(Lockington, 1877)
The entire animal is covered with short hairs, but in full-grown specimens, the carapace and chelipeds are naked and their surfaces glossy. The carapace is pyriform, rounded in its posterior half and narrowed in its anterior half. The rostrum is projecting into a single process and its tip rounded.
The gastric region is convex, marked with a tubercle of a good size in the middle portion, around which several smaller tubercles are found. This median large tubercle is sometimes divided into two. The cardiac region is also convex, marked with a large tubercle in the middle portion, around which a few smaller tubercles are found. The intestinal region is not much convex, with a large tubercle in its posterior portion. In the female, this intestinal tubercle is usually wanting. The hepatic region is small, no dorsal tubercles besides a few tiny ones; its lateral margin is marked with three or four tubercles, anterior one of which is a little larger. The branchial region is dorsally marked with about 30 tubercles, on the upper inner surface, the tubercles form a group forming obscurely oblique rows. The margin of this region is marked with a series of eight or nine tubercles, three or four of which are larger. The number and arrangement of the tubercles on these regions are individually variable. No specific differences between Japanese and California specimens can be seen in regard to the feature of carapace as well as in the number and arrangement of tubercles.
The supraorbital eave is well defined, marked with a tubercle of a good size at its anterior end; this large tubercle is obliterated in female or younger specimens. The basal antennal segment is armed with a strong tooth at its antero-external angle, the form and size of this tooth are almost the same in both Japanese and California forms.
The male abdomen is consisted of six segments, the penultimate and terminal segments being fused together. The female abdomen is consisted of five segments, the fifth to seventh segments being fused together. According to Dr. Garth, the male abdomen of Japanese form is narrower and its lateral borders concave, but in most of the specimens before the author, such features are not so remarkable. The female abdomen is more thickly covered with tubercles than in the male.
The form of apex of the anterior male pleopod is rather complicated, the outlet of the spermatophore being encircled with thin membrane and edged wall on both outer and inner margins. The appendage of the California specimen was already drawn by Garth (1958 1. c., pl. E, fig. 7). In his figure, however, such thin membrane and edged wall were overlooked. In regard to the form of the anterior pleopod of male, Japanese specimens seem to differ from California forms, while, that of the male from California sent by Dr. Garth is almost agreeing with that of the Japanese specimen, as shown in Text-fig. 3 a, b. The discrepancy seen between Garth's figure and those of the present author probably due to the difference of angle when the pleopod was examined by microscope, and also partly to the difference of growth (?). It is wonderful that the pleopod of Erileptus spinosus Rathbun, figured by Garth in his Pl. E, fig. 8 (loc. cit.) is somewhat resembling that of P. tuberculata from Japan and also from California figured in the present opportunity.
The chelipeds are robust. The merus and carpus are marked with a few tubercles on the inner and outer borders. The propodus is thick and its surface smooth; there are a few tubercles, which are arranged in a median longitudinal row on the outer proximal surface, and also a few others near the proximal outer and inner surfaces. The prehensile edges of both fingers are finely denticulated, one or two proximal teeth are a little larger than the others.
The ambulatory legs are slender, the first pair is the longest, nearly thrice the entire length of carapace; the last pair is the shortest, half as long as the first pair. The main segments of these legs are distally thickened; no distal or proximal spines or teeth on each segment. The posterior edge of the dactylus is armed with ten to twelve denticles, but in full-grown specimens, these denticles are obliterated. (Sakai, 1971: 144)
Type locality: San Diego Bay, California.
Range: Japan - Sagami Bay and Tokyo Bay (Sakai, 1971), Tokyo Bay, Miura Peninsula, Sagami Bay and Yokkaichi (Sakai, 1976a), Osaka Bay, Seto-naikai; Western Australia - Cockburn Sound, south of Perth (Morgan, 1990); from California to Bay of Panama - San Diego Bay (Lockington, 1877), Lower California (Rathbun, 1894c), Gulf of California (Rathbun, 1894c).