(Fize & Serène, 1955a)
Carapace subquadrangular and longer than broad, depressed, anterior half broader than posterior half, surface covered with small and low granules in posterior half, larger and rather spiniform in anterior; median gastric region moderately convex and its posterior part only indistinctly separated from cardio-intestinal region, branchial regions hardly separated from both, mid-gastric and cardio-intestinal regions by very shallow furrows; front moderately concave and armed with spines of different size; internal orbital nearly reaching level of external; antero-lateral borders armed with spines and forming a convex lobe, lateral borders behind it straight or slightly converging. Cheliped slender; upper and external faces of merus, carpus and palm covered with fine granules. Upper face of coxae of third to fifth pereiopods with a small forward protruding lobe. (Türkay 1995)
Male, holotype of Pseudocryptochirus ishigakiensis Takeda & Tamura, 1979: Carapace subquadrangular and longer than broad, being depressed dorso-ventrally. Dorsum rather flat, moderately divided into convex regions; hepatic region isolated from adjacent regions anteriorly and internally by shallow furrows; mesogastric region moderately convex and rather sharply pointed anteriorly; metagastric region shallowly separated from cardiac and epibranchial regions; cardiac region rather rounded and weakly convex, separated from intestinal region very indistinctively; branchial region shallowly separated from cardiac region by antero-posterior furrow, but indistinctly from hepatic region.
Front moderately concave, and armed with spines of various size, its breadth being about one-third of carapace. Internal orbital angle rather rounded and spinulated, its anterior end scarcely going beyond external orbital angle, which forms a spinulated lobe together with anterior part of lateral border. Anterior one-fifth of lateral border gradually curved; from one-fifth to three-fifths, lateral border of both sides rather straight and parallel to each other; last part convergent posteriorly and continues smoothly to posterior border which is almost straight.
Buccal frame nearly as broad as half the carapace. Buccal cavity not entirely covered by third maxillipeds. Third maxilliped with a peculiar feature; ischium subtriangular, its antero-internal angle protruding forward, rounded and fringed with setae; merus a little longer than broad, its outer distal part scarcely protruding; exopod armed with setae and as long as half the outer margin of ischium.
Both chelipeds rather slender and equal in size. Merus covered with fine granules and its length about twice its breadth; its most part not hidden under carapace. Carpus only a little longer than broad and covered with granules, especially so on its upper surface; its upper distal part moderately protruding. Upper border of palm longer than its broad; upper and outer surfaces of palm covered with fine granules. Fingers nearly as long as upper border of palm, not toothed on cutting edges and meet along their whole length, leaving a short gape at proximal end; tips of fingers scarcely crossing each other.
First ambulatory leg comparatively slender and nearly as long as cheliped. Merus depressed laterally, a little shorter than twice its breadth, and covered with granules especially on its upper surface; proximal two-thirds of its upper border bears a low of setae; its lower surface covered with sparse setae. Carpus longer than broad, covered with granules and spines especially at its upper surface, its upper distal part moderately protruding. Propodus nearly as long as twice its breadth; its upper and outer surfaces covered with granules and spines. Dactylus smooth, curved inward, with its distal end pointed. Second ambulatory leg shorter and slenderer than the first, though generally similar to the latter in its character. Merus slightly depressed laterally, a little shorter than twice its breadth. Upper surfaces of merus, carpus and propodus covered with granules and spines. Dactylus smooth, curved inward, and its distal end pointed. Third ambulatory leg only slightly slenderer than, but nearly as long as the second; its character generally resembles that of the previous one, but more sparsely covered with granules. Fourth ambulatory leg the slenderest and the most cylindrical; its surface almost smooth, and only upper surface of merus covered with few numbers of granules. Upper surface of each coxa from second to fourth ambulatory legs with a small lobe protruded forward.
Abdomen elongate-oval, longer than broad and composed of seven segments, distal five segments being visible in ventral view. First segment hidden under carapace for its anterior half; its posterior border rather rounded. Second segment the narrowest, and broader posteriorly. Fourth segment the broadest, its length nearly one-third of its breadth. Fifth and sixth segments become narrower posteriorly. Last segment subtriangular. First and second pleopods fully developed, the first fringed with setae mainly at middle part of its external surface. (Takeda & Tamura, 1979)
Type locality: Nha Trang, Vietnam.
Range: Japan - Ishigaki-jima and Kuroshima, Okinawa (Takeda & Tamura, 1979); Vietnam - Nha Trang (Fize & Serène, 1955a, 1957).