Mitochondrial Genome of (Anura, Megophryidae, ): Insights into the Characteristics of the Mitogenome and the Phylogenetic Relationships of Megophryidae Species.

(Fang, 1985) is an endemic Chinese amphibian species within the genus (Megophryidae). Despite its ecological significance, its mitochondrial genome architecture and evolutionary relationships remain poorly understood. Given the high structural variability in Megophryidae mitogenomes and unresolved phylogenetic patterns in , this study aims to (1) characterize the complete mitogenome of , (2) analyze its molecular evolution, and (3) clarify its phylogenetic position and divergence history within Megophryidae. The complete mitochondrial genome was sequenced and annotated, followed by analyses of nucleotide composition, codon usage bias, and selection pressures (Ka/Ks ratios). Secondary structures of rRNAs and tRNAs were predicted, and phylogenetic relationships were reconstructed using maximum likelihood and Bayesian methods. Divergence times were estimated using molecular clock analysis. The mitogenome of is 17,282 bp long, encoding 13 protein-coding genes (PCGs), 22 tRNAs, 2 rRNAs, and a control region, with a notable AT bias (61.05%) with nucleotide compositions of T (32.51%), C (24.64%), G (14.3%), and A (28.54%). All tRNAs exhibited cloverleaf structures except trnS1, which lacked a DHU stem. Phylogenetic analysis confirmed the monophyly of , forming a sister clade to and , and that and are sister species with a close evolutionary relationship. Positive selection was detected in Atp8 (Ka/Ks > 1), suggesting adaptation to plateau environments, while other PCGs underwent purifying selection (Ka/Ks < 1). Divergence time estimation placed the origin of Megophryidae at47.97 MYA (Eocene), with diverging32.67 MYA (Oligocene). This study provides the first comprehensive mitogenomic characterization of , revealing its evolutionary adaptations and phylogenetic placement. The findings enhance our understanding of Megophryidae's diversification and offer a genomic foundation for future taxonomic and conservation studies.