First Japanese record of a deepwater snake eel, Ophichthus tomioi (Anguilliformes, Ophichthidae), from Wakayama, southern Japan

A single specimen of Ophichthus tomioi McCosker, 2010 (498.1 mm of total length, female) was collected during an ichthyofaunal survey of the rariphotic zone off Kushimoto, Wakayama, southern Japan. It has previously been reported only from deepwaters in the Philippines, Fiji, and the Marquesas Islands. Therefore, it represents the first record from Japanese waters and the northernmost record. Although the present specimen has 1+3 supraorbital pores on the right side (vs. 1+4 on both sides in type series of O. tomioi), it can be regarded as an abnormal condition based on its arrangement. Ophichthus tomioi is similar to Ophichthus aniptocheilos McCosker, 2010 and Ophichthus mystacinus McCosker, 1999 in the position of the opening of posterior nostril, the dark tip of anal fin, and the shape of pectoral fin. However, O. tomioi can be distinguished from O. aniptocheilos by the number of total vertebrae (166–189 vs. 140), and the number of mandibular tooth rows (2 vs. 1), and from O. mystacinus by the position of dorsal-fin origin (near pectoral-fin tip vs. about mid-trunk). The presence or absence of the pigmentation on the upper lip, which was previously included in the key characters for separating O. aniptocheilos from O. tomioi, should be regarded as unavailable.