Great Basin Naturalist


Some biogeographical and paleobiological aspects of leeches, mollusks, and amphibians in the Intermountain Region are reviewed. Areas of eastern Nevada and western Bonneville Basin as well as the tristate region of Nevada, Utah, and Idaho are poorly inventoried with respect to many aquatic-dependent animals. Observations of Batracobdella picta in the Wasatch Mountains and Erpobdella punctata in Tule Valley in the Bonneville Basin extends the western ranges of these leeches in the Great Basin. Life history and size of leeches varies among the study sites in the northern hemisphere. Aquatic mollusk species have diminished greatly in both prehistoric and historic times, as demonstrated by Utah Lake where some 30 species once lived. Eight genera survived into historic times, and perhaps only one species presently lives there. Extinction of numerous mollusks in the Bonneville Basin is still unknown with respect to cause and time. The finding of the Western Spotted Frog (Rana pretiosa) in Tule Valley reveals both a different habitat for this species when compared to other study sites and that this species must have occupied the region during Lake Bonneville times. With the exception of the Leopard Frog (Rana pipiens), most other amphibians probably migrated into the Bonneville Basin after the desiccation of Lake Bonneville.