(Takeda & Miyake, 1969)
Originally referred to Lithocheira. Small species. Carapace transverse, weakly declivous anteriorly; its dorsal surface naked for its greater part, ill-defined only with a short thick felt along frontal and antero-lateral borders. Frontal breadth about one-third breadth of carapace, fronto-orbital breadth about twice frontal breadth, almost equal to length of carapace. Antero-lateral border cut into three distinct but low teeth; a very small tooth produced on posterior slope of third tooth; first tooth indicated as a weakly arched ridge; second tooth more or less conical with a tip near its anterior end, its posterior slope arched; third tooth bears a tip at its anterior end, generally arched at outer border; a small fourth tooth obscurely demarcated as a small granule. Postero-lateral border weakly convergent, longer than antero-lateral border, dorsally covered with a pubescence, with small rounded granules. Posterior border wide, rimmed along whole length, weakly concave at its middle. Chelipeds nearly equal; merus unarmed only with a crest of upper border; carpus nearly naked, glabrous; distal inner margin coarsely granules with short, dense brush-like hairs; inner angle pronounced, tipped with a spiniform granules, fringed with a row of several long simple hairs long its inner slope; larger palm entirely smooth, naked, smaller palm provided with some long hairs and rounded granules near upper border; movable finger somewhat vertical due to stout, rather short immovable finger. Ambulatory legs long, stout; upper border of merus thin, minutely serrated, with prominent subterminal interruption; upper border of carpus fringed with short setae and some long hairs; propodus also fringed with short thick setae and long hairs along both borders; dactylus as long as propodus, densely covered with short setae and long hairs; in last pair dactylus weakly curved upward near tip. (Takeda, 1998)
Description of holotype: The carapace is transverse and somewhat rectangular; the dorsal surface is only slightly declivous anteriorly and almost flat posteriorly as well as from side to side; the greater part of the surface is entirely named and glabrous; there is no distinct indication of regions except for the shallow, median longitudinal furrow and the gastro-cardiac transverse depression as usual; however, in reality, the posterior surface just in front of the posterior border is so shallowly depressed that the cardiac region is very obscurely demarcated; along the frontal, supraorbital and antero-lateral borders the dorsal surface is provided with a very short, light brown felt, in which several longish hairs are implanted; in addition, a row of longish brush-like hairs runs transversely behind the front; the antero-lateral surface which is covered with the felt is also rendered distinct by shallow depression; in the felt the small rounded granules are rather sparsely embedded.
The frontal breadth is about one-third the breadth of the carapace, and the fronto-orbital breadth is about twice the frontal breadth and almost equal to the length of the carapace. The front is declivous and cut into two lobes by a median small notch; each lobe is only slightly rounded near the notch, its lateral angle being not produced in a distinct angle. The supraorbital border is entire, very minutely granulated and fringed with brush-like hairs that are more prominent along the inner part of the border; the external orbital angle is slightly pronounced, angular and confluent with the anterior lobe of the antero-lateral border. The infraorbital border is also very indistinctly granulated and almost entire only with a shallow excavation below the external orbital angle; the inner part of the border is hardly sinuated, its inner angle being low and rounded. The eyestalk is swollen and provided with several short brush-like hairs on the upper surface; the cornea is prominent and chiefly terminal and ventral; they are tightly retractile in the orbit and anteriorly protruded from the general contour of the carapace, but freely movable in the orbit.
The antennule is somewhat obliquely folded in the fossa which is formed below the front by a well developed anterior process of the epistome and the antennular basal segment; the posterior and outer lateral borders of the fossa is rimmed by a crest-like ridge; otherwise, a somewhat oblique ridge is present just outside of and parallel to the outer lateral border of the fossa. The antennal basal segment, which is truly the second, is not reached the short ventral prolongation of the front; however, its outer angle is raised higher than the inner infraorbital angle, and the inner end of the infraorbital border is touched with the middle way of the segment, so that an inclined V-shaped notch is formed between the segment and the inner infraorbital angle; the next segment is almost half the length of the former and reached the lateral angle of the front; the antennal flagellum is provided with scant microscopical secondary hairs and exceeds twice the length of the major diametre of the orbit.
The third maxilliped is broad. The ischium is glabrous and ornamented with a median longitudinal shallow groove; its antero-inner angle is weakly extended forward and rounded; the inner margin of the ischium is thin and almost entire with sparse hairs. The merus is subquadrate and slightly narrower than the ischium, its anterior margin being markedly thin; its exposed surface is ornamented with two prominent depressions, one just inside the postero-inner angle and the other along the anterior and outer margins, so that a low prominence is obliquely demarcated at the middle of the surface.
The antero-lateral border of the carapace is cut into three distinct but low teeth; furthermore a very small tooth is produced on the posterior slope of the third tooth; those teeth are so thin that they are crest-like and light-coloured in life and also in spirit; the first is a mere ridge that is weakly arched and anteriorly confluent with the external orbital angle; the second is more or less conical with a tip near its anterior end, its posterior slope being arched; the third bears a tip at its anterior end and generally arched at the outer border; near the posterior end of the third tooth a small fourth one is obscurely demarcated; the fourth teeth of both sides of the carapace are each indicated by a small granule. The postero-lateral border is weakly convergent and longer than the antero-lateral; it is dorsally covered with a pubescence and with the same small rounded granules as those on the antero-lateral dorsal surface. The posterior border is wide, rimmed along the whole length and weakly concave at the middle.
The chelipeds are approximately equal and alike each other except for the movable fingers, but the right is in reality slightly larger than the left. The merus is unarmed only with a crest of the upper border, which ends just at the subterminal notch. The greater surface of the carpus is naked and glabrous, but along the distal inner margin it is coarsely granulated with short, dense brush-like hairs; its inner angle is pronounced, tipped with a spiniform granule and fringed with a row of several long simple hairs along its inner slope. In the right chela the entire surface of the palm is smooth and naked, while in the left chela it is provided with some long hairs and rounded granules near the upper border. The movable finger is somewhat vertical due to the stout and rather short immovable finger; in the right chela both fingers are entirely naked, while in the left the proximal half of the movable finger and the base of the cutting edge and proximal end of the lower border of the immovable finger are coarsely granulated and hairy; in the left movable finger the middle part of the upper border is somewhat sunken; the cutting edges of both fingers are sharply and irregularly toothed; the blackish colour is restricted to the distal halves of the fingers in both chelae; the tips are strongly curved and crossed each other.
The ambulatory legs are long, but comparatively stout. The upper border of the merus is thin and very minutely serrated; it subterminal interruption is somewhat prominent. The upper border of the carpus is fringed with short setae and some long hairs, those setae becoming denser distally. The propodus is also fringed with short thick setae and long hairs along both borders. The dactylus is as long as each propodus and densely covered with short setae and long hairs; in the last pair the dactylus is weakly curved upward near the tip unlike those of the preceeding pairs. (Takeda & Miyake, 1969a)
Type locality: off Uze, Tomioka, Amakusa-shoto, Japan.
Range: Japan - Amakusa-shoto (Takeda & Miyake, 1969a).