Range Description

This species is native to the middle and south Caspian Sea where it is found at depths of 20-80 m (Therriault et al. 2004). While it has never been reported outside this historical distribution, a freshwater 'race' (the Quagga Mussel, D. r. bugensis Andrusov, 1897) has spread from the Black Sea basin northeast along the Volga River into Russia, north along the Dnieper River into Ukraine, and west along the Danube canal and Rhine as far as the Netherlands (van der Velde and Platvoet 2007). The Quagga 'race' has also spread to North America, where it was first reported (from Lake Ontario) in 1991 (Therriault et al. 2004), and has since spread throughout the Great Lakes region and southwest to the Mississippi River, Nevada, Colorado, Arizona and California (Benson et al. 2011).

Kantor et al. (2009) list several other subspecies, separated from one another by habitat zonation. D. r. compressa (Logvinenko & Starobogatov, 1966) is restricted to the Caspian Sea at depths of 70-300 m. D. r. grimmi (Andrusov, 1890) occurs in the Middle Caspian Sea from 45-80 m depth. Lastly, D. r. pontocaspica (Andrusov, 1897) is known from the southwestern and southeastern Caspian, at 20-80 m in depth.