Ethusa sexdentata ( Stimpson, 1858 )

Takeda, Masatsune, Ohtsuchi, Naoya & Komatsu, Hironori, 2021, Crabs (Crustacea, Decapoda) from the Sea off East and Southeast Asia collected by the RV Hakuhō Maru (KH- 72 - 1 Cruise) 1. Sulu Sea and Sibutu Passage, Bulletin of the National Museum of Nature and Science. Series A, Zoology 47 (2), pp. 65-97 : 80

Ethusa sexdentata ( Stimpson, 1858)

Material examined. RV Hakuhō Maru KH-72-1 cruise, sta. 12 (Sulu Sea ; 08°19.0′N, 118°09.1′E – 08°18.7′N, 118°08.5′E; 495–500 m deep); 3 m beam trawl; 26 May, 1972; 1 ˁ ( CB 5.5 mm; CL 6.0 mm) , NSMT-Cr 28970.

Remarks. The male specimen at hand agrees well with the males recorded by Stimpson (1858, 1907) in having the sharp external orbital tooth directed obliquely outward, and differs from the females illustrated by Sakai (1937, 1965, 1976), in which the external orbital tooth is stout and not tuberculated. In the present male, four frontal teeth are spiniform, weakly directed obliquely outward, and similar to, but shorter than the external orbital tooth; the tip of the frontal inner tooth slightly exceeds the tip of the frontal outer tooth; the tip of the external orbital tooth does not reach the basal part of the frontal teeth. The lateral margin of the carapace is directed obliquely outward, with the laterally convex branchial margin. The distal part of the whip-like G2 is sticking out from the subterminal part of the G1.

In the revision of the subfamily Ethusinae, Castro (2005) extensively studied all the Indo-West Pacific species of Ethusa including E. sexdentata . According to the monograph, E. sexdentata reported by Chen (1986) was misidentified and represents a new species, named by Castro (2005) as E. abbreviata .

Distribution. Known from Japan, Taiwan, the East and South China Seas, and the Philippines; 30–ca. 500 m deep.