Kidneyshell Ptychobranchus fasciolaris. Rare. Restricted to Tennessee River system. Extant in tailwaters of Wilson and Guntersville dams, Paint Rock River system, and a short reach of Bear Creek in Colbert County. Always found in flowing water. HIGHEST CONSERVATION CONCERN.
Triangular Kidneyshell Ptychobranchus greenii. Rare. Endemic to Mobile Basin upstream of the Fall Line. Extant in a few tributaries of most major rivers in that system. Possible species complex. Occurs in shoal habitats. Listed as endangered by the U.S. Fish and Wildlife Service. HIGHEST CONSERVATION CONCERN.
Southern Kidneyshell Ptychobranchus jonesi. Rare. Endemic to Gulf Coast drainages. Historically found in Choctawhatchee, Escambia, and Yellow river systems. Only known extant population is in West Fork Choctawhatchee River. Usually found in areas with at least some current. Listed as endangered by the U.S. Fish and Wildlife Service on October 12, 2012. HIGHEST CONSERVATION CONCERN.
Fluted Kidneyshell Ptychobranchus subtentum. Extirpated. Endemic to Cumberlandian Region. Historically occurred downstream to Muscle Shoals. Has not been reported from Alabama since river was impounded. Restricted to shoal habitats. Recent candidate for federal protection.