A New Species of Apterichtus (Actinopterygii: Anguilliformes: Ophichthidae) from Tori-shima Island, Southern Japan with Notes on Characters of Supraorbital Canal

摘要

A new finless ophichthid eel, Apterichtus soyoae, is described based on a single specimen collected from off Tori-shima island, Zunan Islands of Izu Islands, southern Japan. The new species is similar to A. moseri and A. klazingai in its numbers of supratemporal pores, preopercular pores, and vertebrae. The new species differs from A. moseri in having more supraorbital pores (1+6 vs. 1+4), the number of branchings of the supraorbital canal (1 vs. 0), shape of the snout (distinctly pointed vs. relatively blunt), eye size (50% of snout length vs. 35-45%; 8.8% of head length vs. 6.3-8.0%), and the number of vomerine teeth (1 vs. 2-5). Apterichtus soyoae can also be distinguished from A. klazingai by the number of branchings of the supraorbital canal (1 vs. 2), the number of infraorbital pores (7 vs. 9), and the location of the lower jaw tip (anterior to a vertical through anterior margin of eye vs. posterior to the vertical). The number of supraorbital pores and branchings of the canal are discussed.