Phylogenetic Relationships of Parasitic Psocodea and Taxonomic Position of the Anoplura1

Abstract

The phylogenetic relationships of five taxa of the Psocodea (Psocoptera, Amblycera, Ischnocera, Rhynchophthirina, and Anoplura) are analyzed cladistically. Fourteen character complexes including taxonomic characters used by previous workers were evaluated, and 21 characters were used for cladistic analysis. Theoretical aspects of phylogenetic inferences on the origin of higher taxa, monophyly and parallelism, and character polarity and weighting are discussed, and character selection and cladistic analysis are made on the basis of these theoretical premises. Extant higher taxa of the Psocodea are derived from a common ancestral stock. Similarities between Anoplura and other parasitic psocodean taxa are primarily the result of parallel evolution due to similar habitats and adaptive roles. Primitive psocodean ancestors invaded new habitats (skin surface and dermal derivatives of birds and mammals) and niches, perhaps during the late Triassic and Jurassic Periods. The Anoplura must have been separated from the main psocodean line quite early in evolutionary time. It is quite probable that the Protanoplura made two major evolutionary shifts: (1) the invasion of a new habitat, perhaps between the Jurassic and Cretaceous Periods; and (2) the development of a new food source (the blood) after the Cretaceous period. Once established on the mammalian hosts, the Protanoplura evolved rapidly and acquired key characters. We conclude that the sucking lice (Anoplura) are distinct from the chewing lice and should retain the rank of order. Likewise, the order Mallophaga (including three suborders, Amblycera, Ischnocera, and Rhynchophthirina) must be retained. A key to the orders and suborders of the Psocodea is presented.