A Distributional Review of the Genus Hydrovatus (Coleoptera: Dytiscidae) from the Ryukyus, Southwestern Japan

摘要

We revised the distribution list of Hydrovatus in the Ryukyus based on material deposited in museums, private collections, field surveys, and literature associated with previous records. New distributional records included: Hydrovatus acuminatus Motschulsky, 1859 from Tanega-shima Island (Is.), Akuseki-jima Is., Kikai-jima Is. and Hateruma-jima Is., H. remotus Bistrom et Watanabe, 2017 from Yonaguni-jima Is., H. stridulus Bistrom, 1997 from Tokuno-shima Is. and Iheya-jima Is., H. seminarius Motschulsky, 1859 from Kuchino-shima Is. and Nakano-shima Is., H.yagii Kitayama, Mori et Matsui, 1993 from Yonaguni-jima Is. (representing their southern limit). Further, we showed that all previous records of H. subtilis Sharp, 1882 from Iheya-jima Is. were H. stridulus. In addition, H. subtilis was not found among the specimens examined in this study. Therefore, we suggest that H. subtilis is not distributed in the Ryukyus, Japan.