Cumberland Elktoe

The Cumberland elktoe has a thin, but not fragile, shell. The outside surface of the shell (periostracum) is smooth, somewhat shiny, and covered with greenish rays. Young specimens have a yellowish brown periostracum, while specimens of adults are generally much darker. The inside surface of the shell (nacre) is shiny, with the color being white, bluish white, or sometimes peach or salmon.

The Cumberland elktoe is endemic to the upper Cumberland River system, and it still exists in 12 mostly small tributaries in southeast Kentucky and north-central Tennessee. The Cumberland elktoe is limited in distribution to the upper Cumberland River system in southeast Kentucky and north-central Tennessee, occupying streams both above and below Cumberland Falls. This species appears to have occurred only in the main stem of the Cumberland River and primarily its southern tributaries upstream from the hypothesized original location of Cumberland Falls near Burnside, Pulaski County, Kentucky. The original type locality was simply "river Cumberland," according to Clarke, who, upon ascertaining that the type specimen was lost, designated a neotype from the Clear Fork, a tributary to the Big South Fork, in Fentress County, Tennessee. All verified sites of occurrence are in the Cumberland Plateau Physiographic Province, giving it one of the most restricted ranges of any Cumberlandian species. There has been confusion about the historical distribution of this species because of its similarity to a congener – the elktoe (Alasmidonta marginata). Museum and literature records of Alasmidonta marginata from the Cumberland River drainage on the Cumberland Plateau should be verified because they may actually represent the Cumberland elktoe. …