New distributional record of Atoportunus gustavi Ng & Takeda, 2003 (Decapoda: Brachyura: Portunidae) from Okinawa-jima and Ie-jima Islands, Ryukyu Islands, southwestern Japan

A rare portunid crab, Atoportunus gustavi Ng & Takeda, 2003 (Decapoda: Brachyura: Portunidae), is recorded from submarine caves in Okinawa-jima and Ie-jima Islands, Ryukyu Islands, southwestern Japan. This record represents the first discovery of A. gustavi from the islands and extends the geographical range of this species northward