DNA barcoding reveals a new species of deepwater catshark of the genus Apristurus (Chondrichthyes: Pentanchidae) from India, in the Southeastern Arabian Sea

This article provides a description of a new species of a catshark of the family Pentanchidae, Apristurus drona sp. nov. based on 4 specimens, which include two males and two females ranging from 439–473 mm TL, collected off the Kollam slope, Southwest coast of India, at a depth of 400– 650 m. This new species is placed in the Apristurus brunneus subgroup among the three groups divided within the genus Apristurus and is characterized by the following features: slender body, tapering posteriorly; nostril length is smaller than internarial width; pre-outer nostril length shorter than interorbital space; pre-outer nostril length 3.7(3.5–5.2) % TL; pre-oral length shorter than the mouth width, 33.6(31.7–34.0)% head length and 8.1(7.1–8.1)% TL; nostril-mouth space shorter than nostril length, about 0.4 (0.3–0.4) times; upper labial furrows longer than the lowers furrows; internarial width slightly greater than or equal to orbit length, about 1.09(1.0–1.11) times; 5 th gill slit height smallest, about 46.8(46.8–62.5)% eye length; Inter-dorsal space 9.3(8.8–10.5) % TL; first dorsal fin smaller than the second dorsal fin; first dorsal fin insertion is opposite to anal fin origin; anal fin base length is greater than pectoral-pelvic space and pelvic-anal space; pectoral to pelvic space greater than pelvic to anal space; spiral valve turns 11–12; total vertebrae 105–115.

Apristurus drona sp. nov. is also distinguished from its congeners based on DNA sequence divergence of the COI gene. This new species has a distribution along the Kollam slope, Arabian Sea, whereas its three closest congeners, based on a molecular level, are from distant locations: A. nayakai from Southwestern Pacific Ocean, A. macrorhynchus from Northwest Pacific and A. exsanguis from New Zealand.