Unveiling a New Puntius Species from the Brahmaputra Drainage and Its Genetic Connections with Related Species

During our survey of the Torsa River (Brahmaputra drainage) in West Bengal, India, we collected eight cyprinid specimens of the genus Puntius, which could not be assigned to any known species. We describe the specimen herein as, Puntius torsai. The new species is distinguished from its congeners by the following combination of characters: a complete lateral line with 24 pored scales; 9–10 pre-dorsal scales; 12 circumpeduncular scales; 5½/4½ lateral transverse scales; a total of 30 vertebrae; one pair of barbels; body depth of 41.25–45.33% standard length; head depth of 70.43–73.22% head length; the presence of a black horizontal band on the dorsal fin; a small humeral spot; and a caudal peduncle blotch covering the 20th–22nd lateral line scales. The evolutionary relationship of the Puntius torsai new species was confirmed based on the cytochrome oxidase I (COI) gene sequence. Maximum likelihood phylogenetic analysis for 81 COI sequences of Puntius sensu lato revealed its placement within the genus Puntius sensu stricto. The K2P genetic distance with all other Puntius sensu stricto species ranged from 5.4–13.4%, confirming its distinct identity. The Bayesian Poisson Tree Processes species delimitation algorithms also supported the unique identity of Puntius torsai within Puntius sensu stricto. A thorough integrative taxonomic approach is essential to uncover the cryptic diversity within Puntius, which is crucial for improved fisheries management and biodiversity conservation.