First Japanese Record of Corythoichthys intestinalis (Teleostei: Syngnathidae) from the Ryukyu Islands

Abstract

Between 1992 and 2016, 11 specimens (31.1–112.8 mm standard length) of Corythoichthys intestinalis (Ramsay, 1881), collected from Amami-oshima island and Ie-jima island, Ryukyu Islands, southern Japan, were identified from the following combination of characters: superior trunk ridge discontinuous with superior tail ridge; lateral trunk ridge straight, ending near anal ring; inferior trunk ridge and tail ridges continuous; 15–16 trunk rings; 49–51 total rings; 26–30 dorsal-fin rays; posterior tail rings with prominent dark markings on dorsum; anal ring without a dark blotch ventrally; and dorsal fin without spots. The species was previously recorded from eastern Borneo to Samoa and Tonga but not from Japan. Hence, the present specimens represent the first Japanese and northernmost records of C. intestinalis. The new standard Japanese name, “Ryukyu-ishiyoji,” is proposed for the species.