Stimpson, 1858
Carapace transversely cylindrical, about twice as broad as long: surface smooth, a pair of curved shallow grooves between the gastric and cardiac regions. Front narrow, dorsal surface with a longitudinal groove in the median, and the anterior margin truncated on dorsal view. Orbital margin with a smooth carina, eye-peduncle stubby. Antero-lateral portion inflated and convex. Postero-lateral margin slanting and concave in the median. Posterior margin a little convex. Ischium and merus of the third maxillipeds fused together, inner margin with long setae; propodus narrow and elongate, with basal portion broader than the distal one; dactylus broadened distally and extended beyond the distal end of propodus; the two joints both with long setae at the tips.
Chelipeds stout. Merus thickly covered with short hairs on the margin and the inner surface. Carpus triangular, dorsal surface convex. Palm gradually broadening distally; outer surface smooth and punctate, inner surface with sparse short hairs; ventral margin finely granulated, distal half of the ventral margin with more distinct granules extending to the basal half of the lateral surface of the immovable finger. The movable finger with a large triangular tooth nearly at the middle, and 3-4 granules at the base on the inner margin. The immovable finger finely and sparsely granulated; fingers widely gaping. First 2 ambulatory legs short, small and smooth; the third one the stoutest, its merus with granules and short hairs on the posterior margin; the last legs the shortest.
Male abdomen narrow and long; telson with distal margin obtuse. Female abdomen circular. Carapace length of the male 4 mm, breadth 7.8 mm; of the female, length 4.6 mm, breadth 8 mm. (Dai & Yang, 1991)
Type locality: Hakodate Bay, Japan.
Range: Japan - Hakodate Bay (Stimpson, 1858b, 1907), Moura, Mutsu Bay (Yokoya, 1928), Moura and Asamushi (Sakai, 1939), Mutsu Bay (Sakai, 1976a), Muroran, Tomakomai, off Toyotomi, and Kushiro (Komai et al., 1992), Oga Peninsula; Korea - Daenanji Island (Kim, 1973); China - Beidaihe and Yantai (Shen, 1932), Beidaihe, Yantai, and Qingdao (Shen, 1937), Shandong Peninsula and Bohai Bay (Dai & Yang, 1991).