An electrophoretic analysis of the genetic relationship between Etheostoma nigrum and Etheostoma Olmstedi (percidae: etheostomatini) in the James River drainage of Virginia
Etheostoma nigrum Rafinesque 1820, the Johnny darter ranges from Alabama to the Hudson Bay and from Colorado east to the Atlantic slope in the James, Roanoke, Tar and Neuse Rivers. Etheostoma olmstedi Storer 1842, the tesselated darter, is restricted to the east coast in the Atlantic and Lake Ontario drainage. In the James and Roanoke River systems in Virginia E. nigrum occupies the piedmont and montane regions whereas E. olmstedi primarily inhabits the coastal plain. The relationship between the morphologically similar species of darters (subgenus Boleosoma) is controversial and has been investigated by several authors. Stone (1947), using multiple character analysis of the two forms in the zone of overlap in the Lake Ontario drainage, concluded that they were separate species. Hubbs and Lagler (1958) treated E. olmstedi as a subspecies of E. nigrum. Based on meristic data in a study of the two forms, Cole (1958, 1965 and 1967) supported Stone\u27s conclusions that separate species status is justified in drainages in New York, Virginia, and North Carolina. Scott and Crossman (1973) referred all Canadian Johnny darters to E. nigrum until it could be determined whether variation in the widespread form was somatic or genetic
