Takeda & Nakasone, 1991
Male (holotype): Carapace rhombic, almost as wide as long, or only slightly wider than long; dorsal surface strongly convex as a whole, smooth except for mesogastric and cardiac regions and a ridge of each branchial region, being fringed with a row of vesiculate granules except for frontal and supraorbital margins. Mesogastric part indicated anteriorly with a median line of several small granules and laterally with a line of vesiculate granules of good size directed toward each hepatic region; metagastric part with a cluster of vesiculate granules, being separated from cardiac region by a shallow transverse furrow. Cardiac region strongly raised, subtruncated dorsally, covered with a cluster of vesiculate granules. Branchial region provided with a ridge running from median part of postero-lateral margin of carapace; its anterior or distal half longitudinal and posterior or proximal half oblique. Hepatic region feebly demarcated, its margin weakly convex and fringed with small granules; subhepatic facet well formed, rather concave so as to be narrow in dorsal view, with margin weakly convex and beaded with more than ten granules; anterior part of branchial margin or posterior part of antero-lateral margin of carapace directed outward just behind hepatic margin, then changed its direction to lateral angle of branchial region or of carapace, which is rather angulated; posterior margin of branchial region or postero-lateral margin of carapace beaded with a line of fused granules of good size, its median part being angulated and raised. Posterior margin of carapace weakly concave, with a small median protuberance and angulated lateral ends of both sides.
Frontal region weakly concave, and its margin weakly concave in dorsal view, with a small median protuberance.
Chelipeds not heavy, covered with small granules. Merus granulated along both anterior and posterior margins and on upper surface as a longitudinal belt. Carpus smooth along its outer margin. Palm long and granulated along anterior and posterior margins and on median convex part of upper surface. Fingers one and half times as long as palm, narrowly gaped.
Ambulatory legs slender, smooth. Sternum rather concave as a whole, with thickened and granulated margins along bases of ambulatory legs. Abdominal fossa fringed with beaded granules along anterior two sternites.
Male abdomen long, with three pieces; proximal piece linear and mostly hidden under posterior margin of carapace; median piece prominent, with three vestigial incisions at each side, being provided with an obtuse tubercle covered with vesiculate granules at terminal part; distal piece narrow, ca. 1/3 as long as median one.
First pleopod long, not curved, with twisted distal part.
Ovigerous female (palatype). The carapace is not much different from that of the holotype male, with quite same areolation and granulation, but the areolae are comparatively shallowly isolated and the lateral angle of the branchial region or of the carapace is only obtusely angulated as well as each lateral end of the posterior margin of the carapace. The third maxilliped is provided with a line of long hairs on the merus and ischium unlike in the case of the holotype male. The abdomen is composed of four pieces; the proximal two are short and wholly covered with vesiculate granules; the main piece is almost smooth except for small marginal spaces and also for median proximal and distal parts; the distal piece is rather long and ellipsoidal. (Takeda & Nakasone, 1991)
Type locality: estuary of Oura River, Okinawa-jima, Japan.
Range: Japan - Okinawa-jima (Takeda & Nakasone, 1991).