Co-evolution of trichodectid lice (Insecta: Phthiraptera) and their mammalian hosts

The cladogram of Trichodectidae produced by Lyal (1985) is interpreted, with reservations, as a phylogeny is compared to such host phylogenies as are available. While the predominant pattern of louse associations is broadly congruent with host relationships, indicatiing phyletic tracking or a mixture of phyletic tracking and and host-group-limited resource tracking by the lice, a substancial proportion (20.7%) of speciation events of the lice could only be explained by involking secondary infestation of distantly related hosts by the lice. The ancestor of the Trichodectidae almost certainly parasitised a eutherian, but the identity of the eutherian group is unclear. The primary host association for the neotrichodectinae was with an American rodent from which resource tracking on to Mephitinae and then Mustelinae, Procyonidae, Braypodidae and Melinae took place. The Trichodectinae had an ancestral association with the ancestor of the Feloidea, with subsequent secondary infestation of Mustelidae, Canidae, Ursidae, Procyonidae. The parasitism of the feloid ancestor was probably derived by secondary infestation from a rodent of hyracoid. The ancestral host of the Dasyonyginae may of been a hyracoid. The ancestral host of the Dasyonyginae may of been a hyracoid, and two secondary infestations of primates are recorded in the subfamily. The erethizontid hosts of the Eutrichophilinae gained their lice from an unknown host. The ancestral host of the Bovicolinae is not known. Future work to resolve these problems must involve:(1) Further collection of lice, with particular emphasis on Artiodactyla, Perissodactyla and Carnivora. (2) Further investigation of the cladistic relationships of the Trichodectidae, particularly the primary furcations of the cladogram proposed by Lyal (1985), where apomorphies have been very difficult to discern, and in the Bovicolinae. (3) Production of a more fullly resolved cladogram of the Eutheria, and the identification of holophyletic mammalian groups at all levels.