Complete Mitochondrial Genome of Chlorogomphus papilio (Odonata: Anisoptera: Chlorogomphidae) and Phylogenetic Analyses

This study aimed to elucidate the mitochondrial genome organization of <i>Chlorogomphus papilio</i> and the phylogenetic relationships of Chlorogomphidae. We used the Illumina MiSeq sequencing platform to sequence the mitochondrial genome of <i>C. papilio</i>, which was subsequently assembled, annotated, and analyzed. Bayesian inference, maximum likelihood, and maximum parsimony methods were employed to construct the mitochondrial phylogenetic tree of 25 species of Chlorogomphidae based on <i>16S rRNA</i> and <i>cox1</i> genes. We observed that the mitochondrial genome of <i>C. papilio</i> is 15,251 bp in length and includes 13 protein-coding genes (PCGs), 22 tRNA genes, 2 rRNA genes, and a non-coding control region. All PCGs start with a typical ATN codon. While <i>cox1</i>, <i>cox2</i>, <i>cox3</i>, and <i>nad5</i> end with an incomplete termination codon (T), the remaining PCGs terminate with TAG. The secondary structure of the 22 tRNAs showed that only the <i>trnS1</i> gene lacked the dihydrouracil arm (DHU arm), whereas the rest formed a typical cloverleaf structure. Additionally, 32 G-U mismatches were observed in the secondary structure. Phylogenetic analyses indicated that <i>C. papilio</i> and <i>C. magnificus</i> are sister species. Divergence time analyses indicated that Chlorogomphidae originated around 111.04 Ma, with <i>C. papilio</i> diverging from the common ancestor shared with <i>C. magnificus</i> approximately 58.51 Ma. This divergence is likely linked to the Paleocene-Eocene Thermal Maximum (PETM) and the tectonic uplift of the Himalayas, which created warm, humid habitats and contributed to geographic isolation. This study contributes to a better understanding of the mitochondrial genome and phylogeny of <i>C. papilio</i>, providing valuable molecular markers for further genetic studies.