COSPECIATION OF POCKET GOPHERS (GEOMYS) AND THEIR CHEWING LICE (GEOMYDOECUS)

Comparison of independently derived phylogenies for pocket gophers (Ge omys) and their chewing lice (Geomydoecus) from Texas and Louisiana in dicates a history of widespread cospeciation in this host-parasite ass emblage. Inference of cospeciation is supported by statistical compari son of genetic-distance matrices for gophers and lice based on allozym e data. Although similar, host and parasite phylogenies are not identi cal; inconsistencies likely result from host-switching by the parasite s, retention of ancestral taxa of parasites on recently evolved hosts, or poorly delineated taxonomic boundaries. The current disjunct distr ibution of Geomydoecus ewingi suggests that this chewing louse once pa rasitized the common ancestor of Geomys breviceps and G. attwateri. Co mbined protein and morphologic evidence suggests that the population o f Geomydoecus ewingi hosted by G. breviceps breviceps in northeastern Louisiana ma be a cryptic species of louse.