Abstract:  【Aim】 The typical single-chromosome mitochondrial (mt) genome of animals has fragmented into multiple mt minichromosomes in Hoplopleura genus. To infer the ancestral mt karyotype for Hoplopleura genus, we sequenced the mt genome of Hoplopleura pacifica. 【Methods】 We sequenced the fragmented mt genome of H. pacifica by Illumina HiSeq X Ten platform, and analyzed the structure and variation. We constructed phylogenetic trees of 15 species of sucking lice in 7 genera and 7 families by using maximum likelihood method and neighbor-joining method, and inferred the ancestral mt karyotype of Hoplopleura by parsimony method. 【Results】 We identified 29 mt genes (11 protein-coding genes, 16 tRNA genes and 2 rRNA genes) from mt genome of H. pacifica, which are unevenly distributed on 10 mt minichromosomes. The coding region of each mt minichromosome contains 1-5 genes with the length of 690-1 773 bp. Species of Hoplopleura have a little difference in structure of mt minichromosomes. Compared with other genera in Anoplura, Hoplopleura have variation in the gene composition and gene arrangement of mt minichromosome, which, however are only limited to tRNA genes. The phylogenetic tree showed that Anoplura was divided into two major clades with strong supports, one major clade included the lice of Hoplopleuridae, Polyplacidae, Haematopinidae and Microthoraciidae, and the other major clade included the lice of Pediculidae, Pthiridae, and Pedicinidae. The ancestral mt karyotype of Hoplopleura comprises 12 mt minichromosomes, each having a single coding region with 1-6 genes and a single non-coding region. 【Conclusion】 We successfully sequenced and analyzed the fragmented mt genome of H. pacifica for the first time, compared it with the mt genome of the other two Hoplopleura species sequenced to date, and inferred the ancestral mt karyotype of Hoplopleura.

Key words: Hoplopleura, Hoplopleura pacifica, mitochondrial genome, mitochondrial minichromosome, mitochondrial karyotype, genome fragmentation