Decoding the Mitogenome of Takydromus intermedius: Insights into the Comparative Mitogenomics and Phylogenetic Relationships of Takydromus Lizards

The genus Takydromus (grass lizards) represents a diverse and ecologically significant group of lacertid lizards widely distributed across East and Southeast Asia. However, phylogenetic relationships within the genus remain contentious, primarily due to limited molecular data and inconsistent results from previous studies based on single or few mitochondrial genes. This study aimed to (1) sequence and characterize the complete mitogenome of T. intermedius; (2) perform a comparative analysis of mitogenomic features across the genus; and (3) reconstruct a robust phylogeny to clarify intra-generic evolutionary relationships. The mitogenome of T. intermedius was 18,770 bp in size and contained the typical set of 37 genes. Comparative analyses revealed characteristic features including AT-richness, strand asymmetry, and considerable length variation in the control region attributable to tandem repeats. The ATP8 gene showed the highest nucleotide diversity, and all protein-coding genes were found to be under strong purifying selection. Phylogenetic trees were reconstructed from a concatenated dataset of 13 protein-coding genes and two rRNA genes using both maximum likelihood and Bayesian inference methods. The resulting phylogeny strongly supported the monophyly of Takydromus and resolved several species relationships; however, it did not support the recognition of Platyplacopus as a distinct subgenus. Moreover, our mitogenomic analysis strongly validates the forest-grassland ecological speciation hypothesis and the southern–northern lineage division in Takydromus. Our study provides valuable mitogenomic resources and underscores the utility of complete mitochondrial genomes in elucidating phylogenetic relationships within Takydromus. These findings lay a solid foundation for future taxonomic and evolutionary studies, although expanded species sampling is needed to fully understand the genus’s diversification history.