A new species of eight-gilled hagfish (Myxinidae: Eptatretus) from the deep waters of the Lakshadweep Sea, India

Abstract

A new species of eight-gilled hagfish genus Eptatretus (Myxinidae) is described based on five specimens trawled on the upper continental slope off Kollam, Kerala, India, northern Indian Ocean. Eptatretus gopali sp. nov. can be diagnosed by the presence of eight-gill pouches and gill apertures, 10–11 pre-brachial, 7 branchial, 50–55 trunk, 9–10 tail slime pores, 77–82 total pores, 3/2 multicusp teeth pattern, 40–44 total cusps, absence of nasal-sinus papillae, and a light brown body color. Detailed morphological comparisons with all known eight-gilled species of Eptatretus showed that the new species was distinct from all others by having 40–44 total cusps, characteristic body proportions, and the shortest tail length. E. gopali formed a district clade in the phylogenetic tree and exhibited a genetic distance of 3.6%–11.6% in Cytochrome C oxidase I (COI) sequences and 2.0%–4.9% in 16S rRNA sequences between the congeners. An identification key is also provided for the species of Eptatretus from the Indian Ocean.