Discovery of a new population of the federally endangered Alabama Cave Shrimp, Palaemonias alabamae Smalley, 1961, in northern Alabama

The Alabama Cave Shrimp Palaemonias alabamae Smalley, 1961 is a federally endangered cave shrimp endemic to just four cave systems within and near the greater Huntsville metropolitan area in Madison County, Alabama USA. It is one of two described atyid cave shrimp in the Interior Low Plateau karst region. Here we report the discovery of a new population of P. alabamae from the Fern Cave system in western Jackson County, Alabama. We observed four cave shrimp in August 2018 in an isolated pool in the base-level stream passage of the longest cave system in Alabama. Two cave shrimp were observed during a subsequent survey in July 2019: one in the same isolated pool and a second shrimp in a pool in the main stream passage. Morphological and genetic analyses confirm that this population is closely allied with other populations in Madison County. This new population expands the known distribution of the species into a new county and watershed (Lower Paint Rock River). The potential exists to discover additional populations in Paint Rock River valley and other nearby regions.