Map of sampling locations for this study.

<p>A: Indian and Pacific Ocean, B: southern Red Sea, Gulf of Tadjoura and Gulf of Aden; C–E: main island of Japan and Ryukyu archipelago. AD: Aden, Yemen, AK: Akajima Island, Japan, AM: Amakusa, Japan, AO: Amami-Oshima, Japan, BA: Bir Ali, Yemen, BU: Al Mukallah, Yemen, DJ: Djibouti, IK: Iki Island, Japan, IR: Iriomote Island or Hatoma Island, Japan, IS: Ishigaki Island or Taketomi Island, Japan, KA: Kamaran Islands, Yemen, KK: Kikai Island, Japan KS: Kushimoto, Japan, MI: Miyako Island, Japan, MY: Mayotte Island, France, OT: Ootuki, Japan, OU: Oura bay, Japan, PEN: Song song Island, Malaysia, SO: Suou-Oshima, Japan, SR: Shirahama, Japan, SS: Sesoko Island, Japan, TN: Tanegashima Island, Japan, TR: Nakanoshima Island, Japan