Sakai, 1963
Although the single male type specimen is rather young, it does not agree with other species of the genus Heteronucia already described from the Indo-Pacific, and it is designated as a new species. The carapace is as long as broad, somewhat rhomboidal in outline, the dorsal surface is convex, with vesicular tubercles, of which those found near the lateral and posterior borders are very high with a knobbed tip. The gastric region is ill-defined, but the mesogastric area is indicated by a pair of granulated tubercles. The cardiac region is convex, circular in outline. The front is well produced forward, the anterior margin of each lobe is thick and closely covered with rather flat granules. The supraorbital margin has pre- and supraorbital fissures. The hepatic region is moderately convex and the branchial border is quite swollen. These two borders are armed with long, curved spine-shaped tubercles, their tips being knobbed as already described. The posterior border is nearly as wide as the front, with a rounded lobule on either side.
The antennular fossae are just like those of Heteronucia venusta Nobili (1906), the common Indo-Pacific species, but their outer edge does not touch the inner, inferior orbital lobe, thus the hiatus between the two is loosely filled by the basal segment of the antenna, the flagellum of which is composed of four segments, and is apparently longer than that of H. venusta.
The chelipeds are rather slender, the merus, carpus and propodus are thickly covered with low conical tubercles, most of which are arranged in longitudinal rows. The fingers are a little shorer than the palm.
The ambulatory legs are also rather slender, the tubercles on each segment are conical, arranged in longitudinal rows. The dactylus is as long as the propodus and very slender.
The abdomen is sparingly covered with flat granules; the third to fifth segments are fused together.
Measurements: Male holotype, length of carapace, measured in the median line, 3.3 mm, width of same 3.5 mm. (T. Sakai, 1963)
Type locality: Manazuru, Sagami Bay, Japan, 80 m.
Range: Japan - Sagami Bay (Sakai, 1963, 1965, 1976), Tosa Bay (Sakai, 1976a); 65-80 m.