Many taxonomic groups successfully exploit groundwater environments and have adapted to a subterranean (stygobiotic) existence. Among these groups are freshwater gastropods (stygosnails), which represent a widespread and taxonomically diverse component of groundwater ecosystems in North America. However, owing to sampling difficulty and lack of targeted study, stygosnails remain among the most understudied of all subterranean groups. We conducted a literature review to assess the biodiversity and geographic associations of stygosnails, along with the threats, management activities, and policy considerations related to the groundwater systems they inhabit. We identified 39 stygosnail species known to occur in a range of groundwater habitats from karst regions in the United States and Mexico. Most stygosnails exhibit extreme narrow-range endemism, resulting in a high risk of extinction from a single catastrophic event. We found that anthropogenically driven changes to surface environments have led to changes in local hydrology and degradation of groundwater systems inhabited by stygosnails such as increased sedimentation, introduction of invasive species, groundwater extraction, or physical collapse of water-bearing passages. Consequently, 32 of the 39 described stygosnail species in the United States and Mexico have been assessed as imperiled under NatureServe criteria, and 10 species have been assessed as threatened under International Union for Conservation of Nature criteria. Compared with surface species of freshwater snails, stygosnail conservation is uniquely hindered by difficulties associated with accessing subterranean habitats for monitoring and management. Furthermore, only three species were found to have federal protection in either the United States or Mexico, and current laws regulating wildlife and water pollution at the state and federal level may be inadequate for protecting stygosnail habitats. As groundwater systems continue to be manipulated and relied on by humans, groundwater-restricted fauna such as stygosnails should be studied so unique biodiversity can be protected.
Abstract:The genus Speleonycta is erected, and S. ozarkensis, n. sp., is described and separated from other species of the subfamily Cubacubaninae. The type species was collected from several caves in the Ozark Plateau, while two more species, collected from a cave in Arizona and from a cave in California, remain under study. Morphology and preliminary analyses using histone DNA indicate that the new genus may be related to Texoreddellia, another nicoletiid from caves of Texas and northern Mexico.
Six new species of Collembola of the family Arrhopalitidae are described from the United States (Pygmarrhopalites leonardwoodensis sp. nov., P. plethorasari sp. nov., P. youngsteadtii sp. nov., P. buffaloensis sp. nov., P. shoshoneiensis sp. nov., and P. ashcraftensis sp. nov.) from caves in Missouri (2 spp.), Arkansas (2 spp.), Nevada, and Indiana, respectively. These new taxa, which display varying degrees of troglomorphy, are compared with previously known species and bring the total described species in North America to 41.
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