A new Somatogyrus from the southwestern Ozarks with a brief review of the Hydrobiidae from the Interior Highlands (Gastropoda: Prosobranchia)

A previously unknown Somatogyrus is described from the Elk River, McDoridld County, Missouri. With this description, the number of Hydrobiidae presently recorded from the Interior Highlands increases to 15, including 11 regional endemics. Nine species are endemic to the Ozark Plateaus, while two Somatogyrus are restricted to the Ouachita Mountains. Fire of the Ozark endemics are obligate troglohites. Troglobitic Amnicola antroecetes (Hubrichf) is considered distinct from epigean A. aldrichi (Call and Beecher).