Rediscovery and phylogenetic analysis of the Shelta Cave Crayfish (Orconectes sheltae Cooper & Cooper, 1997), a decapod (Decapoda, Cambaridae) endemic to Shelta Cave in northern Alabama, USA

The Shelta Cave Crayfish (Orconectes sheltae) is a small, cave-obligate member of the genus Orconectes (family Cambaridae) endemic to a single cave system—Shelta Cave—in northwest Huntsville, Madison Co., Alabama, USA. Although never abundant, this stygobiont was regularly observed in the 1960s and early 1970s before the population and aquatic community in general at Shelta Cave collapsed likely in response to groundwater contamination and the loss of energetic inputs from a Grey Bat (Myotis grisescens) maternity colony that abandoned the cave after installation of a poorly designed cave gate. We conducted 20 visual surveys of aquatic habitats at Shelta Cave between October 2018 and July 2021. Although the aquatic community has not recovered, we did confirm the continued existence of O. sheltae, which had not been observed in 31 years, with observations of an adult female on 31 May 2019 and an adult male on 28 August 2020. We conducted the first phylogenetic analyses of O. sheltae and discovered that the species is most closely related to other geographically proximate stygobiotic crayfishes in the genus Cambarus in northern Alabama than members of the genus Orconectes. We advocate for recognition of this species as Cambarus sheltae to more accurately reflect evolutionary relationships of this single-cave endemic and offer recommendations for its management, conservation, and future research, as this species remains at high risk of extinction.