First distribution record of Schistura scaturigina (Mcclelland, 1839), in the tons river, a tributary of the Yamuna river in Uttarakhand, India, by morphological and molecular approach

Abstract

The Tons River serves as a significant tributary of the Yamuna, traversing the Garhwal region of Uttarakhand. The river's cold, clear, and fast-flowing waters create an ideal environment for various cold-water fish species to thrive. Between 2019 and 2021, surveys documented fifteen specimens of Schistura scaturigina McClelland, 1839, belonging to the family Nemacheilidae, from various sections of the Tons River. Up to this point, this species has primarily been recognized from hill streams in Northeast India and a handful of adjacent areas. The recent findings from the Tons River broaden its recognized geographic range into the Garhwal Himalaya, suggesting a greater ecological adaptability than was previously acknowledged. To verify the species' identity, a combination of morphometric characteristics and molecular techniques was employed. The examination of mitochondrial DNA markers, particularly COI and 16S rRNA, aligned with the genetic profile of S. scaturigina, offering compelling evidence for its occurrence in this river for the first time. This finding enhances the species inventory of the Tons River and underscores the ecological significance of Himalayan tributaries in sustaining diverse fish communities. The results indicate a requirement for more comprehensive surveys to grasp the complete distribution and conservation requirements of this species.