88 Paul W. Parmalee, Walter E. Klippel, Arthur E. Bogan 



Reservoir middens or at Widows Creek (Warren 1975), and Morrison 

 (1942:359) listed A. grandis along with a few other species as being 

 "present in small numbers only, if represented by more than one speci- 

 men each." Leptodea fragilis (Raf. 1820) often reaches its greatest 

 abundance in habitat similar to that preferred by Anodonta. It now 

 occurs locally throughout the Tennessee River although, as evidenced 

 by recovery of only one valve of 60,350 collected at Widows Creek 

 (Warren 1975) and none from the Pickwick Basin and Chickamauga 

 Reservoir middens, it was extremely rare in prehistoric times. A single 

 valve of Potamilus alatus (Say 1817) occurred in the Middle Woodland 

 site midden and two shells in the multicomponent Middle/ Late Wood- 

 land site. It was not present at the Widows Creek site (Warren 1975), 

 and Morrison (1942) identified only "a few individuals" from the Pick- 

 wick Basin mounds. Potamilus alatus is another species that has adapted 

 to and flourishes in Tennessee River reservoirs. 



Viable populations of four other species now inhabiting the middle 

 and upper Tennessee River provide an interesting contrast with their 

 apparent prehistoric abundance and distribution. They are Ellipsaria 

 lineolata (Raf. 1820), Tritogonia verrucosa (Raf. 1820), Obliquaria 

 reflexa (Raf. 1820), and Megalonaias gigantea (Barnes 1823). All four 

 appear to have their center of origin in the Interior Basin or Mississippi 

 River drainages. Ellipsaria lineolata is presently relatively common in 

 the Chickamauga and Nickajack reservoirs (Pardue 1981). Ortmann 

 (1925) commented that it was rare in the upper Tennessee, and the pauc- 

 ity of shells from Pickwick Basin ("found only as scattered individuals 

 in two of the mounds"; Morrison 1942:361) and Widows Creek (one 

 valve), and no specimens from the Chickamauga Reservoir middens, 

 attest to its rarity in prehistoric times. Tritogonia verrucosa is another 

 species that has become established in the Chickamauga Reservoir, 

 apparently in modern times, as no shells of this mussel were found in 

 the midden samples we examined and it was not encountered by Warren 

 (1975) at the Widows Creek site or by Morrison (1942) in Pickwick 

 Basin mounds. 



Pardue (1981) reported taking M. gigantea at one station in the 

 Nickajack Reservoir at Chattanooga and from three localities in the 

 Chickamauga Reservoir. Like T. verrucosa, M. gigantea has become 

 established in the middle and upper reservoirs of the Tennessee River in 

 recent times. No specimens were encountered in the Pickwick Basin 

 mounds, at Widows Creek, or in the Chickamauga Reservoir middens. 

 Megalonaias gigantea may well continue to extend its range and in- 

 crease in abundance, since it seems to adapt well to a river-lake habitat. 

 For example, M. gigantea is the most abundant species in the im- 

 pounded stretches of the middle Cumberland River, Tennessee (Parma- 

 lee et al. 1980). The last of these four river species that has thrived and 



