First Japanese record of Gymnothorax pseudoprolatus (Anguilliformes: Muraenidae) from the west coast of Satsuma Peninsula, Kagoshima Prefecture

Abstract

A single specimen [411.5 mm total length (TL)] of the Short-tail Brown Moray Gymnothorax pseudoprolatus Smith, Hibino and Ho, 2018 was collected at a depth of 27 m off Kasasa, Minami-satsuma, Kagoshima Prefecture, Japan. The specimen possessed the following characters: 75 pre-anal vertebrae; 175 total vertebrae; maxillary teeth biserial anteriorly and uniserial posteriorly; dentary teeth uniserial; 6 mandibular pores; head length (HL) 11.1% of TL; pre-dorsal length 8.6% of TL; body depth at gill opening 4.1% of TL; body uniformly brown; and lips whitish. Although G. pseudoprolatus is most similar to Gymnothorax prolatus Sasaki and Amaoka, 1991, it differs from the latter in having a longer pre-anal region (pre-anal length 50.0–53.6% of TL vs. 48–51% in G. prolatus), shorter snout (snout length 17.8–20.7% of HL vs. 20.0–23.8%), 6 mandibular pores (vs. 7), 75–78 pre-anal vertebrae (vs. 79–83), and 169–175 total vertebrae (vs. 182–187). In addition, analysis of the mitochondrial cytochrome oxidase I (COI) gene of both species showed them to be separated by 3.2–3.8% average sequence divergence. Gymnothorax pseudoprolatus has been previously known only from the holotype from Taiwan. Therefore the Kagoshima specimen represents the first record from Japanese waters and the northernmost record for the species. The new standard Japanese name “Chairo-utsubo” is proposed for the species.