Chickamauga Reservoir Mussels 85 



by those of Q. pustulosa; both species still occur as viable populations 

 in the Chickamauga Reservoir, apparently having adapted to 

 impoundment conditions. Both Q. cylindrica (1817) and Q. intermedia 

 (Conrad 1836) are apparently now extirpated in the upper Tennessee 

 River; judging by the relatively few specimens obtained in the middens, 

 both were uncommon in prehistoric times. Today, limited populations 

 of Q. intermedia, a "Cumberlandian" species that typically inhabits 

 small-to-medium size rivers, occur in the upper Powell and Clinch rivers 

 of northeast Tennesseee and in the Duck River of Middle Tennessee. In 

 prehistoric times, however, the species occurred throughout the upper 

 and middle Tennessee River; Morrison (1942) reported it present but 

 not common in Pickwick Basin shell mounds, northwestern Alabama. 

 Amblema plicata (Say 1817), a species now relatively common in the 

 Chickamauga Reservoir (Pardue 1981), appears to have been uncom- 

 mon to rare in prehistoric times (valves comprised < 0.5% of the total). 



The combined number of valves (477) of the three species of Pleth- 

 obasus constituted less than 2% of the total. However, valves occurred 

 in all cultural components, but the low numbers apparently reflect their 

 limited abundance in the upper Tennessee during the last 2000 years. At 

 the Widows Creek site they comprised less than 3% of the total (Warren 

 1975), and Morrison (1942) reported only a few specimens of P. 

 cyphyus and P. cicatricosus (Say 1829) and none of P. cooperianus 

 from the Pickwick Basin middens. Ortmann (1925:338) commented that 

 P. cyphyus occurred sparingly in the main river in the lower Tennessee 

 drainage, while P. cooperianus "goes into the upper Tennessee up to the 

 Knoxville region, but it is rare there." Although P. cicatricosus was 

 recorded from below Wilson Dam by Stansbery (1964), it is now near- 

 ing extinction and is represented by a few old relic individuals. Based on 

 a few valves recovered from shelter's cull piles (taken in the early 1970s), 

 P. cyphyus appears to continue to survive in the Chickamauga Reser- 

 voir. One valve of P. cooperianus was also found in a cull pile. 

 Although Scruggs (1960) recorded it from the Washington Ferry area 

 (TRM 518), Pardue (1981) failed to find it anywhere in the middle or 

 upper reaches of the Chickamauga Reservoir. 



One of the most interesting naiad assemblages represented in the 

 Chickamauga Reservoir middens consists of 12 species belonging to the 

 genus Plagiola (-Dysnomia-Epioblasma) (Johnson 1978). Six of these 

 (arcaeformis Lea \S34,flexuosa Raf. 1820, haysiana Lea 1834, propin- 

 qua Lea 1857, stewardsoni Lea 1852, turgidula Lea 1858) are now 

 extinct. Five others (capsaeformis Lea \834, florentina Lea 1834, torul- 

 osa Raf. 1820, interrupta Lea 1831, obliquata Raf. 1820) are either 

 extremely rare, or their former ranges have been reduced to a few local- 

 ized habitats, or both. All of those species inhabit (or did inhabit) small- 

 to-medium size rivers, or the shallow riffle and shoal areas of large riv- 



