One New and Two Rare Species of the Genus Pilumnus Leach, 1816 (Crustacea: Decapoda: Brachyura: Pilumnidae) from Takase Submarine Bank off the Izu Islands, South of Tokyo, Japan

抄録

One new and two rare crab species of the genus Pilumnus Leach, 1816 are reported from Takase submarine bank off the Izu Islands, south of Tokyo, Japan. The new species, P. okutanii, is characteristic in the glabrous carapace, with a vestigial third anterolateral tooth, and the heavily spinose chelipeds and ambulatory legs. The other two species, P. curvipenis Komai and Motoh, 2012 and P. orbitospinis Rathbun, 1911, are also newly recorded from Takase submarine bank. Pilumnus curvipenis is a small species having the heavily spinose chelipeds and ambulatory legs which are similar to those of the new species, but different from it in the carapace dorsal surface roughened with granules and the carapace anterolateral margin armed with three strong teeth. Pilumnus orbitospinis is readily distinguished from the other congeneric species by having a prominent spine at the inner angle of the infraorbital margin.