Intra-genus variation in mitochondrial minichromosome composition among Haematopinus sucking lice

There are 21 species of blood-sucking lice in the genus Haematopinus; these lice parasitize pigs, hogs, cattle, buffaloes, antelopes, horses, donkeys, zebras and deer. The mitochondrial genomes of the domestic pig louse Haematopinus suis and the wild pig louse Haematopinus apri have been sequenced recently; both species have fragmented mitochondrial genomes with 37 genes on nine minichromosomes. To understand whether the composition of mitochondrial minichromosomes is stable at low taxonomic levels, we sequenced the mt genome of the horse louse Haematopinus asini. We identifi ed all of the 37 mitochondrial genes typical of animals except nad6 gene in the horse louse; these genes are on nine minichromosomes. Seven of the nine minichromosomes of the horse louse have their counterparts in the pig lice with identical gene content and gene arrangement. The other two minichromosomes of the horse louse, however, are not seen in the pig lice. Our results revealed variation in the composition of mitochondrial minichromosomes among closely related species of sucking lice in the same genus. We propose that the variation is likely caused by gene deletions and recombination between minichromosomes