A penguin-chewing louse (Insecta : Phthiraptera) phylogeny derived from morphology

Penguins are parasitised by 15 species of lice in the genera Austrogoniodes and Nesiotinus and present an opportunity to analyse phylogenetic relationships of two complete genera of chewing lice parasitising a monophyletic group of hosts. Taxonomy of penguin lice has been revised several times, including the erection of the genus Cesareus to contain some of the penguin-chewing louse species. Additionally, other groups of species within Austrogoniodes have been proposed. We constructed a phylogeny for all the chewing lice parasitising penguins from 46 parsimony-informative morphological characters and found support for two groups within Austrogoniodes, but little support for the Cesareus genus. Austrogoniodes metoecus, the only Austrogoniodes species parasitising a bird other than a penguin, was basal in the phylogeny, which suggests that if A. metoecus did originate from a louse species parasitising penguins, the host-switching event was unlikely to have been recent. A superficial comparison of louse and penguin phylogenies identified some potential instances of co-speciation. However, a full analysis of co-phylogenetic relationships between penguins and their lice awaits the publication of a better-resolved penguin phylogeny.