TAXONOMY OF SUBFOSSIL MICROGASTROPODS FROM BEAR LAKE, UTAH-IDAHO BORDER

Bear Lake is a fault-bounded lake spanning the Utah-Idaho border. Presently, the invertebrate population of the lake is limited to insect nymphs. In the recent past, however, Bear Lake was home to a diverse assemblage of mollusks that now exist as subfossils in the sediment surrounding the lake. All of these species are now locally, and in some cases regionally, extinct. Previous taxonomic studies of this fauna have concentrated exclusively on the larger genera of mollusks. However, the shoreline of Bear Lake also has a rich fauna of smaller microgastropods, primarily of the family Hydrobiidae. In this study, we combined scanning electron microscopy with systematic descriptions of extant hydrobiid gastropods in the region, to identify the species comprising this surprisingly rich fauna.