Elucidating ectoparasitic earwig evolution

Dermaptera is a comparatively small order of insects with approximately 1800 species placed in three subfamilies. While the majority of earwig species are placed within the suborder Forficulina and are free-living with forceps-like appendages, two dermapteran lineages have a very unusual morphologies and life histories. The viviparous Hemimerina live epizoically on giant rats in tropical Africa where they feed on fungi growing on the rats’ skin. Hemimerina lack eyes and wings and the cerci are filiform. The viviparous Arixenina are associated with bats in Malaysia and the Phillipines, and they feed on bat skin gland secretions. They have reduced eyes, are wingless, and possess straight cerci. The phylogenetic position of Arixenina and Hemimerina relative to Forficulina is unclear, and thus it is uncertain how many times ectoparasitism has evolved in Dermaptera. We generated DNA sequence data from three nuclear (18S, 28S and H3) and one mitochondrial (COI) gene for representatives of all three suborders and outgroups. A phylogeny was reconstructed to address the following questions: (1) Does Hemimerina + Arixenina form a monophyletic group and support a single origin of parasitism or are there multiple origins of parasitism? (2) Is Forficulina monophyletic with respect to these parasitic lineages? (3) Are morphological similarities shared by the ectoparasitic forms synapomorphic or homoplasious characters?