Characterization and Phylogenetic Analysis of the Complete Mitochondrial Genome of Triplophysa microphthalma

The complete mitochondrial genome has been extensively utilized in studies related to phylogenetics, offering valuable perspectives on evolutionary relationships. The mitochondrial genome of the fine-eyed plateau loach, Triplophysa microphthalma, has not attracted much attention, although this species is endemic to China. In this study, we characterized the mitochondrial genome of T. microphthalma and reassessed the classification status of its genus. The complete mitochondrial genome of T. microphthalma was 16,591 bp and contained thirty-seven genes, including thirteen protein-coding genes (PCGs), two ribosomal RNA genes (rRNAs), and twenty-two transfer RNA genes (tRNAs). All but one of the thirteen PCGs had the regular start codon ATG; the gene cox1 started with GTG. Six PCGs had incomplete stop codons (T--). These thirteen PCGs are thought to have evolved under purifying selection, and the mitogenome shared a high degree of similarity with the genomes of species within the genus Leptobotia. All tRNA genes exhibited the standard clover-shaped structure, with the exception of the trnS1 gene, which lacked a DHU stem. A phylogenetic analysis indicated that T. microphthalma was more closely related to species within the genus Triplophysa than to those in Barbatula. The present study contributes valuable genomic information for T. microphthalma, and offers new perspectives on the phylogenetic relationships among species of Triplophysa and Barbatula. The findings also provide essential data that can inform the management and conservation strategies for T. microphthalma and other species of Triplophysa and Barbatula.