New mitogenomic evidence for the phylogeny of Siphonaptera: insights from Callopsylla dolabris and Oropsylla silantiewi
As important vectors of infectious diseases such as plague, fleas require accurate classification and phylogenetic analysis, which are essential for public health prevention and control. However, complete mitochondrial genome resources for Siphonaptera in public databases are still extremely scarce. In this study, the complete mitochondrial genomes of C. dolabris and O. silantiewi, collected from the high-altitude region in Qinghai Province, were sequenced and characterized for the first time using next-generation sequencing technology. The results showed the two mitogenomes were 17,104 bp and 15,914 bp in length, respectively. Both mitogenomes exhibited significant A+T bias and a strong preference for A/U-ending codons. Selective pressure analysis (Ka/Ks) indicated that mitochondrial protein-coding genes (PCGs) of fleas are predominantly under purifying selection. Phylogenetic reconstructions based on 39 mitogenomic sequences from 36 flea species revealed that Ceratophylloidea was robustly supported as monophyletic. At the family level, neither Ceratophyllidae nor Leptopsyllidae formed a strictly monophyletic group in the present dataset. Pulicidae was recovered as a well-supported monophyletic clade. Both newly sequenced species were placed within Ceratophyllidae. This study not only expands the available mitogenomic resources for Siphonaptera, but also provides new insights into nucleotide composition patterns and phylogenetic relationships within the order.