Genus Lima Bruguière, 1797

Lima sp. indet.

Figures 221-227

The present species is represented by a few specimens from the bottom sediment of "Cross Hole" (RM19487, including a living individual), "Fool's Palace" (RM19485) and "Black Hole" (RM19486) of Shimoji-Irabu Islet, Miyako Islands, and a few dead specimens (RM19488) from "Shodokutsu" of Ie Islet, Okinawa.

It is characterized by small size (less than 3.5 mm in height), about 25 simple radial ribs with sparsely and quincuncially disposed small scales, very anteriorly located umbo, large posterior auricle, narrow, prosoclinal and curved ligament pit, and one or two incipient teeth on the anterior and posterior parts of the hinge plate. The outline and ornamentation strongly remind us of those of Lima (s. s.), but the anteriorly located umbo, large posterior auricle and narrowly curved ligament pit are similar to those of some species of Acesta. Moreover, unlike many shallow-water limids, the present species has large Pd I (about 260 µm in maximum diameter) and no Pd II.

These specimens seem to belong to a new species, but it is still uncertain whether the material contains adult individuals or not. The distribution pattern of scales on the external surface is essentially similar to that of Lima tomlini Prashad, 1932, from the lower sublittoral and bathyal depths in Indonesia, the Philippines and southern Japan, but the radial ribs are decidedly fewer, the posterior auricle is larger and the shell size is much smaller in the present species.