The single mitochondrial chromosome typical of animals has evolved into 18 minichromosomes in the human body louse, Pediculus humanus

Evolution of minicircular mitochondrial (mt) chromosomes in the sucking lice of primates. The phylogeny of the sucking lice of primates and the estimate of the date of their most recent common ancestor (22.5 Mya) are after Barker et al. (2003) and Reed et al. (2004). The preferred habitats of lice on humans (i.e., body, head, and pubis) are in parentheses. The 18 minicircular mt chromosomes of the human body louse were sequenced entirely; the minicircular mt chromosomes of other lice were partially sequenced or identified by PCR tests (underlined). Hyphens link neighboring genes on the same minicircular chromosome.