Spider Crabs of the Genus Huenia De Haan, 1837 (Crustacea, Decapoda, Brachyura) from Japan, with Descriptions of Two New Species

Two new species of the genus Huenia De Haan, 1837 of the family Epialtidae (Majidae s.l.) are described from Japan under the names of H. nagaii and H. toyoshioae. A rare and poorly known species, H. pacifica Miers, 1879, is recorded from the Ryukyu Islands for the first time in Japanese waters. The Huenia species are sexually dimorphic and individually variable according to the developmental stages in the shape of the carapace, but both new species are differentiated from their eight congeners in the characteristic shape of the carapace.