(Sakai, 1963)
This new species is apparently the largest of all the known species of this genus: its dorsal surface is extremely convex, with eight protuberances, of which the protogastric ones are so large and markedly swollen that the frontal region is mostly concealed by them in dorsal aspect. The outer branchial protuberances are also markedly convex, but the inner branchial ones are a little less convex; the metagastric and cardiac regions are rather low and depressed, the surfaces outside of these regions are extremely depressed. The intestinal region is fairly well demarcated and convex. The surfaces of these protuberances are sparingly pitted.
The front is thick, obtusely bilobed. The antero-lateral and postero-lateral borders are continuous, cut into eight lobes, each of which is carinated near the middle but there are no suture lines between the lobes. The posterior border is markedly broader than the front, its free edge is thick and medially concave.
The third maxillipeds perfectly close the buccal cavern, the merus and ischium are thickly covered with coarse tubercles; the former is markedly shorter than the latter and its anterior extremity divided into two processes. The outer process is more prominent than in Sakaila imperialis and is apparently bifid and fitted to the deep efferent branchial orifice, while the inner one is low and rather transverse, and its anterior edge is fitted against the median transverse ridge of the anterior buccal frame between the two efferent branchial orifices.
The chelipeds are robust, each segment is thickly covered with coarse tubercles, which are asteroidal in shape and arranged to form a network. The merus is flattish prismatic in shape, its inner surface is flat, its superior ridge is armed with five or six teeth, the last one of which is large and subterminal, and its lower edge is cut into three erect spines. The carpus is convex on the outer surface, its antero-internal angle is produced into a sharp tooth, whence a serrated ridge runs toward the inner surface. The propodus is very high, its upper ridge is sharp and armed with three teeth, the lower edge is armed with four sharp spines. The upper margin of the movable finger is also sharp and armed with four or five spines, the lower margin of the immovable finger is also armed with four or five spines. The prehensile edge of both fingers is cut into five or six low triangular teeth.
The ambulatory legs gradually decrease in size from the first to the fourth pair, the anterior border of the merus is cristate, and armed with a terminal and a subterminal tooth. The upper and lower posterior borders are also cristate, the former is irregularly serrated. The carpus and propodus of each pair are roughly covered with tiny tubercles, some of which are developed into spinules; the anterior and posterior borders are armed with several sharp spines.
The abdomen is thickly covered with tiny tubercles, most of which form small groups or networks.
Measurements: Female holotype, length of carapace 39 mm, width of same 51 mm. (T. Sakai, 1963)
Type locality: Sakaihama, Kii Minabe, Japan.
Range: Japan - Kii Minabe and Tosa Bay (Sakai, 1963, 1965, 1976), Kii Susami (Miyake, 1983); 35-75 m.