Sakai, 1939
Carapace markedly broadened posteriorly and is rounded trapeziform in outline, the front not produced beyond the outline of the carapace; the postero-lateral borders are shorter than the antero-lateral and are slightly convex; the posterior border usually markedly concave in the middle. The dactylus of the external maxillipeds does not reach the tip of the propodus, although in a few cases the former exceeds the latter.
Fingers of chelipeds are much shorter than the palm, the movable finger has a tooth near the basal third, while the immovable one bears two small ones near the base. The first pair of ambulatory legs are shortest, anterior three pairs of legs are equally thicker than the last pair which are, although shorter than the penultimate pair, distinctly longer than the anterior two pairs. The dactyli of the anterior two pairs are short and claw-shaped; those of the last pair are characterized in having longish hairs on inner border and also around the whole surface in distal half; near the distal end of the posterior border, there are two rows of 10 to 18 brown setae, which increase in size distally.
The present species seems to be a nearest kin of Pinnotheres similis Bürger from Philippine, the only point of difference being the proportional length of the ambulatory legs, i.e. in similis, the third pair of legs are figured relatively shorter than in the present species; no mention was made about the hairs of the dactylus of the last pair in P. similis. (T. Sakai, 1939: 584)
Type locality: Nanaki Shirahama, Kii Peninsula, Japan.
Range: Japan - Nanaki Shirahama (Sakai, 1939), Seto Kanayama (Sakai, 1976a).