Sakai, 1965
The new species, which was formerly misidentified as Acmaeopleura balssi, can be distinguished from A. balssi in the following particulars:
1. The carapace of the new species is more broad than long, the ratio between the length and width being 1 : 1.3, while, in Acmaeopleura balssi, it is proportionally narrower, the ratio between the two being 1 : 1.2. The dorsal surface is depressed, thickly punctate and microscopically granulated; in A. balssi, it is moderately convex and smooth or rather glabrous, and is only sparingly punctate. In both species, the carapace is broadest in the middle portion of the antero-lateral borders.
2. The frontal margin is finely granulated, almost straight and not emarginated medially, its breadth much less than one third the breadth of the carapace; in Acmaeopleura balssi, it is about one third the breadth of the carapace, and medially emarginated.
3. The postero-lateral borders of the present species are moderately convergent, by which the epimerons are completely covered and cannot be detected in dorsal view; in A. balssi, the postero-lateral borders are well defined, below which the epimeron can be detected in dorsal view.
4. The ambulatory legs are found rather short and robust, when compared with those of A. balssi, and the meri are cristate along the anterior border.
Our regret is that no male specimens have been comprised in His Majesty's collection, and that no inquiries have ever been made into the sub-orbital crests and the pleopods. (T. Sakai, 1965: 196)
Type locality: Sagami Bay, Japan.
Range: Japan - Shimoda (Sakai, 1939), Sagami Bay (Sakai, 1965b, 1976), Matsuyama, Seto Inland Sea (Takeda et al., 2000).