Two Estuarine hermit Crab Species of the Genus Clibanarius (Crustacea: Decapoda: Diogenidae) from the Ryukyu Islands, Southern Japan

Two estuarine species of the hermit crab genus Clibanarius are recorded for the first time from the Ryukyu Islands, southern Japan. The occurrence of Clibanarius demani Buitendijk, 1937 in Okinawa Island represents a new addition to the Japanese fauna and greatly extends its distributional range to the northeast. Clibanarius infraspinatus (Hilgendorf, 1869) is broadly distributed in the Indo-West Pacific including the mainland of Japan, but there have been no definite records from the Ryukyu Islands until the present report. A brief note on the species of Clibanarius recorded from the Ryukyu Islands is provided, along with a key to these species.