Host associations, host switching, geographic location, and potential reticulate evolution shape the systematics of sucking lice (Psocodea: Anoplura) belonging to the genera Hoplopleura and Polyplax

Sucking lice (Psocodea: Anoplura) represent a species-rich parasite group that shares an intimate evolutionary relationship with their mammalian hosts. Two anopluran genera, Polyplax and Hoplopleura, primarily parasitize rodents and the taxonomy of these lice is mainly based on morphological characters with some inferences derived from host associations. To shed more light on the systematics and the evolutionary mechanisms that gave rise to Polyplax and Hoplopleura species diversity, data derived from the 16S rRNA, COI, 18S rRNA, and EF-1α genes were used to generate a phylogeny for 105 individuals representing ∼56 morphologically identified species. Concatenated data analyses found significant nodal support for five higher level monophyletic Clades among Hoplopleura and four higher level Clades and 15 subclades among Polyplax species. The monophyly of neither Polyplax nor Hoplopleura was supported and topological conflict among individual gene trees resulted in a non-tested hypothesis that ancestral hybridization and/or independent lineage sorting may have shaped the evolution of some Polyplax species. Several species complexes or cryptic divergences were detected specifically within the hoplopleurid species Hoplopleura acanthopus, Hoplopleura arizonensis, Hoplopleura hesperomydis, Hoplopleura oryzomydis, Hoplopleura pacifica, and Hoplopleura sciuricola, and the polyplacid species Polyplax arvicanthis, Polyplax auricularis, Polyplax biseriata, Polyplax myotomydis, Polyplax otomydis, Polyplax reclinata, and Polyplax spinulosa. Four morphological and genetically distinct taxa were sampled from Gerbillinae or Deomyinae and these probably represent new species. The taxonomy of Polyplax and Hoplopleura needs a thorough revision, and the species diversity of these lice can be attributed to an interplay between host associations, host switching and geographic locations of host species.