Morphological and Molecular Delineation of Opsarius bendelisis Across the South Asia
摘要
Species identification and delineation are crucial for evolutionary, ecological, and conservation research, yet challenges persist in accurately defining species boundaries. The Indian Hill Trout, Opsarius bendelisis, inhabits fast-flowing streams across the Indian subcontinent and holds ecological and economic significance. This study integrates morphological and molecular approaches to assess the intraspecific variability and phylogenetic assessment, species delimitation and biogeographic distribution of O. bendelisis across diverse riverine systems. Morphometric analyses of 38 specimens from five Indian river (Siang, Torsa, Teesta, Tapti, and Cauvery) were conducted, complemented by the examination of 160 mitochondrial cytochrome c oxidase subunit I (COI) gene sequences from India, Nepal, and Bangladesh. Morphometric and meristic analyses revealed no significant variation in traditional taxonomic traits among geographically distant populations. However, size-adjusted MANOVA and PCA indicated significant population-level differences, likely influenced by geographic and environmental factors. Molecular analysis showed less than 2% genetic divergence among O. bendelisis specimens from India (Cauvery, Pennar, Sabarmati, Narmada, Brahmaputra, Ganga, Chenab), Nepal (Karnali, Begans Lake), and Bangladesh (Brahmaputra, Surma-Meghna, Sangu, Karnaphuli), confirming their genetic coherence. Maximum Likelihood phylogenetic analysis demonstrated a monophyletic clade for O. bendelisis, distinguishing it from other Bariliine species. Species delimitation analysis (ABGD and bPTP) consistently identified a single Molecular Operational Taxonomic Unit, reinforcing species uniformity. The findings provide valuable insights into the taxonomic status and biogeographic distribution of O. bendelisis, contributing to its conservation and management.