Redescription of an endemic mahseer, Tor mahanadicus (David, 1953) from Mahanadi River basin, India based on integrated morphological and molecular techniques.

Abstract

Tor mahanadicus was originally described as Tor mosal mahanadicus with inadequate information on its morphological traits and no designated type specimen. Currently, T. mahanadicus is synonymized with Tor putitora, solely based on partial molecular data despite significant morphological differences. In this study, we performed an integrated morphological and molecular analysis to redescribe T. mahanadicus from the Mahanadi River. Tor mahanadicus is distinguished from all known Indian Tor species by the presence of 2 complete rows of scales between pelvic fin origin and lateral line, small eye (15.3-16.9% in head length), and a wide mouth gap (21.7-23.8% in head length). Moreover, it undoubtedly distinguished from the closely related species Tor putitora by having a wider body depth (26.8-28.2% in standard length vs. 14.5-19.9%), short snout length (23.3-26.4% in head length vs. 28.0-29.3%) and wide inter orbit space (30.5-37.3% in head length vs. 27.6-28.5%). Additionally, the molecular phylogenetic tree generated from a combination of three genes demonstrates a monophyletic clade separate from the Tor putitora clade. Based on the distinct morphological traits and mitochondrial gene sequences, we established Tor mahanadicus as separate species under the genus Tor.