Kentucky Mollusk Distributions 141 



Gastropoda: Prosobranchia 



Many taxonomic problems still exist among the Pleuroceridae, 

 problems that must be resolved before there is any stability in the family 

 at the species level. Not all of these problems can be resolved by means 

 of shell morphology. Instead, investigators must rely on data from 

 reproductive behavior, particularly the method of egg deposition, and 

 from newer techniques such as electrophoresis. In particular, there is a 

 plethora of problems needing resolution in the Cumberland and Green 

 rivers of Kentucky and adjacent Tennessee. To complicate matters, sev- 

 eral of the species are becoming threatened as we extend domination 

 over progressively larger and larger sections of those streams (Branson 

 et al. 1981). However, in spite of these problems, most of the genera 

 treated in Goodrich (1940) and elsewhere, with some exceptions, are 

 relatively stable and recognizable categories. The generic designations 

 used herein are principally those of Goodrich (1940). 



Pleuroceridae 



Lithasis obovata (Say). Collections: 1 (1), 2 (10), 27 (2), 45 (1). Not 

 a common species in general riverine collections from Kentucky, this 

 snail is listed as of Special Concern (Branson et al. 1981). There is an 

 apparently healthy population in the pool behind Lock 4 (our Station 2) 

 on the Kentucky River. There is a move by the U.S. Army Corps of 

 Engineers to abandon management and operation of the lock and dam 

 system, although some of the county governments along the river have 

 proposed to take over operating some of the individual locks. These 

 habitats may thus eventually become excellent areas for mollusks and 

 small fishes. 



Lithasia plicata Wetherby. Collections: 39 (1). Although not listed 

 as Threatened or Endangered, this species is rare in Kentucky waters 

 and probably deserves such consideration. It cannot withstand settleable- 

 solid or acid-mine pollution. Unfortunately, most of the known Ken- 

 tucky habitats lie in the middle of the Eastern Coal Fields. 



Pleurocera canaliculatum (Say). Collections: 2 (5), 4 (1), 5 (1), 10 

 (1), 24 (1), 45 (11). Most of these specimens are of the morphological 

 type listed under the subspecific designation P. c. undulatum (Say), 

 except those from the Licking River. The population at Station 4 is 

 large. 



Pleurocera acuta Rafinesque. Collections: 7(1), 17 (1), 18 (1), 31 

 (2), 33 (2), 39 (1), 40 (21), 50 (2). Pleurocera acuta is listed as of Special 

 Concern (Branson et al. 1981), although there is a healthy population at 

 Station 45 in the Licking River. The species has nearly disappeared 

 from localities where it was abundant (see Goodrich 1940; Call 1900). 



Nitocris trilineata (Say). Collections: 45 (5). Since we made this 



