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Show Peter Hovingh Utah Museum of Natural History 721 Second Avenue, Salt Lake City, Utah 84103 PALEOZOOLOGICAL AND ZOOGEOGRAPHICAL STUDIES OF LEECHES ( HIRUDINEA) IN THE GREAT BASIN REGION OF WESTERN UNITED STATES Aquatic systems in the Great Basin and adjacent regions were surveyed for amphibians, mollusks, and leeches since 1985. The surveys consisted of visual encounters of lentic and lotic habitats and for the leeches and mollusks, sampling was performed with food strainer sifting sediment, and hand collecting from logs, rocks, plant roots, and debris. The leeches were relaxed with 1 to 10 dilution of 70% ethanol, fixed in 10% formalin overnight, and stored in 70% ethanol for identification. Both external characteristics and examination of internal organs, if necessary, were used in leech identification. The collection of USNM was examined for historic records and the specimens were verified or re- classified. Within the Great Basin, 19 species of were identified. This compares to some 34 leech species found in western North America, 66 species in North America, and some 500 leech species found worldwide. Generally, the leeches found in the Great Basin are found across northern United States and southern Canada. One endemic species was found in the Lahontan Basin ( Eagle Lake, Madeline Plains, Winnemucca Lake, and Granite Springs Valley). The species- rich basins include the Bonneville Basin ( 16 species), Lahontan Basin ( 12 species), and Franklin Basin ( 10 species). The passive movement of leeches by hosts could include the bird leeches ( Theromyzon rude, T. tessulatum, and T. trizonare) with 34 locations in the Great Basin, the mammal leech ( Placobdella ornata) with 29 locations in the Great Basin, and the amphibian leech { Desserobdella picta) with 4 locations in Utah. No fish leech was found in the Great Basin, although one record suggests that the fish leeches may be imported with exotic fish management. The mammal leech blood host is turtles ( mostly) and mammals in eastern North America whereas in the Great Basin where turtles are absent, mammals ( Pleistocene mammals, cattle, beaver) serve as the only blood host. The mammal and bird leeches were found with at least one other leech species at each location or in the same drainage or basin, suggesting that even these leech distributions need not be explained by host movement. The amphibian leech range was highly restricted considering the extensive range of its host, the tiger salamander in Utah. During pluvial- glacial periods of the Pleistocene, leeches occupied mid- elevational habitats from which they migrated both to lower and upper elevational habitats in post- pluvial times. Postglacial distribution of leeches in alpine lakes shows much variation with 9 species having occupied the glacial lakes in the last 10,000 years. Each mountain range has different leech components, largely based on the presence of leeches at mid- elevations, and secondary on geologic and geographic factors. The Colorado Rockies has the highest component ( based on Herrmann's work in Colorado) with 8 species; Medicine Bow Range, 6 species; Wasatch Range, 5 species; Southern Plateaus, 5 species; Uinta Range, 5 species; Sierra Nevada Range, 5 species; Steens Range, 3 species; Ruby Range, 2 species; Albion Range, 1 species; and Snake, Stansbury, and Jarbidge Ranges with no leeches. Helobdella stagnalis and Erpobdella punctata was found in |
