Ethusa barbata, 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 : 515-516

Ethusa barbata n. sp.

( Fig. 5 )

TYPE MATERIAL. — Holotype: juv. cl 6.8 mm, cw 6.9 mm, SALOMON 1, stn CP 1804 ( MNHN-B 28707 ).

TYPE LOCALITY. — Solomon Islands, north of Guadalcanal island, 09°32.0’S, 160°37.4’E, 309- 328 m.

MATERIAL EXAMINED. — Solomon Islands. SALOMON 1, stn CP 1804, 09°32.0’S, 160°37.4’E, 309-328 m, 2.X.2001, 1 holotype ( MNHN-B 28707).

ETYMOLOGY. — From barba (Latin for beard) in reference to the very conspicuous and long setae on the dorsal and most of the ventral surfaces of the carapace and on the pereopods.

DISTRIBUTION. — Known only from the Solomon Islands. Depth: 309-328 m ( Fig. 34 ).

SIZE. — Maximum size: cl 6.8 mm, cw 6.9 mm (MNHN-B 28707), unknown.

DESCRIPTION

Carapace of females (males unknown) almost as broad as long; dorsal surface covered by very conspicuous, long, abundant hair (consisting of simple plumose setae), particularly longer (up to 1.9 mm) along anterolateral borders ( Fig. 5A ). Urogastric, cardiac, branchial regions elevated, covered by slightly longer hair consisting mostly of plumose setae. Branchial regions slightly inflated along sides. Lateral borders diverge toward posterior border.

Anterior border of carapace ( Fig. 5A ) with proximally broad outer orbital teeth with slender, straight tips, not reaching slightly shorter frontal teeth. Frontal teeth short, broadly triangular, nearly equal. Orbital sinuses broad, V-shaped, asymmetrical (inner margins steeper than outer margins); lateral frontal sinuses shallow, U-shaped; median frontal sinus V-shaped, about as wide as lateral frontal sinuses, narrower than orbital sinuses.

Anterior border of endostome ( Fig. 5B ) well above anterior border of antennular fossae of basal antennular articles, reaching ventral fold of median frontal sinus.

Female chelipeds (P1) (males unknown) small, slender, smooth, nearly equal; dorsal and ventral margins of all articles with simple and plumose setae, number and relative length increasing proximally; fingers 1.1 times longer than propodus, with very short, rounded teeth.

P2, P3 relatively short; dorsal, ventral margins of all articles with simple plumose setae; length of

A P2 meri 1.5 times cl, 4.6 times longer than broad. P4, P5 covered with long, mostly plumose setae, P5 dactyli thick, slightly curved.

Female abdomen (males unknown), with six somites, somites 1-4 covered with short setae, triangular telson with broadly rounded tip; somite 3 broadest, somite 6 longest.

REMARKS

Ethusa barbata n. sp. is being described as a new species even if it is known from only a small female. This female clearly does not belong to any of the seven species of Ethusa known so far only from males: E. crassipodia n. sp., E. curvipes Chen, 1993 , E. furca Chen, 1993 , E. indonesiensis Chen, 1997 , E. magnipalmata Chen, 1993 , E. parapygmaea Chen, 1993 , and E. philippinensis Sakai, 1983 . Its very conspicuous pubescence is shared with three other species of Ethusa ( E. foresti Chen, 1985 , E. hirsuta McArdle, 1900 , and E. izuensis Sakai, 1937 ) that show a generalized, although not as conspicuous, pubescence over the carapace. None of these three species, however, show the straight, basally expanded, and short outer orbital teeth as well as an endostome with its anterior border that reaches as high as the ventral fold of the median frontal sinus, both characters diagnostic to E. barbata n. sp.

Figures

FIG. 5. — Ethusa barbata n. sp., juv. holotype cl 6.8 mm, cw 6.9 mm, Solomon Islands, N of Guadalcanal, SALOMON 1, stn CP 1804, 309-328 m (MNHN-B 28707); A, frontolateral portion of dorsal surface of carapace, most setae removed along right anterior margin; B, ventral view of anterior portion of carapace. Scale bars: A, 1 mm; B, 2 mm.

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