Morphological taxonomy and molecular divergence of four balitorid species (subfamily: Nemachelinae) from Central Himalaya, India.

The fishes in this study belong to the difficult group. It is difficult to identify about more than 50 nemacheilid loach species in India, mainly due to the poor quality of the original descriptions, the lack of good reviews, and the similarity of a number of the banded species. In view of this, a morphometric and genetic study was conducted on four species that have been documented in Central Himalayan region of India. Using comparative methods, a contribution to the knowledge about the variability of four Himalayan hillstream loaches, a molted loach Acanthocobitis botia (Hamilton, 1822), Nemacheilus corica (Hamilton, 1822), a creek loach Schistura beavani (Gunther, 1868), and Schistura montana (McClelland, 1838), was accomplished. Morphometric data were analyzed by univariate (CV and analysis of variance) and multivariate analyses (discriminant function analysis and cluster analysis). Based on the results of these statistical analyses, generally all four species grouped into their own species cluster with minimal overlap between two species of genus Schistura. Mitochondrial DNA cytochrome b (Cyt b) gene analysis revealed 7.7-17.6% genetic distances among the four species. Molecular phylogenetic relationship among these species and other Balitoridae species was investigated using published mitochondrial Cyt b sequences. Dendrograms obtained by the maximum likelihood and maximum parsimony method analyses exhibited the same topology. According to this topology, all the four species represented distinct species group and A. botia form the most distinct species while S. beavani and S. montana are clustered together with Nemacheilus species to form a single group. This work may build the base for the revision of taxonomic identity of fishes of the family Balitoridae. The results may further help to enhance the knowledge of the ichthyologists in understanding the fish fauna of India and assist them in planning conservation and management strategies for the propagation of these less studied small indigenous species along their natural range of distribution.