PROC. BIOL. SOC. WASH. 93(2), 1980, pp. 339-345 RELATIONSHIPS BETWEEN NORTH AMERICAN TURTLES OF THE CHRYSEMYS COMPLEX AS INDICATED BY THEIR ENDOPARASITIC HELMINTHS Carl H. Ernst and Evelyn M. Ernst Abstract. — Comparisons of the similarity indexes of helminth faunas par-asitizing North American species of the turtle genera Chrysemys, Pseud-emys, and Graptemys indicate that these turtles represent three separate genera. Pseiidemys species apparently are not congeneric with Chrysemys picta as suggested by other studies. Also, the species of Graptemys appear more closely related to Pseudemys than to Chrysemys picta. McDowell (1964) revised the New World emydine genus Chrysemys on the basis of skull and foot morphology, including in it C. picta and the slider turtles of the genus Pseudemys, and suggested that three subgenera were involved {Chrysemys, Pseudemys, and Trachemys). Similarities in the choanal structure of Chrysemys picta and various species of Pseudemys upheld both the placement of the Pseudemys within the genus Chrysemys and McDowell's subgeneric distinctions (Parsons 1968). Zug (1966) found little variation in the penial structure of Chrysemys picta and Pseudemys scripta, P. nelsoni, P. floridana, and P. concinna, strengthening the inclu-sion of these turtles within Chrysemys. Weaver and Rose (1967) concurred with the inclusion of Pseudemys in Chrysemys, but showed the subgenera to be invalid, basing this on further examination of skull and shell charac-ters. Ernst and Barbour (1972), Conant (1975), and the Testudines Section of the Catalogue of American Amphibians and Reptiles (Society for the Study of Amphibians and Reptiles), of which the senior author is editor, recognize Graptemys and Chrysemys. There remains much disagreement about the generic arrangement of these turtles and many experts still maintain that Pseudemys is a separate genus. Recently, Holman (1977) expressed doubts about the status of Mc-Dowell's (1964) genus Chrysemys. Holman points out that under Mc-Dowell's concept as many as four species may occur in the same water body in the southeastern United States and that, although they have similar courtship patterns, there are no records of hybridization between Chryse-mys picta and other species of Chrysemys. However, hybrids are known within the subgenus Pseudemys: C. floridana x C. concinna (Smith, 1961)
BioStor
