The phylogenetic status of Pseudocheneis sulcata (Siluriformes: Sisoridae), a less-studied sucker-throat catfish, remains unresolved due to limited molecular evidence. This research explores its genetic relationships through mitochondrial Cytochrome c oxidase I (COI) sequences. A total of 46 Sisoridae species, representing two subfamilies (Glyptosterninae and Sisorinae), were retrieved from the NCBI database through nucleotide BLAST searches, along with three newly generated sequences collected from natural habitats. Pairwise genetic distances were calculated, and a Neighbour-Joining (NJ) tree was constructed to evaluate divergence among species. Phylogenetic relationships were further analysed using Maximum Likelihood (ML) methods based on the best-fitting nucleotide substitution model. The resulting phylogenetic tree delineated several well-supported clades aligned with recognised taxonomic groups within Sisoridae. P. sulcata consistently nested within the Sisorinae lineage, forming a distinct clade closely related to some Glyptothorax species, indicating a shared ancestry and possible taxonomic revisions. Estimates of Genetic distance underscore intergenic divergence, while revealing relatively lower divergence between P. sulcata and its closest congeners. These findings provide the first molecular insight into the phylogenetic position of P. sulcata, contributing to a deeper understanding of evolutionary relationships within Sisoridae. And highlights the utility of COI-based analyses in resolving systematics of Sisoridae, with implications for biodiversity assessment and conservation planning.
Keywords: Pseudochenesis sulcata, Sisoridae, Cytochrome c oxidase I (COI), molecular phylogenetics, genetic distance, freshwater catfish.