Cytochrome b gene sequence divergence of seven sisorid species of catfish genus Glyptothorax (siluriformes, sisoridae) from India.

Samples of seven Sisorid catfish species of the genus Glyptothorax (G. garhwali, G. dakpathari, G. brevipinnis, G. ngapang, G. granulus, G. ventrolineatus, and G. davissinghi) were collected from the Himalayan region and the Western Ghats of India. They were analyzed for the mitochondrial cytochrome b gene (Cyt b). Out of 1152 nucleotide positions analyzed, 269 (23.3%) were found to be variable and 235 (20.3%) were parsimoniously informative. The sequences showed 111 (9.6%) fourfold degenerate sites. The overall transition/transversion bias was R = 3.457. The average proportion of base substitutions measured as P-distance for all sequences of seven Glyptothorax species and other five species comprising four comparison groups was intraspecies, P = 0.17 ± 0.05%, intragenus, P = 10.75 ± 0.48%, intrafamily, P = 20.07 ± 1.43%, and intraorder, P = 21.10 ± 0.45%. Within the Glyptothorax genus maximum divergence was obtained among G. brevipinnis sequences, whereas the least divergence was obtained within G. davissinghi. The phylogenetic trees for 193 and 47 sequences of Sisorid catfishes together were developed using the Cyt b gene and four different analytical approaches: Bayesian (BA), neighbour-joining (NJ), maximum parsimony (MP), and maximum likelihood (ML). The analysis revealed a monophyletic origin for the all investigated representatives of the genus Glyptothorax (99, 100, 99, and 73% support level in our BA, NJ, MP, and ML analyses respectively) and with some reservations for Sisoridae, which is the principal family investigated. The monophyletic origin of the two subfamilies of Sisorid catfish defined in the literature was partly also supported by molecular phylogenetic data.