Ethusa crassipodia, Castro, 2005

Castro, Peter, 2005, Crabs of the subfamily Ethusinae Guinot, 1977 (Crustacea, Decapoda, Brachyura, Dorippidae) of the Indo-West Pacific region, Zoosystema 27 (3), pp. 499-600 : 516-518

Ethusa crassipodia n. sp.

( Fig. 6 )

TYPE MATERIAL. — Holotype: cl 11. 0 mm, cw 10.7 mm, SALOMON 1, stn CP 1992 ( MNHN- B 28736); paratype: cl 9.3 mm, cw 8.9 mm, SALOMON 1, stn CP 1783 ( MNHN-B 28701 ).

TYPE LOCALITY. — Solomon Islands, east of Malaita island, 08°32.8’S, 160°41.7’E, 399- 700 m.

MATERIAL EXAMINED. — Solomon Islands. SALOMON 1, stn CP 1783, 08°32.8’S, 160°41.7’E, 399-700 m, 29.IX.2001, 1 paratype ( MNHN-B 28701). — Stn CP 1792, 09°15.4’S, 160°08.9’E, 477- 505 m, 30. IX.2001, 1 holotype ( MNHN-B 28736).

ETYMOLOGY. — From crassus (Latin for thick, stout) and pedis (Latin for feet) in reference to the characteristically thick, stout P2-P5.

DISTRIBUTION. — Known only from the Solomon Is. Depth: 399-700 m ( Fig. 34 ).

SIZE. — Maximum size: cl 11.0 mm, cw 10.7 mm (MNHN-B 28736), unknown.

DESCRIPTION

Carapace of males (females unknown) slightly longer than broad ( Fig. 6A ); hepatic region granular, rest smooth; short hairs along anterior bor- der, long along anterolateral borders. Urogastric, cardiac regions elevated, bordered by conspicuous grooves; cervical, branchial grooves indistinct; two distinct, round depressions on each side of distal border of protogastric region, one on each side of urogastric region. Branchial regions slightly inflated along sides.

Anterior border of carapace ( Fig. 6A ) with slen- der to broad, triangular, distally acute, outwardly directed, outer orbital teeth, longer than but not reaching frontal teeth. Frontal teeth slender. Orbital sinuses broad, V-shaped, small, short vertical fissure at dorsal lower margin of each sinus, nearly symmetrical (inner and outer margins each with proximal swelling); lateral frontal sinuses U-shaped; median frontal sinus V-shaped, wider than lateral frontal sinuses but narrower than orbital sinuses.

Anterior border of endostome ( Fig. 6B ), at level of antennular fossae of basal antennular articles.

Male chelipeds (P1) (female unknown) smooth, equal; propodi slender, slightly longer than fingers; fingers without teeth or cutting edges.

P2 ( Fig. 6A ), P3 relatively short, very thick; meri with very small granules; length of P2 meri 0.7 times cl, P2 meri 4.7 times longer than broad. P4, P5 thick, smooth; P5 dactyli thick, curved.

Male abdomen (female unknown) with four somites (3-5 fused, basal half slightly swollen), triangular telson. Somite 1 trapezoidal, maximum length 3.3 times as broad, somite 6 square. G1 ( Fig. 6C ) slender, moderately sinuous; each distal end pointed with few very short spines on tip and numerous minute spines along ventral margin, small lip at distal 1/3 of ventral margin; G2 ( Fig. 6D ) thin, each distal part narrower; curved, pointed tip.

REMARKS

Ethusa crassipodia n. sp. is being described from only two specimens from the Solomon Is, both males. Nevertheless, its diagnostic characters are not found in any of the described species of Ethusa . It shares with Ethusa andamanica Alcock, 1894 , relatively short and thick P2-P5 but the two species differ in the shape of their respective carapaces. In E. andamanica the sides of the carapace are nearly straight and the outer orbital teeth are straight ( Alcock & Anderson 1895: pl. 14, fig. 8). The P2-P5 are also relatively short and thick in Ethusa orientalis Miers, 1886 , but its carapace is very granular and with nearly straight sides ( Fig. 14 ; Miers 1886: pl. 28, fig. 1).

Other species have relatively short and thick P2- P5 but they clearly differ in other characters from E. crassipodia n. sp. E. machaera n. sp. from Madagascar differs from E. crassipodia n. sp. in the morphology of the anterior border of its carapace ( Fig. 13A ). E. sexdentata ( Stimpson, 1858) has relatively longer and more slender P2-P5 ( Sakai 1976: pl. 23, fig. 1; 1965: pl. 11, fig. 2; Miyake 1983: pl. 6, fig. 5) than E. crassipodia n. sp., and has broadly triangular outer orbital teeth ( Sakai 1937: fig. 1a; 1976: fig. 26a; Chen 1993: fig. 8a). There are similarities between their G1, however, although they are slightly more slender in E. crassipodia n. sp. than in E. sexdentata . E. abbreviata n. sp. has a much shorter buccal funnel ( Fig. 2B ) than that of E. crassipodia n. sp., more slender outer orbital teeth, broad and U-shaped orbital sinuses ( Fig. 2A ), and broad-tipped G1 ( Fig. 2C ).

Figures

FIG. 6. — Ethusa crassipodia n. sp., paratype cl 9.3 mm, cw 8.9 mm, Solomon Islands, E of Malaita, SALOMON 1, stn CP 1783, 399-700 m (MNHN-B 28701); A, dorsal surface of carapace and P2; B, ventral view of anterior portion of body; C, left G2, ventral view; D, left G1, dorsal (left) and ventral (right) views. Scale bars: A, 5 mm; B, 2 mm; C, D, 1 mm.

FIG. 34. — Bathymetric distribution of Indo-West Pacific ethusine crabs.

FIG. 14. — Ethusa orientalis Miers, 1886, lectotype cl 15.7 mm, cw 15.1 mm, Fiji, E of Kadavu, Challenger, stn 173A, 567 m (BMNH 84-44); A, dorsal surface of carapace; B, left G1, ventral (left) and dorsal (right) views; C, right G2, dorsal view. Scale bars: A, 3 mm; B, C, 2 mm.

FIG. 13. — Ethusa machaera n. sp., holotype cl 11.0 mm, cw 11.7 mm, off southwestern coast of Madagascar, Vauban, stn CH 94, 400 m (MNHN-B 18274); A, dorsal surface of carapace and P2; B, ventral view of anterior portion of body. Scale bars: A, 5 mm; B, 2 mm.

FIG. 2. — Ethusa abbreviata n. sp., holotype cl 13.8 mm, cw 14.5 mm, Vanuatu, N of Espiritu Santo, MUSORSTOM 8, stn CP 1124, 532-599 m (MNHN-B 27505); A, dorsal surface of carapace; B, ventral view of anterior portion of body; C, left G1, dorsal views; D, left G2, dorsal view. Scale bars: A, 5 mm; B-D, 2 mm.