ABSTRACT
Contents Introduction........................................................................................................................205 Mycetomes in Psocoptera .................................................................................................206 Wolbachia in Psocoptera .................................................................................................... 209 Mycetomes and endosymbionts in Phthiraptera .......................................................... 210
Amblycera ...................................................................................................................... 210 Ischnocera ...................................................................................................................... 211 Rhyncophthirina ........................................................................................................... 212 Anoplura ........................................................................................................................ 212
Nutritional provisions of Riesia pediculicola ................................................................... 213 Medical implications of endosymbionts of human lice ............................................... 214 References ........................................................................................................................... 216
Introduction Lice belong to the larger, monophyletic assemblage or proposed superorder of the Paraneoptera encompassing the Psocoptera (psocids or booklice, barklice and barkies, and formerly Corrodentia), Phthiraptera (true lice), Thysanoptera (thrips), and the Hemiptera (true bugs including, among others, leafhoppers, treehoppers, cicadas, aphids, scale insects, whiteies, psyllids, spittlebugs, and ground pearls). Increasingly, the psocids and true lice are grouped together as Psocodea opposite the Condylognatha, which comprise the thrips and true bugs. Psocoptera and Thysanoptera are considered the more basal orders of the two groupings. Psocodea encompass more than 10,000 species almost equally divided between booklice and barklice, and true lice. The psocodeans are the only insects that can absorb water vapor in the adult stage, which may have preadapted them to invading habitats where access to water is a scarcity (Grimaldi and Engel, 2005). The number of psocopteran species might be underestimated because of their limited economical importance compared to true lice. On the other hand, all lice species are parasitic and as the only insect taxon, parasitic at all life stages. In 1945, already 54% of the families and 67% of the genera of all mammals had been reported extinct (Simpson, 1945; Grimaldi and Engel, 2005). Since then, many more new species of mammals have been described from fossils than from living specimens (McKenna and Bell, 1997). Considering the host specicity of lice, the majority of lice species and genera may have been lost as well. An understanding of the host phylogenesis is important for unraveling the evolution of parasitism and endosymbiosis in lice.
