106 Michael E. Seidel and William M. Palmer 



evidence of hybridization has been reported. Some populations with 

 intermediate (hybrid?) characters are geographically broad, which 

 suggests subspecific relationships. These interactions have been examined 

 in Florida (Crenshaw 1955) and Louisiana (Fahey 1980). Part of the 

 problem has arisen from the absence of clearly defined quantifiable 

 characters that separate species of Pseudemys. Another problem has 

 been the relatively small number of specimens examined, especially 

 from northern populations. The most recent taxonomic analysis with 

 species diagnoses of Pseudemys relies heavily on cranial musculature 

 and osteology (Ward 1984). Unfortunately those characters are of little 

 use in field identification or in evaluation of fluid-preserved museum 

 material. 



In spite of the taxonomic attention Pseudemys has received, we 

 have found that species of the eastern United States (Atlantic slope) 

 remain very difficult to identify using available diagnostic characters. 

 Nearly all key characteristics are qualitative and based on highly 

 variable markings and shell shapes. The problem of identification is 

 especially acute in the coastal plain of Virginia and North Carolina 

 where the ranges of P. rubriventris, P. concinna concinna, and P. 

 floridana floridana overlap or come in contact. In that area Crenshaw 

 (1965) noted putative hybridization between P. rubriventris and P. 

 floridana, and Martof et al. (1980) reported frequent hybridization 

 between P. concinna and P. floridana, commenting that some specimens 

 defy classification at the species level. The objectives of the present 

 study were: (1) to identify external characters that more reliably 

 distinguish these turtles in Virginia and North Carolina, (2) to identify 

 individual turtles from this region that appear to be morphologically 

 intermediate, and (3) to characterize patterns of Pseudemys distribution 

 in the central Atlantic coastal plain. 



METHODS 



For morphometric analysis, 76 fluid-preserved P. rubriventris (New 

 Jersey, Pennsylvania, West Virginia, Virginia, North Carolina), 57 P. c. 

 concinna (Virginia, North Carolina, South Carolina), and 59 P. f 

 floridana (Virginia, North Carolina, South Carolina) were analyzed 

 (Fig. 1). Specimens included freshly collected individuals with typical 

 coloration as well as museum, specimens (see Specimens Examined). 

 Abbreviations for museums follow Leviton et al. (1985), and MES = 

 reference collection of the senior author. All turtles were tentatively 

 identified to species a priori using traditional qualitative characters 

 (mostly markings, see Table 1) that have been applied to distinguish P. 

 concinna, P. floridana, and P. rubriventris (Ernst and Barbour 1972, 

 1989, Conant and Collins 1991). If assignment was questionable, that 



