Open Access

Robert Hershler

• A recently completed field survey of springs throughout the Great Basin yielded collections of hydrobiid snails from more than 500 sites, and revealed a wealth of undescribed diversity of these small gastropods. In this, the first or a two-part taxonomic series treating this material, 58 new species of Pyrgulopsis Call & Pilsbry, 1886, are described; and new records are provided for 10 previously described members of this genus. Assignment of these novelties to Pyrgulopsis is done with the acknowledgement that this large genus, as currently constituted, is probably not monophyletic, but a more refined classiffcation of these snails reflecting evolutionary relationships must await preparation of a phylogenetic analysis, which is beyond the scope of this work. Pyrgulopsis occur in a variety of spring-fed water bodies in the Great Basin, including brackish and/or thermal habitats. Although a few species are widespread in the region, local endemism is prevalent lind 22 of the new species are known only from single localities. Several areas contain concentrations of locally endemic snails which may represent species flocks, notably Duckwater Valley (seven species) and southern Steptoe Valley (five species). This fauna is hugely distributed in an allopatric fashion, although a few springs harbor two or three species. Most of the springs inhabited by hydlrobiids in the region are small, fishless, and have been ignored by state and federal land management agencies. However, many of these sites are degraded by livestock grazing, water withdrawal, anti other activities and will require protection in order to conserve snails and other native aquatic biota. Two of the novellies described herein have become extinct during the past two decades.