Taxonomy of Pseudemyd Turtles 27 



comm.). This species is known to occur only in drainage basins of the 

 Atlantic slope (Conant 1975). Based on external morphology of the 

 New River specimens, Carl H. Ernst (pers. comm.) suggested possible P. 

 rubriventris influence in the population and the possibility of a P. flori- 

 dana x rubriventris hybrid swarm similar to that reported in North 

 Carolina by Crenshaw (1965). All that remained evident was that the 

 turtles collected from the New River at Bluestone Reservoir belong to 

 the subgenus Pseudemys (sensu McDowell 1964; Vogt and McCoy 

 1980). This subgenus includes P. floridana, P. concinna and a P. rubri- 

 ventris series of P. nelsoni Carr, P. alabamensis Baur and P. rubriventris. 

 The present study, which analyzes cranial structure, shell morphol- 

 ogy, color patterns and incidental natural history data, was designed to 

 evaluate the taxonomic position and probable origin of Pseudemys in 

 the New River. Although a systematic analysis of the subgenus Pseude- 

 mys was not the original or primary objective of the study, problematic 

 levels of speciation and questionable validity of traditional key charac- 

 ters necessitated comparisons with all taxa in the subgenus, especially 

 those with more northerly distributions. 



MATERIALS AND METHODS 



Twelve adult Pseudemys from the New River were examined and 

 morphologically compared to other forms of the subgenus Pseudemys. 

 The New River sample includes a specimen collected in Giles County, 

 Virginia, in 1975; seven individuals collected in Bluestone Reservoir in 

 May 1980; and the four specimens from Bluestone Reservoir described 

 by Bayless (1972). Weaver and Rose (1967) found shell depth, nuchal ( = 

 cervical) scute underlap, and gular scute overlap especially useful in 

 separating P. floridana, P. concinna, and P. nelsoni. These measure- 

 ments were taken on New River Pseudemys and initially calculated as 

 ratios following the methods of Weaver and Rose (1967) to allow direct 

 comparison to their data. For subsequent shell comparisons among 

 adult (153-300 mm carapace length) New River Pseudemys, P. rubriven- 

 tris, and northern subspecies of P. concinna and P. floridana (Fig. 3): 

 shell depth was calculated as a ratio of height to carapace length; gular 

 scute overlap was calculated as 10X the ratio of gular scute length (dor- 

 sal surface) to plastron length; and nuchal scute underlap was calculated 

 10X the ratio of cervical scute length (ventral surface) to carapace 

 length. Measurements were made with Helios or bow outside calipers. 

 Characters traditionally used by Carr (1952) and Crenshaw (1955), such 

 as patterns and coloration of head, neck, plastron and carapace, were 

 also analyzed. 



For phenetic analysis of adult cranial morphology, skulls from 4 

 Bluestone specimens were compared to skulls of 8 P. rubriventris, 4 P. 

 nelsoni, 3 P. alabamensis, 5 P. f. floridana, 6 P. f peninsularis, 1 3 P. f 

 hoyi, 5 P. c. concinna, 5 P. c. suwanniensis, 8 P. c. hieroglyphica, 9 P. c. 



