A New Species of Macrophthalmus (Crustacea: Decapoda: Brachyura: Macrophthalmidae) from Iriomote Island, Ryukyu Islands, Japan

Abstract

A new species of the sentinel crab genus Macrophthalmus is described from Iriomote Island, southwestern Ryukyu Islands, Japan. Macrophthalmus ryukyuanus sp. nov. is referred to the M. telescopicus species group, within which it is morphologically most similar to M. milloti Crosnier, 1965. The forms of the eye, male chela, and fourth ambulatory leg clearly distinguish the new species from the latter. The new species is also compared to M. microfylacas Nagai, Watanabe and Naruse, 2006 and M. latipes Borradaile, 1903. A key to the Japanese species of the M. telescopicus group is provided.