Ethusa foresti Chen, 1985

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 : 520-521

Ethusa foresti Chen, 1985

( Fig. 8 )

Ethusa foresti Chen, 1985: 195 , figs 13, 14, pl. 2, figs 7, 8; 1993: 317 (key), 318 (list).

TYPE MATERIAL. — Holotype: cl 8. 1 mm, cw 7.7 mm, MUSORSTOM 2, stn CP 72 ( MNHN- B 18166); paratypes:, MUSORSTOM 2, stn CP 10 ( IOAS); cl 7.5 mm, cw 7.5 mm, MUSORSTOM 2, stn CP 20 ( MNHN-B 18167 ); cl 6.7 mm, cw 6.5 mm, MUSORSTOM 2, stn CP 68 ( MNHN- B 18168).

TYPE LOCALITY. — Philippine Islands, South China Sea coast off Luzon, 14°00.7’N, 120°19.4’E, 182- 197 m.

MATERIAL EXAMINED. — Philippine Islands. MUSORSTOM 2, stn CP 20, 14°00’N, 120°18’E, 185-192 m, 22.XI.1980, 1 paratype ( MNHN-B 18167). — Stn CP 68, 14°01’N, 120°18’E, 195- 199 m, 29. XI. 1980, 1 paratype ( MNHN-B 18168). — Stn CP 72, 14°00.7’N, 120°19.4’E, 182- 197 m, 30. XI.1980, 1 holotype ( MNHN-B 18166).

MUSORSTOM 3, stn CP 96, 14°00’N, 120°18’E, 190-194 m, 1.VI.1985, 1 ( MNHN-B 18882). — Stn CP 97, 14°00’N, 120°16 ’E, 189-194 m, 1.VI.1985, 1 ( MNHN-B 18278). — Stn CP 101, 14°00’N, 120°19’E, 194-196 m, 1.VI.1985, 1 ( MNHN-B 18881). — Stn CP 145, 11°01’N, 124°04’E, 214-246 m, 7.VI.1985, 2, 1 parasitized by Sacculina sp. ( MNHN-B 18880).

DISTRIBUTION. — Known only from the Philippine Is. Depth: 182-246 m ( Fig. 34 ).

SIZE. — Maximum size: cl 7.8 mm, cw 6.1 mm (MNHN-B 18278), cl 9.9 mm, cw 10.0 mm (MNHN-B 18880).

REMARKS

Ethusa foresti is close to another small-size species, E. izuensis Sakai, 1937 . Diagnostic to E. foresti are long and slender P4 and P5 dactyli ( Chen 1985: fig. 13), coarse granulation on the dorsal surface of the carapace, and outer orbital teeth that typically are directed inwardly. In contrast, E. izuensis is characterized by much shorter P4 and P5 dactyli ( Sakai 1965: pl. 12, figs 1, 2; 1976: fig. 29; Chen 1985: fig. 11; Chen & Sun 2002: fig. 103.1), lower and sparser granules on the carapace, and outer orbital teeth that are directed outwardly. In both species the anterior border of the endostome reaches the antennular fossae of the antennular fossae of the basal antennular articles ( Chen 1985: fig. 12a; Chen & Sun 2002: fig. 103.2 for E. izuensis ).

Ethusa foresti may also be confused with small specimens of E. orientalis Miers, 1886 , from the southwestern Pacific since in some specimens the outer orbital teeth may slightly be directed inwardly. In E. orientalis the teeth are typically straight and more triangular, and the granules of the carapace are smaller than in E. foresti .

The G1 is here illustrated for the first time ( Fig. 8 ). Each distal end is spade-like, with an acute tip, and sparse, very short spines. In contrast, each G1 of E. izuensis has a slender, slightly expanded distal end and a row of longer, more conspicuous spines ( Chen 1985: fig. 12f, h; 1986: fig. 12.61; Chen & Sun 2002: fig. 103.7).

Figures

FIG. 8. — Ethusa foresti Chen, 1985, cl 7.8 mm, cw 6.1 mm, Philippine Islands, SW of Luzon, MUSORSTOM 3, stn CP 97, 189-194 m (MNHN-B 18278), right G1 with distal end of G2 in situ, ventral view. Scale bar: 1 mm.

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