Abstract: To understand the complete sequence information of mitochondrial 16S rRNA gene and the phylogenetic relationships of Mesostigmata species, the mitochondrial genome of Parasitus fimetorum was sequenced by PCR and combined with the sequence information of most taxa of Mesostigmata in the NCBI database. A comparative analysis of mitochondrial 16S rRNA genes of Mesostigmata species was performed using bioinformatics software to further explore the phylogeny and relation among Mesostigmata species. The results showed that the AT content of the mitochondrial 16S rRNA genes of Mesostigmata species was much higher than the GC content; the genetic distance ranged from 0.111 to 0.359, with an average genetic distance of 0.291. The base conversion to inversion ratio and sequence saturation analysis showed that the mitochondrial 16S rRNA genes of Mesostigmata species had a high evolutionary potential suitable for phylogenetic analysis. The phylogenetic trees constructed using ML and BI methods showed that Parasitidae formed sister branches with the Ologamasidae, which differed from the traditional taxonomic results. Most species of the same family always preferentially clustered together, indicating that the mitochondrial 16S rRNA gene was used to construct phylogenetic relationships of Mesostigmata with stable and reliable characteristics. The above results provided a foundation for the subsequent study of the phylogenetic relationships of Mesostigmata species.

Key words: Mesostigmata, DNA barcoding, mitochondrial genome, 16S rRNA, phylogeny