BIOGEOGRAPHIC ASPECTS OF LEECHES, MOLLUSKS, AND AMPHIBIANS IN THE INTERMOUNTAIN REGION Peter Hovingh' Abstract. — Some biogeographical and paleobiological aspects of leeches, mollusks, and amphibians in the Inter-mountain 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 Erpohdella 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 {Rami prctiosa ) 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. For eight years I have examined many ponds and springs to determine the distribu-tion of amphibians and their breeding habitat requirements in such rather diverse arid re-gions as the Bonneville Basin and the Colo-rado Plateau as well as the regions of high precipitation, such as the Wasatch and Uinta mountains. It soon became apparent that, with the exception of the threatened and en-dangered species, very httle systematic work had been done on the distribution of native aquatic species in the Intermountain Region. Most of the work was done before 1940. To-day, with more and better roads and a very extensive inventory of the water resources, it seemed that new attempts should be made, especially in view of the recent efforts in un-derstanding the hydrological basins and their paleo-history. This paper reviews certain aspects of leeches, mollusks, and amphibians with the idea that with more information one might better understand their present distribution as well as their past distribution during the era of glaciers and the pluvial lakes. This paper is divided into three separate sections: (1) bio-geographical distribution and life history vari-ations of leeches, (2) review of mollusks in the Bonneville Basin, and (3) notes on the distri-bution of amphibians in Utah and Nevada. Leeches With the exception of Herrmann's work (1970) in Colorado, neither Nevada nor Utah have been methodically investigated for leeches. Twenty-one species were identified from Colorado (Klemm 1982, Herrmann 1970). Ten of these occur in western Colorado in the Middle Rocky Mountain Province and the Colorado Plateau Province (Herrmann 1970). Eight of these western Colorado spe-cies were found in Utah (Beck 1954, Barnes and Toole 1981) and four of them were found in Nevada (Klemm 1982). Table 1 lists the distribution. Note the lack of Erpobdellidae in Nevada. Observations oi Placobdella ornata (Verrill 1872) in western Colorado, P. multilineata (Moore 1953) in the Uinta Basin of Utah, and P. parasitica (Say 1824) in Nevada need fur-ther clarification. Only in Nevada (Truckee River drainage) does the turtle host exist within this region. Theromijzon rude (Baird 1869) was found in both Nevada and Colorado and should be found in Utah. The above leeches will not be discussed further. Batracobdella picta (Verrill 1872) was re-ported from Current Creek, Wasatch County, Utah at 1,980 m elevation in a bog (Beck 1954). 1 found this leech very numerous on larval salamanders of Ambystoma tig,rininn in Department of Biocht-mistrv-. Ur ityoi Utah, Salt Lake City. Utah. Correspoiulf L'lit to 721 Second .Avcmie, Salt Lake City. Utah 84103. 736
BioStor
