Distribution of Trachinocephalus trachinus (Temminck & Schlegel, 1846) (Pisces: Aulopiformes: Synodontidae) Along the Arabian Sea and Bay of Bengal Coasts of India

Abstract

The genus Trachinocephalus (Aulopiformes: Synodontidae) was considered to be monotypic and nearly circumtropical in distribution, with single species, Trachinocephalus myops (Forster 1801). However, a revision indicated presence of at least three species under the genus – the Atlantic T. myops, the Indo-Pacific T. trachinus, a new species T. gauguini and later again a new species T. atrisignis added from Western Indian Ocean. Even though, two species are known from Indian Ocean, the species found in India is still being misidentified as T. myops. Thus, to confirm the species inhabiting in Indian waters, the samples were collected from multiple locations along the west (Arabian Sea) and east (Bay of Bengal) coasts of India. The recorded morpho-meristic characters were found to be substantially overlapping between T. myops and T. trachinus. Further, molecular analysis based on COI gene of mitochondrial DNA confirms the presence of more than four species in the world and the species distributed along the Indian coast as T. trachinus. The genetic distance estimated between T. trachinus and T. myops was found to be 16.9%, which is sufficient to separate the two species. Though, massive genetic divergence was observed, the species exhibited phenotypic stasis that can be the reason for misidentification. In recognition of the critical role of correct taxonomic identification in species conservation and management, an integrated taxonomic study was carried out on Trachinocephalus genus along the Indian coast.