Stimpson, 1857
The carapace is triangular in outline, the dorsal surface not much convex; the regions are fairly well defined. The gastric region is armed with two or three tubercles in the median line and one on either side of the median gastric one, also a few minute tubercles irregularly disposed among them. Cardiac region little convex and mounted with an obtuse tubercle; intestinal region with a medium-sized tubercle. The hepatic region continuous with the postocular cup, having a sharp spinule near the posterior end; the branchial region has an oblique row of three tubercles along the lateral border, of which the middle one is very large; this row is followed by a prominent, forwardly pointed epibranchial spine placed at the junction of the antero-lateral and postero-lateral borders.
The pseudorostral spines are flattened and laminiform, their outer border being convex. The supraocular eaves are thin and armed with acuminate preocular spine; the upper orbital sinus very narrow. The ridge of the pterygostomial region is irregularly marked with 4 or 5 tubercles. The infraorbital lobe is rudimentary. The basal antennal segment is broad and armed with a terminal tooth; the two following segments are compressed.
Chelipeds of both sexes are much stouter than the ambulatory legs, the arm is prismatic, its lower and inner borders are cristate; wrist with its inner border cristate and its superior and outer surfaces irregularly ridged; the palm is smooth and laterally compressed, upper and lower edges being sharply cristate; fingers of both sexes not gaping and armed with about 10 or 11 triangular teeth. Merus, carpus (and also propodus of posterior two pairs) of the ambulatory legs are fringed with feathered hairs along the anterior and posterior borders. Dactylus is acuminate and curved at tip, its posterior margin being armed with two rows of minute denticles, which are concealed beneath the pubescence.
Abdomen of both sexes composed of seven distinct segments. (Sakai, 1938: 287)
Type locality: Hakodate Bay, Hokkaido, Japan, 10 m.
Range: Japan - Hakodate Bay (Stimpson, 1857c), Osaka Bay (Miers, 1886), Mutsu Bay (Yokoya, 1928), Tokyo Bay and Sagami Bay (Parisi, 1915b), from Tsugaru Strait southwards to north of Inubo-zaki and to north of Oga (Yokoya, 1933), Shiriya-zaki (Sakai, 1938a), Sagami Bay (Sakai, 1965b), Siriya-zaki and Sagami Bay (Sakai, 1976a), Nezumigaseki, Yamagata Prefecture (Suzuki S., 1979), Rishiri, Funka Bay and Otanoshike (Komai et al., 1992), Soya Strait (Takeda & Miyauchi, 1992); Korea - Aninjin and Hae-undae (Kim, 1973); Yellow Sea (Takeda & Miyake, 1972c); 10-160 m.