Distribution, Morphology and Life History 



of the Least Brook Lamprey, 



Lampetra aepyptera (Pisces: Petromyzontidae), in Kentucky 



Stephen J. Walsh and Brooks M. Burr 



Department of Zoology, 



Southern Illinois University at Carbondale, 



Carbondale, Illinois 62901 



ABSTRACT.— Kentucky distribution records for the least brook 

 lamprey, Lampetra aepyptera (Abbott), show that it is the most 

 abundant and widespread lamprey in the state, inhabiting most major 

 drainages where suitable habitat is available. Morphological and denti- 

 tion data from over 220 specimens reveal that the recently described 

 Lethenteron meridionale, from Tennessee, Alabama and Georgia, is a 

 synonym of L. aepyptera. Interdrainage variation in meristic and mor- 

 phometric characters of L. aepyptera falls within the normal range of 

 variability for the species in the Ohio Valley. 



INTRODUCTION 



Although a considerable distributional and ecological literature 

 exists for the least brook lamprey, Lampetra aepyptera (Abbott), little 

 information has been published on its occurrence and life history in 

 Kentucky. A few distributional records for the species in Kentucky were 

 reported by Branson (1970), Burr and Mayden (1979), Burr (1980), and 

 Clay (1975). The only information on its natural history in the state was 

 summarized by Clay (1975), who included original observations on the 

 demise of a population in Knob Creek, southwest of Louisville. The 

 most complete studies on the life history of L. aepyptera were done in 

 Maryland (Seversmith 1953) and Delaware (Rohde et al. 1976). Branson 

 (1970), Clay (1975), and Clay and Carter (1957) briefly described its 

 morphological characteristics in Kentucky. In their description of 

 Lethenteron meridionale, Vladykov et al. (1975) gave the most complete 

 morphological description of L. aepyptera to date. Rohde et al. (1976) 

 summarized meristic and morphometric characteristics of the species in 

 Delaware and the literature prior to their study. 



The purposes of this paper are to (1) map and describe the Ken- 

 tucky distribution of L. aepyptera, (2) analyze its morphological charac- 

 teristics in the state, and (3) supplement published ecological informa- 

 tion with our observations of what appears to be a neotenic population 

 in western Kentucky, a heretofore unreported phenomenon in this spe- 

 cies. The discovery of posterior circumoral teeth in a number of Ken- 

 tucky L. aepyptera, and the variability of their presence, leaves little 

 doubt that Lethenteron meridionale is a synonym of Lampetra 

 aepyptera. 



Brimleyana No. 6: 83-100. December 1981. 83 



