沖縄県西表島から得られた日本初記録のウミヘビ科魚類マダラシマウミヘビ（新称）Myrichthys paleracio

抄録

Snake eels in the genus Myrichthys, characterized by molariform teeth, moderate to very elongate body, short snout, dorsal fin origin before gill openings, short pectoral fin, anterior nostrils tubular and elongate, posterior nostrils opening into mouth, and spotted and/or striped coloration, include 10 valid species and are commonly found along most tropical shores worldwide. Two species, Myrichthys colubrinus (Boddaert, 1781) [striped coloration] and Myrichthys maculosus (Cuvier, 1816) [spotted coloration], having been previously recorded from Japan, Myrichthys paleracio McCosker and Allen, 2012 is described here from two specimens found in the stomach contents of a sea snake Laticauda laticaudata (Linnaeus, 1758) from Iriomote Island, Okinawa Prefecture, Japan, being the first speciemen-supported record of the species from Japan and the northernmost record of distribution. Myrichthys paleracio most closely resembles M. colubrinus in having striped body coloration, but differs in having 183 total vertebrae (vs. 193–202) and more than 50 irregularly patterned brown stripes (vs. 25–35 arranged in a regular pattern). The absence of an ethmoid pore on the head in one specimen was considered to be a malformation. A new standard Japanese name “Madara-shima-umihebi” proposed for the species. An underwater photograph of a snake eel from Yakushima Island, Kagoshima Prefecture, Japan, was identified as M. paleracio.