The Highly Divergent Mitochondrial Genomes Indicate That the Booklouse, (Psocoptera: Liposcelididae) Is a Cryptic Species.

The booklouse, is an important storage pest worldwide. The mitochondrial (mt) genome of an asexual strain (Beibei, China) of the comprises two chromosomes; each chromosome contains approximate half of the 37 genes typically found in bilateral animals. The mt genomes of two sexual strains of , however, comprise five and seven chromosomes, respectively; each chromosome contains one to six genes. To understand mt genome evolution in , and whether is a cryptic species, we sequenced the mt genomes of six strains of asexual collected from different locations in China, Croatia, and the United States. The mt genomes of all six asexual strains of have two chromosomes. Phylogenetic analysis of mt genome sequences divided nine strains of into four groups. Each group has a distinct mt genome organization and substantial sequence divergence (48.7-87.4%) from other groups. Furthermore, the seven asexual strains of , including the published Beibei strain, are more closely related to two other species of booklice, and , than to the sexual strains of Our results revealed highly divergent mt genomes in the booklouse, , and indicate that is a cryptic species.