Sakai, 1934
Carapace depressed, antero-lateral borders forming a very slender shoulder, and are finely granulated and hairy along the borders. The lateral angle of the carapace projecting laterally and posteriorly, behind which the postero-lateral borders rapidly converge and are concave. Posterior border straight, one third as broad as the maximum breadth of the carapace. Front deflexed and bilobed, slightly produced beyond the eyes in normal position.
A sharp transverse ridge on the cardiac region; a broad lateral groove between the gastric region and the cardiac ridge and occupies one third the carapace in length; otherwise the carapace is smooth and flat up to the frontal region.
Chelipeds equal, with thick hairs along the margins; chelae strongly compressed, with a number of longitudinal rows of setiferous granules on the outer surface of the hand; fingers tapering distally and meet with sharp denticles on the cutting edges.
First and second pairs of ambulatory legs slender and smooth, the latter a little longer, the dactyli long and straight, as long as the penultimate segment in both cases. Third pair stout, especially in the merus, and is thickly fringed with hair; the posterior margin coarsely granulated and the upper surface tomentose; dactylus sharp, but is shorter than that of the preceeding pair. Last pair shortest and very slender, all the segments being thickly fringed with hair; dactylus also shortest.
Outer maxilliped is similar in shape to that of Pinnixa penultipedalis, but all segments are not in the same plane. Merus-ischium is slightly directed upward, carpus downward, propodus laterally inward, but the terminal joint is again turned obliquely upward.
The terminal joint is strongly elongated and spatulated, reaching nearly to the base of merus-ischium, and is thickly fringed with very long feathered hairs as well as in the penultimate joint.
Of female abdomen, all the seven segments are distinct; first and second segments are narrower, with a row of short hair between second and third segments; terminal segment concave in the middle. (Sakai, 1934b)
Type locality: Izu Shimoda, Japan.
Range: Japan - Izu Shimoda (Sakai, 1934b, 1939, 1976), Ariake-kai (Miyake, 1961), Nanki Shirahama (Miyake, 1983).