As a continuation of the work on Canthon humectus (Say) (see Introduction), in this article we carry out a taxonomic and biogeographic study of the taxa of the humectus group of western Mexico, specifically, the mountain ranges of the state of Jalisco. In this region of rugged terrain, the Western Sierra Madre Occidental Mountain Range, the Trans-Mexican Volcanic Belt, and the Southern Sierra Madre Mountain Range converge, and there are four taxa belonging to what we here consider the humectus group. As the basis for this new taxonomic situation and the taxa that comprise it, we present a description of the humectus group and a key for all of the species and subspecies in it. Also included is the description or diagnostics of the taxa found in the mountains and on the coast of Jalisco: Canthon humectus humectus (Say), C.h. assimilis Robinson, C. riverai Halffter and Halffter st. nov. y C. occidentalis Halffter and Rivera sp. nov. The coexistence of pairs of these taxa in several localities, with no transition specimens, highlights the need to treat some of them as species separate from C. humectus, but still within the humectus group. The comparison of the degree of hybridization among taxa that occurs in the mountains of Jalisco with that which has already been studied in eastern Mexico, is thought to be the result of two historical periods of dispersal-speciation in the humectus group. This is a hypothesis, the acceptance or rejection of which will depend on comparative molecular DNA studies of the Jalisco taxa with that of eastern Mexico.
