Taxonomy of Pseudemyd Turtles 39 



Moreover, Ewert (1979) demonstrated that, at least in map turtles of the 

 genus Graptemys, diagnostic head markings may be altered by varying 

 incubation temperatures and therefore are not entirely under genetic 

 control. Nevertheless, the taxonomic arrangement of Crenshaw (1955), 

 although never published with full supporting documentation, has gen- 

 erally been followed (Conant 1961, 1975; Ernst and Barbour 1972; 

 Wermuthand Mertens 1961, 1977). 



Fahey (1980) proposed that P. concinna once again be placed in the 

 synonymy of P. floridana, a conclusion based exclusively on examina- 

 tion of turtles from Louisiana. Although Fahey's results suggest the 

 presence of a single species in the restricted region of his study, they 

 certainly do not substantiate relationships throughout the ranges of P. 

 floridana and P. concinna. In addition to Fahey's report, there are 

 numerous published references to either weak morphological separation 

 or putative hybridization between P. floridana and P. concinna in the 

 Mississippi Valley and areas to the west (Brown 1950; Smith 1961; An- 

 derson 1965; Webb 1970; Barbour 1971; Minton 1972; Mount 1975). 

 Traditional key characters, such as plastral markings and a "C" figure 

 on the second pair of pleurals, which are used to distinguish P. concinna 

 from P. floridana, are not consistent for central and western popula- 

 tions that are seemingly convergent in some characters. Ward (1980) 

 found no cranial characters with which he could separate the midwes- 

 tern subspecies P. f. hoyi and P. c. hieroglyphica and placed them in 

 synonymy. My results from discriminant analysis of cranial morphology 

 (Figs. 4, 5, and 6) support that decision. However, conclusions regard- 

 ing conspecific status for all turtles assigned to P. concinna and P. flori- 

 dana, especially eastern forms, must await a comprehensive and geogra- 

 phically broad analysis. 



Based on shell markings and proportions, overall pigmentation, 

 and cranial morphology, New River Pseudemys are clearly distinct from 

 P. rubriventris. The emarginate tomial surface of New River specimens 

 (Fig. 2) might be interpreted as a weakly developed notch bordered by 

 cusps, characteristic of species in the rubriventris series (Carr 1952; 

 Ernst and Barbour 1972). Weak cusps, however, have been reported in 

 several populations of cooters allopatric and sympatric with redbelly 

 turtles (Carr 1952; Crenshaw 1955; and personal examination of skulls: 

 CM 60560, UMMZ 127058, MCZ 54680). Furthermore, prominent 

 cusps are typical in P. c. texana (Ernst and Barbour 1972). Jackson 

 (1978) cautioned that little taxonomic weight should be given to trophic 

 structures in Pseudemys. The overall similarity in cranial morphology of 

 P. c. texana, P. nelsoni, and P. rubriventris (Fig. 4) may represent con- 

 vergence of character states resulting from similar feeding habits. 



A shallow carapace with evidence in some individuals of a "C" on 

 pleural II, and extensive dark markings on plastral, axillary and ingui- 

 nal scutes, are characteristics of New River cooters that justify their 



