Sakai, 1935
This species is closely related to Ceratoplax granulosa McGilchrist from the Gulf of Martaban, but it is characterized by the following particulars:
1. Carapace pubescent, nearly flat from side to side, vaulted downwards anteriorly so as to conceal the edge of the front in dorsal view. The regions of the carapace are fairly so well delimited but to the naked eye it appears not so distinctly granulated as in C. granulosa.
2. The antero-lateral borders are crested and arcuated, indistinctly four-lobed by three shallow notches, the last two lobes are narrower and show tendency to unite with each other, the carapace showing here the maximum breadth. The postero-lateral borders are convergent and slightly concave, with very fine granules; the free edge covers the bases of the ambulatory legs and is finely spinulated.
3. The front is very strongly bent down, bilobed and is furnished with long hairs. In C. granulosa the proportion of breadth to length of the carapace is more than 1.33, while in the new species it is less than 1.25, the carapace being apparently longer than in the former.
4. The eyestalk fixed, fringed with hair; cornea ventral and pigmented. Buccal cavity anteriorly broadened, rounded at the anterior corner. The antero-external angle of the merus of the external maxilliped strongly produced.
5. In C. granulosa, the first two abdominal segments are described to be very short, the first being very broad but not reaching the bases of the last ambulatory legs. In the new species, the first abdominal segment is very short but very much broader than in granulosa, fairly well reaching the bases of the last ambulatory legs. The second segment is not very short, the terminal segment longish triangular.
6. The chelipeds massive, not very much unequal. Merus has a very sharp upper ridge and is armed with an indistinct sub-distal tooth; the inner angle of the carpus is produced to form a distinct tooth. These two segments are, in C. granulosa, covered with vesticular granules, but in the new species, the granules are rudimentary, except those fine ones on the margins observable under the lens. Propodus very broad, with four or five longitudinal rows of sharp granules, the regular arrangement of which hardly reaches the middle of the palm, where the surface is smooth and polished toward the distal end of the cheliped. In granulosa, the outer surface of the palm is covered thickly and irregularly with sharp vesicular granules.
The fingers are lightly pigmented in the distal half, the prehensile edges are furnished with a few triangular teeth; the tips cross each other when they are closed.
7. The ambulatory legs are fringed with long hairs, thickly on the anterior border but sparsely on the posterior border. The first and fourth pairs sub-equal, and so the second and third pairs, though they are distinctly longer than the former. The dactyli of the first three pairs are sub-equal in length and are straight; that of the last pair short and upwardly curved. Coxa of each pair is dorsally provided with a process, which terminates in 4 or 5 pectinated processes. (Sakai, 1935)
Type locality: Fukuura and Manazuru-saki, west of Sagami Bay, Japan.
Range: Japan - Fukuura and Manazuru-saki, west of Sagami Bay (Sakai, 1935, 1939), Sagami Bay (Sakai, 1965b), Sagami Bay and Tosa Bay (Sakai, 1976a); 75-95 m.