Macrophthalmus ( Macrophthalmus ) microfylacas , a new species of sentinel crab (Decapoda: Brachyura: Ocypodidae) from western Japan

A new species of the Macrophthalmus telescopicus complex is described from Japan. The new species is closely allied to M. telescopicus (Owen, 1839), M. milloti Crosnier, 1965, and M. serenei Takeda & Komai, 1991. Macrophthalmus microfylacas sp. nov., however, is distinguished from these three species by the shape of the second and third anterolateral teeth, the shape of the gap between the first and second teeth, and a small body size. The new species can also be differentiated from M. milloti and M. serenei by the shape of the subproximal tooth of the male cheliped dactylus, while it differs from M. telescopicus by the shape of the G1.