Comparative Mitogenomic Analyses of Psectrocladius (Diptera: Chironomidae)

<i>Psectrocladius</i>, a genus within the species-rich subfamily Orthocladiinae (Diptera: Chironomidae), remains poorly resolved in molecular phylogenetics due to limited available molecular data. Here, we sequenced and analyzed the complete mitogenomes of five <i>Psectrocladius</i> species, using two <i>Rheocricotopus</i> species as outgroups. Our results reveal that the mitogenomes of <i>Psectrocladius</i> are structurally conserved and retain a presumed ancestral gene order. The nucleotide composition of these newly generated mitogenomes exhibits a pronounced A + T bias, which is characteristic of typical insect mitogenomes. The substitution rates, estimated using Ka/Ks ratios, indicate that all protein-coding genes are under purifying selection. The strongest purifying selection pressure was observed in the <i>CO1</i> gene, while the weakest was in the <i>ND5</i> gene. Both the maximum likelihood and Bayesian inference trees consistently show the following topology: ((((<i>P. schlienzi</i> + <i>P. bisetus</i>) + <i>P. barbimanus</i>) + <i>P. oligosetus</i>) + <i>P. aquatronus</i>). This study provides key insights into chironomid mitogenomes and their gene properties, offering valuable reference data for future research.