(Sakai, 1978)
A large and stoutly-built crab, with very thick and hard exoskeleton. The carapace is transversely ovoid and anteriorly broadened. The dorsal surface is rather depressed and the regions moderately defined. Among the areolae of carapace, 2M, 3M, 2L, 1P are moderately convex and defined, but other areolae are ill-defined.
The frontal margin is well produced anteriorly beyond the preorbital eave, and its free margin narrow, double-edged, about one fourth the greatest breadth of the carapace. The median notch ill-defined.
The antero-lateral borders are markedly arched, divided into five teeth, of which the first and second are fused together, their margin is transverse in position and tuberculated. The third and fourth teeth are almost same size and the last one small and pointed.
Chelipeds are very unequal in both sexes, the right chela of male is very massive and long; the palm is very high and swollen. Both fingers are coloured in deep black except for their proximal portion. Ambulatory legs are almost same in form and size, but exactly, the second and third pairs are a little longer than the first and last pairs. (Sakai, 1978)
Type locality: Kimmei Sea Mount, Central Pacific, 35°22'N, 171°26'E, 300-320 m.
Range: Kimmei Sea Mount (Sakai, 1978, Guinot & Richer de Forges, 1981); Japan - Manazuru, Sagami Bay (Guinot & Richer de Forges, 1981), Sagami Bay and Wagu, Ise Bay (Sakai, 1983).