88 Stephen J. Walsh and Brooks M. Burr 



meridionale. Moreover, the means for number of infraoral cusps, inter- 

 mediate teeth in the anterior field, and inner lateral teeth in Kentucky 

 specimens of L. aepyptera, are closest to the means for these same char- 

 acters in L. meridionale (Vladykov et al. 1975, Table 11). Further, the 

 mean number of oral papillae and number of cusps (1 - 4) on the 

 median inner lateral teeth of Kentucky L. aepyptera are similar to the 

 means for L. aepyptera given by Vladykov et al. Thus, there is much 

 variation in the dentition of L. aepyptera. Individual variation, popula- 

 tional differences, and possibly ontogenetic changes in dentition, occur. 

 We therefore regard Lethenteron meridionale a synonym of Lampetra 

 aepyptera, a conclusion anticipated by Rohde (1980) and formally 

 stated by Bailey (1980). Okkelbergia (a monotypic genus including 

 aepyptera as its only species) and Lethenteron were recently down- 

 graded to subgenera of Lampetra (Bailey 1980), an action with which 

 we concur. 



Morphology of lampetra aepyptera 



The number of myomeres in L. aepyptera ranges from 50 to 62 

 (e.g., Branson 1970; Cook 1952; Raney 1941; Rohde 1976; Rohde et al. 

 1975, 1976; Seversmith 1953; Vladykov et al. 1975). Rohde et al. (1976) 

 found no significant difference in the number of myomeres between 

 ammocoetes and adults in Delaware. The number of myomeres of 

 adults in Kentucky ranged from 52 to 62 (Fig. 3), with means between 

 55 and 59 in all drainages except the lower Cumberland and Tennessee 

 rivers. The number of myomeres in 105 ammocoetes from Terrapin 

 Creek, Graves County, ranged from 51 to 59 (x = 55.0), slightly fewer 

 than for adults. However, the means of myomere counts are not signifi- 

 cantly different between ammocoetes and adults. Although visually 

 there appears to be an east to west decrease in the mean number of 

 myomeres (Fig. 3), one way analysis of variance indicates no significant 

 differences between the means of any of the drainages (a = 0.05). A tho- 

 rough study of specimens from throughout the entire range of L. aepyp- 

 tera is needed to determine possible significant variation in this or any 

 other morphological character. 



The most significant differences in body proportions of L. aepyp- 

 tera involved the partially transformed (neotenic) individuals from Ter- 

 rapin Creek (Obion River drainage). The secondary sexual characteris- 

 tics of nuptial adults (e.g., disc length, eye diameter, second dorsal fin 

 height, and prebranchial length; Table 1) were poorly developed in the 

 neotenes, Because individuals in Terrapin Creek fail to fully transform, 

 the discordant body proportion values exhibited by the population were 

 expected. The Cumberland River population from above Cumberland 

 Falls exhibited a relatively low proportional value for second dorsal fin 

 height. This population is geographically isolated and the low fin value 



