A new species of the genus Hexapinus Manning & Holthuis, 1981 (Decapoda: Brachyura: Hexapodidae) from Okinawa Island, Ryukyu Islands, with a note on the heterogeneity of the genus

A new species of hexapodid crab of the genus Hexapinus Manning & Holthuis, 1981 is described based on three females from Okinawa Island, Ryukyu Islands, southwestern Japan. Hexapinus okinawa sp. nov., described in this study, can be distinguished from its closest congener, H. simplex Rahayu & Ng, 2014, by a narrower carapace and setation on the carapace and ambulatory legs. Molecular phylogenetic analyses also support the difference of these two species. In addition, close morphological examination and the molecular phylogeny indicate at least two linages are included within Hexapinus. The polyphyletic nature of Hexapinus and the characteristics of the two lineages are discussed.