Characterization and Phylogenetic Analysis of the Complete Mitochondrial Genome of Celaenorrhinus victor (Lepidoptera: Hesperiidae)

Background: Skipper butterflies (Hesperiidae) are a morphologically distinctive lineage within Papilionoidea, yet relationships among many groups remain difficult to resolve, and mitochondrial genomic resources remain limited for some tribes, including Celaenorrhinini. Methods: We sequenced and characterized the complete mitochondrial genome of Celaenorrhinus victor using Illumina short-read sequencing. Gene content and organization were annotated, codon-usage patterns were assessed across Celaenorrhinus using relative synonymous codon usage and multiple compositional/selection tests (ENC–GC3s, neutrality, and PR2 analyses), selective constraints were evaluated using Ka/Ks for 13 protein-coding genes, and phylogenetic relationships were inferred with a partitioned maximum-likelihood analysis of 66 complete hesperiid mitogenomes. Results: The circular mitogenome of C. victor is 15,180 bp and contains the typical 37 genes (13 protein-coding genes, 22 tRNAs, and two rRNAs) plus an A + T-rich control region, with an overall A + T content of 79.64%. Gene order and orientation match those of other Celaenorrhinus and hesperiid mitogenomes. All protein-coding genes use standard invertebrate mitochondrial start codons (with cox1 initiating with TTG) and terminate with complete TAA stop codons. Codon usage is strongly biased toward A/U-ending codons and is broadly similar among five sampled Celaenorrhinus mitogenomes; ENC–GC3s, neutrality, and PR2 analyses indicate a predominant influence of A + T-directed mutational pressure with additional effects beyond base composition. Ka/Ks values for all 13 protein-coding genes were <1, consistent with pervasive purifying selection; cox genes were the most conserved, whereas several NADH dehydrogenase subunit genes evolved comparatively faster. The phylogeny recovered monophyletic Celaenorrhinini and a well-supported Celaenorrhinus clade, placing C. victor as sister to Celaenorrhinus consanguineus, while deeper nodes among major hesperiid lineages showed only moderate support in parts of the tree. Conclusions: This study provides a new mitogenomic resource for Celaenorrhinini and a comparative reference for codon usage and selective constraints within Celaenorrhinus, supporting the placement of C. victor within Hesperiidae while highlighting remaining uncertainty at deeper hesperiid divergences.