Comparative analyses of the fragmented mitochondrial genomes of wild pig louse Haematopinus apri from China and Japan

The wild pig louse Haematopinus apri is one of the commonest ectoparasites of wild pigs. In the present study, the entire mitochondrial (mt) genome of wild pig louse H. apri from China was sequenced and compared with previously characterized wild pig louse H. apri from Japan. We identified all of the 37 mt genes in the wild pig louse H. apri from China which are on nine circular minichromosomes. Each mt minichromosome is 2.9 kb–4.2 kb size and contains 2–8 genes and one non-coding region (1543 bp-2534 bp). The number of minichromosomes, gene content and gene order in the both mt genomes of wild pig louse H. apri from China and Japan is the same. The identity of the both mt genomes (except for non-coding regions) was 98.3% between wild pig louse H. apri from China and Japan. The entire mt genome sequence (except for non-coding regions) of wild pig louse H. apri from China is longer (3 bp) than that from Japan. For the 13 protein-coding genes, this comparison showed sequence differences in each gene at both the nucleotide (0.8%–2.4%) and amino acid (0.4%–3.5%) levels. The most conserved of these genes was the nad6, whereas the nad2 was least conserved at the nucleotide levels. This is the first comprehensive comparison of the mt genomes of a louse species from different geographic locations. This useful data provides additional genetic markers to study the phylogeny, systematics and population genetics of wild pig louse H. apri.