangular distally, tooth slender, ca. 7.5 times longer than high; dor-
directed anteriorly and obliquely outwards; sal margin with low, rounded distal tooth,
basal part with several small granules. He- otherwise unarmed, inner surfaces with
patic spine much shorter, ca. 0.3 times scattered long stiff setae. Carpus on all legs
length of postorbital tooth; base and area with median sulcus, inner surface (espe-
posterior to it covered with numerous large cially of first leg) with numerous long, stiff
rounded granules. setae; propodus laterally flattened, slender.
Branchial region with 4 low but distinct Second to fourth legs with merus ca. 7.5,
spines (or large sharp granules), 3 clearly 7.0, 5.8 times longer than high respectively;
marginal and 1 submarginal in position; dorsal margin of merus smooth, without
dorsal surface with 1 large, rounded granule distinct distal tooth; inner surfaces of merus
which is smaller than marginal ones, adja- and carpus with scattered long, stiff setae.
cent to median cardiac spine. Mesogastric Dactylus of all legs gently curved, un-
region with 4 low, large, rounded median armed, ventral margin with numerous short,
granules, not spiniform; urogastric region stiff setae.
with 1 low, large median granule. Cardiac Thoracic stemites 1 and 2 fused, demar-
region with 1 median and 1 anterior low, cated by granular ridge; stemites 2-4 com-
large, rounded median granules; posterior pletely fused, without trace of sutures, sur-
surface with 2 sharper granules. Anterior face smooth, lateral margins cristate; sur-
surface of intestinal region with 2 large sub- faces of stemites 5-8 covered with numer-
median granules; posterior surface with 2 ous small granules. Telson semicircular;
small sharp spines. segments 4-6 longitudinally rectangular,
Merus of third maxilliped with postero- lateral margins of each segment gently con-
median margin raised, not distinctly gran- cave; segment 3 trapezoidal, anterolateral
ulated, anteroextemal angle rounded, su- margin gently concave, posterolateral mar-
756 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
Fig. 1. Maja gracilipes, new species. Holotype male, carapace width 43.5 mm, lOCAS K33B-34. a, left
frontal part of carapace (dorsal view); b, left frontal part of carapace (ventral view); c, right third maxilliped; d,
left first ambulatory leg; e, left second ambulatory leg; f, right third ambulatory leg; g, right fourth ambulatory
leg.
VOLUME 112, NUMBER 4 757
Fig. 2. Maja gracilipes, new species. Holotype male, carapace width 43.5 mm, lOCAS K33B-34. a, b, left
Gl; c, d, distal part of Gl; e, left G2; f, abdomen (schematic outline only).
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gin rounded; surfaces with scattered gran- Remarks. Maja gracilipes, new species,
ules. is closest to M. confragosa, especially with
Gl relatively long; basal part dilated; regards to the general carapace morpholo-
median part almost straight from ventral gy, presence of a large spine on the lateral
view but gently curving when viewed in margin of the basal antennal segment, and
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situ; distal part with one perpendicular general structure of the Gl (Griffin Tran-
tooth-like projection, dorsal margin with ter 1996:210). Maja gracilipes can easily be
numerous stiff setae. Male second pleopod separated from M. confragosa by the pres-
very short. — ence of a subtruncate intercalated tooth
Etymology. The name is derived from with the median part broader than the prox-
the Latin gracilis (for slender) and pes (for imal part (Fig. la) (against acutely trian-
leg), alluding to the relatively long ambu- gular with the median part distinctly nar-
latory legs of the species. Used as a noun rower than the proximal part); anteroexter-
in apposition. nal angle of the third maxilliped ischium is
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758 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
angular (Fig. Ic) (against rounded); propor- author was supported by a research grant
tionately longer ambulatory meri and pro- from the National University of Singapore.
podi (Figs. Id-g); relatively broader male This is contribution number 3598 from the
abdomen, notably segment 3 (Fig. 2f); and lOCAS.
the distal part of the Gl (beyond the lateral
subdistal projection) is proportionately lon- Literature Cited
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ger (Figs. 2a-d) (cf. Griffin Tranter 1986: Alcock, A. 1895. Materials for a carcinological fauna
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214, 215, Figs. 72a-c, 73a, pi. 16). of India, 1. The Brachyura Oxyrhyncha. Jour-
Maja confragosa was originally de- nal of the Asiatic Society of Bengal 64:157-
scribed by Griffin & Tranter (1986) from 291, pis. 3-5.
