Ortmann, 1893
The carapace behind the orbits is elongate pyriform, the dorsal surface beneath the tomentum is smooth and glabrous. The gastric region is convex and mounted with an obtuse tubercle on the summit, the cardiac region slightly swollen, intestinal region mounted with a tubercle which in the female is almost obscure, the branchial regions are rounded, no epibranchial spine at all.
The pseudorostral spines are about half as long as the carapace proper and are parallel with each other but slightly divergent at tip. The preocular spine indistinct, the sinus between the supraocular eave and the postocular cup is very narrow.
The basal antennal segment is very narrow, its distal end unarmed; and the tooth on the outer margin near base is also very indistinct. The pterygostomial region has two tubercles, of which the anterior one is prominent.
Chelipeds and ambulatory legs are similar to those of Hyastenus diacanthus. (Sakai, 1938: 281)
Type locality: Tokyo Bay and Sagami Bay, Japan.
Range: Red Sea - Elat (Griffin & Tranter, 1974); Amirante Islands (Rathbun, 1911); Maldives; Japan - Tokyo Bay and Sagami Bay (Ortmann, 1893), Tateyama Bay, Shimoda, Wakayama, Gobo and Nagasaki (Sakai, 1938a), Sagami Bay (Sakai, 1965b), from Tokyo Bay southward to Nagasaki (Sakai, 1976a), Amakusa (Yamaguchi et al., 1976), off Nojima-zaki, Boso Peninsula (Takeda, 1981a), off Goto-retto and Nagasaki (Griffin & Tranter, 1986a); Korea - Pusan and Cheju-do (Kim, 1970), Hae-undae (Kim, 1973); East China Sea (Griffin & Tranter, 1986a); South China Sea - between Xiamen and Hong Kong (Griffin & Tranter, 1986a); 30-180 m.