(Takeda & Miyake, 1969)
Originally referred to Microcassiope. Small species. Carapace transversely oval, moderately convex fore and aft as well as from side to side; dorsal surface well divided into areolae by rather deep, wide, smooth furrows; areolae provided with scattered brush-like hairs, covered with granules, most of which are beaded to form short, more or less undulating transverse or oblique rows. Antero-lateral border with four teeth excluding external orbital angle; teeth subacute at tips, directing obliquely forwards and somewhat upwards; posterior tooth more strongly directed obliquely outwards. Chelipeds massive, slightly unequal but alike each other; merus short, as large as carpus; outer surface of carpus extremely roughened by conical thick granules, depressions and granulated prominences; in smaller carpus prominences much pronounced than in larger carpus, more or less tuberculated; its inner angle armed with a granulated tubercular tooth; palm also roughened by granulated prominences somewhat like in carpus, provided with scattered brush-like hairs; blackish brown colour of immovable finger fairly extended back onto palm towards upper border and along lower border; tip of each finger blunt, but its inner surface considerably excavated. Ambulatory legs hairy, armed with sharp granules; merus bordered with a row of sharp granules on upper border; subterminal depression of upper border fairly distinct; carpus and propodus also granulated on and near upper borders; upper border of dactylus armed with small but spiniform granules. (Takeda, 1998)
Description of holotype: The carapace is transversely oval and moderately convex fore and aft as well as from side to side; the dorsal surface is well divided into areolae by rather deep, wide smooth furrows; the areolae are provided with scattered brush-like hairs, and covered with granules, most of which are beaded to form short, more or less undulating transverse or oblique rows; a frontal region and an areola 1M are small but rather convex, and 2M is the most prominent, being indistinctly incised from the middle of the anterior border by a longitudinal shallow furrow continuous with the furrow of the outside of 1M; just near the incision are some longish brush-like hairs; an antero-lateral areola behind the external orbital angle, which represents 1, 2 and 3L, is indistinctly subdivided into three; 3M is also very indistinctly subdivided into three by the transverse incision from each of the lateral angles and by the longitudinal one from the middle of the posterior border; the anterior process of 3M ends at the middle way of 1M; the areolae 4, 5 and 6L are distinct, but 4L is small and placed near the third antero-lateral tooth; at the postero-lateral surface of the carapace, an oblique furrow is prominent and continuous with a transverse furrow behind the areola 3M; along the posterior border of the carapace is a transverse prominence that is interrupted in the middle.
The front is double-rimmed, bearing a median, large V-shaped sinus; in dorsal view the lower border is visible only near the median sinus beyond the upper border which may represent the areola 1F; both borders are most produced near the median sinus and furnished with a row of rounded granules, being continuous laterally through the depression with the strongly protruded lateral lobule of the front; the lobule is somewhat distinctly curved downwards and separated from the supraorbital angle by a very deep notch. The eyestalk is very stout and armed with several granules just near the cornea and at the proximal part. The supraorbital border is somewhat raised and prominently granulated most at its inner part; there are two depressions, but they are not deep; just below the external orbital angle which is weakly produced, a notch is present, and the lateral angle of the infraorbital border is angulated. The subhepatic region is prominently granulated and hairy.
The antero-lateral border of the carapace is armed with four teeth excluding the external orbital angle; the teeth are subacute at the tips, directing obliquely forwards and somewhat upwards; the posterior tooth is more strongly directed obliquely outwards than the preceeding one; the first is slightly smaller than the last three subequal teeth. The postero-lateral border is strongly convergent and near the posterior end it is directed downwards; its dorsal surface is granulated and most strongly sunken near the posterior border of the carapace.
The chelipeds are massive and slightly unequal but alike each other, the left one being the larger. The merus is short and as large as the carpus; its inner surface is wholly excavated and concealed beneath the carapace, being fringed with brush-like hairs and minute granules without spine. The outer surface of the carpus is extremely roughened by the conical thick granules, depressions and granulated prominences; in the smaller carpus the prominences are much pronounced than in the larger carpus, and more or less tuberculated; the inner angle is armed with a granulated tubercular tooth. The palm is also roughened by the granulated prominences somewhat like in the carpus, and provided with scattered brush-like hairs; along the outer upper surface is a longitudinal furrow, and at the middle surface are two which are, however, very obscure and only traceable due to the indistinct rows of granules; at the surface near the lower border the granules become indistinct, diminishing the size; the blackish brown colour of the immovable finger is fairly extended on to the palm towards the upper border and along the lower border. The cutting edge bears three or four rather blunt teeth of different size; the tip of each finger is blunt, but in reality its inner surface is considerably excavated.
The ambulatory legs are hairy and armed with sharp granules. The merus is bordered with a row of sharp granules on the upper border; the subterminal depression of the upper border is fairly distinct. The carpus and propodus is also granulated on and near the upper borders; in the carpus a row of granules on the upper surface along the upper border is more or less ridge-like. The upper border of the dactylus is armed with small but spiniform granules; in each dactylus of the last two ambulatory legs a subterminal spine on the lower border is prominent. (Takeda & Miyake, 1969f)
Type locality: off Sone, Munakata-Oshima Islet, Fukuoka Prefecture, Japan, 10 m.
Range: Japan - Fukuoka Prefecture (Takeda & Miyake, 1969f), Amakusa (Yamaguchi et al., 1976), Mage-jima, Kagoshima Prefecture, Sagami Bay, Toyama Bay, east coast of Kii Peninsula and Amakusa (Takeda, 1977b).