Sakai, 1934
Carapace smooth and glossy, about 2.5 times as broad as long in both sexes, transversely dilated and sub-cylindrical, sloping rather steeply on the sides.
A very shallow transverse depression between the gastric and cardiac regions. Antero-lateral and postero-lateral margins convex; in the male, the former is marked with a rudimentary ridge with pubescence, in the female it is quite smooth. Posterior margin straight.
Front very narrow, truncate, not projecting beyond the anterior contour of the carapace, while in immature specimens the rostrum is bilobed and projects fairly well.
Cheliped smooth and slender, palm not exceedingly inflated even in the male. Fingers almost touching when closed, the tips sharply curved inward, crossing each other. No teeth on the cutting edges.
First pair of ambulatory legs feeble, second pair similar to the first but is a little larger; third leg very stout and strong, merus and propodus granulated along inner posterior margin, and sparsely hairy on either border; propodus about as long as broad, but the distal end tapers almost to the width of proximal end of dactylus, which is very stout and is as long as those of the preceeding pairs.
Fourth leg is similar to third, but is very much smaller and as long as the first pair and is sparsely tomentose on either border.
Of outer maxillipeds, merus-ischium joint is much more broader than in Pinnixia penultipedalis, carpus very long but scarcely reaches the end of dactylus, which is also long and spatulated. All the joints are furnished with feathered hairs and setae on the borders; the setae, at the distal end of the terminal and penultimate joints are exceedingly long and strong, the branches being sparse and nearly at right angles to the axis.
First two segments of male abdomen much shorter, third and fourth segments longest; penultimate segment constricted at the sides, seventh segment broad and rounded at the tip.
Female abdomen much broader and covers the whole surface of the sternum, no line of hair traverses the second segment contrary to the following species. (Sakai, 1934b)
Type locality: Momotori, Ise Bay, Japan.
Range: Japan - Ise Bay (Sakai, 1934b, 1939), Sagami Bay (Sakai, 1965b), Sagami Bay and Ise Bay (Sakai, 1976a).