Presumably, the pocket gopher hosts and their lice parasites would speciate in response to the same vicarriant barriers or dispersal events. However, 3 closely related lice (Geomydoceus thomomyus, actuosi, and ewingi) infest two distantly related pocket gophers (Thomomys and Geomys) Hafner, M.S. and Nadler, S.A. 1991. Cospeciation in host-parasite assemblages: Analysis of rates of evolution and timing of speciations events. Systematic Zoology 39: 192-204.