Ethusina huilianae, 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 : 582-583

Ethusina huilianae n. sp.

( Figs 29 ; 30 )

TYPE MATERIAL. — Holotype: cl 12. 7 mm, cw 13.0 mm, MUSORSTOM 9, stn CP 1277 ( MNHN-B 28727 ); paratypes: cl 11.8 mm, cw 11.9 mm, MUSORSTOM 9, stn CP 1278 ( MNHN-B 28728 ); cl 12.6 mm, cw 12.6 mm, same station ( MNHN-B 28729 ).

TYPE LOCALITY. — French Polynesia, Marquesas Islands, off Eiao island, 07°52’S, 140°39’W, 1000- 1100 m.

MATERIAL EXAMINED. — French Polynesia. Marquesas Islands, MUSORSTOM 9, stn CP 1277, 07°52’S, 140°39’W, 1000-1100 m, 5.IX.1997, 1 holotype ( MNHN-B 28727). — Stn CP 1278, 07°52’S, 140°39’W, 1000 m, 5. IX.1997, 1 paratype ( MNHN-B 28728), 1 paratype ( MNHN- B 28729).

Austral Islands, BENTHAUS, stn CP 1966, 23°21.3’S, 149°34’W, 636-1200 m, 19.XI.2002, 1 ( MNHN-B 28834).

ETYMOLOGY. — This new species is named after Huilian Chen (Chen Hui-Lian), who lead the way to this and other studies on Indo-West Pacific dorippid crabs and who first recognized this species as a new one. DISTRIBUTION. — Known only from the Marquesas and Austral islands, French Polynesia. Depth: 1000- 1100 m; also collected in a trawl from 636-1200 m ( Fig. 34 ).

SIZE. — Maximum size: cl 12.7 mm, cw 13.0 mm (MNHN-B 28727), unknown.

DESCRIPTION

Carapace ( Fig. 29 ) slightly broader than long or as broad as long in males (females unknown); dorsal surface with sparse setae, small, conspicuous granules. Mesogastric, urogastric, cardiac regions elevated, urogastric region bordered by conspicuous lateral grooves; cervical groove shallow and partially visible; branchial grooves shallow but conspicuous at sides. Branchial regions conspicuously inflated along sides.

Anterior border of carapace ( Fig. 29 ) with very slender, outwardly directed, acutely tipped outer orbital teeth, longer than but not reaching frontal teeth. Lateral frontal teeth slender, acutely tipped, equal or slightly longer than triangular median frontal teeth. Orbital sinuses broad, V-shaped; asymmetrical, inner margins oblique, outer margin nearly straight; lateral frontal sinuses U-shaped, asymmetrical; median frontal sinus V-shaped, as wide as lateral frontal sinuses but narrower than orbital sinuses.

Eye peduncles ( Fig. 30A ) wide, longer than cornea, 2.1 times eye diameter. Eyes and distal portion of eye peduncles visible dorsally.

Anterior border of endostome ( Fig. 30A ) lies well below posterior border of antennular fossae of basal antennular articles.

Male chelipeds (P1) ( Fig. 29 ; females unknown) smooth, equal or nearly equal; propodi swollen, as long as or slightly longer than fingers; fingers slender, with broad cutting edges.

P2, P3 ( Fig. 29 ) slender, articles granular except dactyli; length of P2 meri 1.0-1.1 times cl, P2 meri 7.5-8.2 times longer than broad. P4, P5

Ethusinae of Indo-West Pacific ( Crustacea, Brachyura , Dorippidae )

with short hairs; P5 dactyli relatively slender, curved.

Male abdomen ( Fig. 30B ) with four somites (3-5 fused, basal half swollen), triangular telson. Somite 1 length 2.5-2.7 times as broad, somite 6 rectangular.

G1 ( Fig. 30C ) very slender; distal third narrow, straight, each tip slightly rounded, short spines along tip, inner margins; G2 ( Fig. 30D ) relatively short, each distal part broad; curved distal end, pointed tip.

REMARKS

Ethusina huilianae n. sp. is known from four male specimens. It is close to E. crenulata n. sp., a seemingly sympatric species from French Polynesia, and to E. isolata n. sp., known only from the Hawaiian Is. Differences between the three species are discussed in the description of E. crenulata n. sp. (see above) and in Table 1. There are also similarities with E. stenommata n. sp. Differences are discussed in the description of the latter species (see above).

A male from the Austral Is, French Polynesia (cl 13.3 mm, cw 13.0 mm, MNHN-B 28834) shares all diagnostic characters with the remaining three Marquesas Is males except for slightly shorter and stouter P2 and P3 (P2 meri 0.9 times cl, P2 meri 6.9 times longer than broad), slightly stouter G1 and G2, and slightly shorter frontal teeth. The collection of additional specimens is needed to test for the possibility that these are species-specific differences.

Figures

FIG. 29. — Ethusina huilianae n. sp., holotype cl 12.7 mm, cw 13.0 mm, French Polynesia, Marquesas Islands, Eiao, MUSORSTOM 9, stn CP 1277, 1000-1100 m (MNHN-B 28727).

FIG. 30. — Ethusina huilianae n. sp., holotype cl 12.7 mm, cw 13.0 mm, French Polynesia, Marquesas Islands, Eiao, MUSORSTOM 9, stn CP 1277, 1000-1100 m (MNHN-B 28727); A, ventral view of anterior portion of body; B, abdomen; C, right G1, ventral view; D, right G2, ventral view. Scale bars: A, B, 3 mm; C, D, 2 mm.

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