Dai, A.-Y. 1981. Two new species ofChinese Majidae
only one male (carapace length 39.0 mm) —
(Crustacea: Brachyura). Acta Zootaxonomica
from the Kei Islands in Indonesia, and con- Sinica 6(l):36-38, pi. 1.
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sidering its slender chelipeds, appears to be , S. Yang. 1991. Crabs of the China Seas.
a subadult specimen. Its Gl, however, is China Ocean Press (Beijing). 682 pp, figs. 1-
fully developed. The male specimen of M. 295, pis. 1-Y74. &
gracilipes is somewhat larger (carapace t,he China, SeaSso.ngC,hinaG.OCcheeann, P1r9e8s6s., CBreaibjsingo.f
length 45.4 mm) and the chelipeds are al- 17+642 pp., pis. 1-74. [In Chinese]
ready relatively enlarged. The differences Griffin, D. J. G., & H. A. Tranter. 1986. The Decapoda
observed between the male specimens, es- Brachyura—of the Siboga Expedition. Part VHI.
Majidae. Siboga-Expeditie 39C4:1-335, 22
pecially in the proportions of the legs, can-
pis.
not be accounted for by size-associated var- Haan, W. De. 1833-1849. Crustacea. In: P E Siebold,
iation. Fauna Japonica sive Descriptio Animalium,
On another matter, M. brevispinosis Dai, quae in Itinere per Japoniam, Jussu et Auspiciis
1981, bears a striking resemblance to M. Superiorum, Qui Sununum in India Batava Im-
perium Tenent, Suscepto, Annis 1823-1830
compressipes (Miers, 1879) in its carapace
Collegit, Notis, Observationibus et Adumbra-
features, short ambulatory legs and posses- tionibus Illustravit, (Crustacea): i-xvii + i-xxxi
sion of an ambulatory carpus which is very + i-ix-xvi + 1-243, pis. A-J, L-Q, 1-55, circ.
broad and triangular in shape. Interestingly, tabl. 2. Lugduni-Batavorum.
M. compressipes is known only from the Lamarck, J. B. P. A. 1801. Systeme des animaux sans
holotype female from Canton (= Guang- vertebres, ou tableau general des classes, des
ordres et des genres de ces animaux' presentant
dong), China, while M. brevispinosis was
leurs caracteres essentiels et leur distribution,
described from two males and a female d'apres la consideration de leurs rapports natu-
from the same area. From the descriptions rels et de leur organisation, et suivant
and figures of the holotype female of M. rarrangement etabli dans les galeries du Mu-
& seum d'Hist. Naturelle, parmi leurs depouilles
compressipes (cf. Griffin Tranter 1986:
conservees; precede du discours d'ouverture du
211, pi. 16) and types of M. brevis&pinosis cours de zoologie, donne dans le Museum na-
(see Dai 1981:37, figs. 1:6-10; Dai Yang tional d'Histoire namrelle I'an 8 de la Repub-
1991:151, pi. 18(2), figs. 77(1-4)), we can iique. Paris, viii4-432 pp.
find no reason to separate the two species. Miers, E. J. 1879. On a collection of Crustacea made
As such, Maja brevispinosis Dai, 1981, is by Capt. H. C. St. John, R. N. in the K—orean
and Japanese seas, 1. Podophthalmia. Pro-
here synonymised with M. compressipes
ceedings of the Zoological Society of London
(Miers, 1879). 1879:18-61, pis. 1-3.
Rathbun, M. J. 1932. Preliminary—descriptions ofnew
Acknowledgements species of Japanese crabs. Proceedings of the
Biological Society of Washington 45:29-38.
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The senior author's work in Singapore Takeda, M., S. Miyake. 1969. Crabs from the East
China Sea. 3. Brachygnatha Oxyrhyncha.
was partially supported by a travel grant Journal of the Faculty of Agriculture, Kyushu
from the Raffles Museum, while the junior University 15:469-522.