Abstract:
In 1998-1999 The Nature Conservancy conducted a bioinventory of caves in Monroe and St. Clair counties in southwestern Illinois. This karst area comprises a small section of the Ozark Plateau isolated from the Missouri Ozarks by the Mississippi River. In the 71 sites that were sampled, 41 species thought to be globally rare were found and were assigned state (S) and global (G) ranks of rarity for conservation use. The list includes 10 species considered to be new to science and 12 species previously unreported from Illinois. Twenty four taxa were classified as obligate subterranean species, including four endemic species: the pseudoscorpion Mundochthonius cavernicolus, the amphipod Gammarus acherondytes, the milliped Chaetaspis sp. (undescribed), and the dipluran Eumesocampa sp. (undescribed). Gammarus acherondytes, recently listed as an endangered species, was found in six previously unsampled caves. All sites were rank-ordered according to the number of global and state rare species. The greatest single site diversity was found in Fogelpole Cave with 18 global and 20 state rare species. The highest subterranean drainage system diversity was found in the Danes/Pautler Cave System with 20 globally rare species. Fogelpole Cave also had the highest number of troglobites with 14 species. The Danes/Pautler Cave System again had the highest number of troglobites found in a groundwater system with 16 species.