Historically, the southern acornshell occurred in the upper Coosa River system and upstream of the fall line on the Cahaba River in Alabama, Georgia, and Tennessee. The southern acornshell was last collected in 1973 from the Conasauga River in Georgia and from Little Canoe Creek, near the Etowah and St. Clair county line, Alabama (Williams et al. 2008, Shelton-Nix 2017); and has not been collected from the Cahaba River since the 1930s (58 FR 14330). It was the Service’s determination at the time of listing, with consensus of the malacological community that this species was likely to persist in low numbers in the upper Coosa River drainage, and possibly in the Cahaba River. Since that time, multiple surveys in the Coosa River tributaries have been conducted by Service biologists, as well as Bogan and Pierson (1993a), Dinkins (2008), Dinkins and Hughes (2011), Fobian et al. 2017, Gangloff (2003, 2005), Golder Associates 2008, Johnson (2006), Johnson and Evans (2000), Johnson et al. 2005, Johnson et al. (2006), Pierson (1993), McGregor and Garner (2004), Williams and Hughes (1998), Krause et al. (2012), and all have failed to report the southern combshell. Surveys of the Cahaba River have been conducted by Service biologists, Bogan and Pierson (l993b), Freeman 2011, McGregor et al. (2000), McGregor and Garner (2004), Shepard et al. (1994, 1998), Gangloff (2006), and others. Despite these repeated surveys of historical habitat in the Coosa and Cahaba River drainages, no living animals or fresh or weathered shells of this species have been located. Recent authors have presumed the species to be extinct (Evans 2001, Gangloff 2003, Gangloff and Feminella (2007), Williams et al (2008), and Shelton-Nix (2017). Considered extinct by many experts