2016 年 63 巻 2 号 p. 135-142
A taxonomic study of the speciose tropical/temperate water family Ophichthidae, revealed a single specimen of the snake eel, Phyllophichthus xenodontus Gosline, 1951 and three specimens of Muraenichthys sibogae Weber and de Beaufort, 1916 from the Ryukyu Islands, Japan. Descriptions of the two species based on the Japanese specimens are herein provided. The former, a monotypic species of the genus Phyllophichthus, is characterized by a prolonged and pointed snout, well developed eyes and broad anterior nostrils. The present species has been recorded from the Ryukyu Islands in the literature, but with no voucher specimens. The Ryukyu Islands voucher specimen therefore represents the first reliable record of the species from Japan based on the voucher specimen. Muraenichthys sibogae, is poorly known species elsewhere in the western-central Pacific Ocean, is recorded from Japan for the first time, bringing the number of Japanese representatives of the Indo-Pacific Ocean genus to three (also Muraenichthys hattae Jordan and Snyder, 1901 and Muraenichthys schultzei Bleeker, 1857). Although M. sibogae is similar to M. hattae in small head size [9.7–11% of total length (TL)], position of the dorsal-fin origin (slightly anterior to a vertical through mid anus), and high total vertebrae number (141–150), the former can be easily distinguished from the latter by its longer tail (63–67% TL vs. 56–62%) and a single row of teeth on the upper jaw (vs. 2 rows or more). The new Japanese standard names, “Gettoh-umihebi” and “Shirasu-mimizu-anago”, are proposed for P. xenodontus and M. sibogae, respectively.