Distribution and Conservation Status of the freshwater gastropods of Nebraska

This survey of freshwater gastropods within Nebraska includes 159 sample sites and encompasses the four primary level III ecoregions of the State. I identified sixteen species in five families. Six of the seven species with the highest incidence, Physa gyrina, Planorbella trivolvis, Stagnicola elodes, Gyraulus parvus, Stagnicola caperata, and Galba humilis were collected in each of Nebraska’s four major level III ecoregions. The exception, Physa acuta, was not collected in the Western High Plains ecoregion. Seven indigenous species, Valvata tricarinata, Helisoma anceps, Campeloma decisum, Galba bulimoides, Physa jennessi, Ferrissia rivularis, and Planorbula armigera, display incidence rarity, being collected at five or fewer samples sites. The non-indigenous Chinese mystery snail, Bellamya chinensis, was collected at five sites all within southeastern Nebraska. The Nebraska Sand Hills had the highest species richness, with 12 species. The wetland complex with the highest species richness of 8 was the lakes region of the Nebraska Sand Hills. Reservoirs and permanent/semi-permanent water bodies were the most species rich among water body types and hydrologic conditions with 13 and 14 species respectively. I assign a tentative conservation status to each species of indigenous freshwater snail observed following a modified quartile analysis.