Sakai, 1965
Carapace convex, broader than long, minutely granular and provided with some tubercles on the surface. Front two-lobed. Behind the orbital angle there are six marginal tubercular teeth on each side; in these tubercular teeth at the third one the carapace is broadest and the last one is on the posterior margin. On the dorsal surface two tubercles are on the medial line, the anterior cardiac and the posterior intestinal ones. The cardiac tubercle is near the middle of the carapace. An obliquely elongated tubercle, which is in some specimens divided into two round tubercles, is on the gastric region, another round one on the hepatic and three are on the branchial region. The pterygostomial tubercle, which is noticeable in dorsal view, is continuous to the outer anterior corner of the buccal area as an obtuse ridge.
Two pairs of the antennae are comparatively well developed. The antennular fossa is communicated with the orbit. In the third maxilliped, the exognath is nearly as wide as the endognath; in the latter the merus is a little shorter than the basi-ischium measuring along the inner border. Chelipeds subequal; palm shorter than finger. Succeeding four legs subcylindrical and almost subequal in length, but first longer and successively diminished in length to the posterior leg.
The abdomen in male consists of five segments: the proximal two are very short, the third is longer and broader than any of others. The terminal segment is long and narrow, terminally rounded. In the female, it is four-segmented. (Yokoya, 1933)
Type locality: Tosa Bay, Japan.
Range: Japan - off Tanabe, Muroto-misaki, Bungo Strait, south of Kagoshima and west of Amakusa (Yokoya, 1933), Mikawa Bay and Tosa Bay (Sakai, 1976a), Susami-cho, Wakayama, Tosa Bay and Tsuyazaki (Muraoka, 1998).