Distributional Associations Among Geomydoecus and Thomomydoecus Lice (Mallophaga: Trichodectidae) and Pocket Gopher Hosts of the Thomomys Bottae Group (Rodentia: Geomyidae)1

A computerized taxonomic and geographic storage, retrieval, analysis, and distribution mapping system was used to evaluate 51,670 specimens of Geomydoecus and Thomomydoecus chewing lice collected from 226 species and subspecies of the pocket gophers Thomomys bottae, T. umbrinus, T. townsendii, and T. bulbivorus. These lice consisted of 52 species and subspecies in 8 complexes. Comparison of the geographic ranges of louse complexes with those of associated host taxa showed that, while most host taxa had a fairly uniform louse fauna, 70 subspecies possessed geographically separated localities with 2 or more louse taxa from the same genus. The distribution of louse complexes corresponded reasonably well to pocket gopher species but showed a somewhat different separation between T. bottae and T. umbrinus than that presently defined by gopher taxonomists. Comparison of geographically isolated host populations based on louse associations showed both similarities to and differences from that based on allozymal similarity among the hosts, with the louse-based groups geographically well defined. Individual hosts rarely harbored more than 1 louse species per genus, and in 1 case where this occurred the host was found to be an F1 hybrid of parental taxa that were each associated with 1 of the louse species.