Morphological and Ecological Comparisons Between Two Sibling Species of the Genus Desmognathus

Suitor, Jacqueline

Salamanders of the Desmognathus ochrophaeus complex exhibit considerable interpopulational and intrapopulational variability in dorsal color patterns particularly in the southwest Blue Ridge Physiographic Province. There are also interpopulational differences in habitat preference and body size. This has been the cause of considerable taxonomic instability and confusion. Two sibling species of this complex are known to occur in sympatry in the Great Smoky Mountains National Park. Electrophoretic analysis indicates that these species are genetically dissimilar. They can be distinguished by their different dorsal color patterns but this is difficult at some locations. This thesis is an attempt to locate morphological and ecological characters that can distinguish the two forms. The two species, here called "imitator" and "ochrophaeus", were found to have very similar skull morphology. Rate of loss of vomerine teeth in males was similar although "D. imitator" may lose teeth at a slower rate relative to testis lobe category. Small sample sizes make this inconclusive. The two species differ in body size. The "ochrophaeus" form is a larger species at sexual maturity and throughout development. There is no appreciable sexual dimorphism, but animals of both species are larger at Indian Gap (5200'-5000') than at Hughes Ridge (4200*-4000') in the Great Smoky Mountains. The exception is "ochrophaeus" females which are larger at Hughes Ridge and larger than "ochrophaeus" males at Hughes Ridge. This is believed to be an artifact of sampling. Females of the "ochrophaeus" species show a poor correlation between enlarged follicle size and SVL. This is different from "imitator" females which show a fairly high correlation which is consistent with reported trends in the genus Desmognathus. Microecological differences are much more pronounced than morphological differences. The "imitator" species is found throughout the Great Smokies at a wide range of elevations, but it is restricted to the Smokies. This form is found in both stream and woodland habitats, but the juveniles show a statistically significant preference for the stream habitat. The "ochrophaeus" species ia a woodland animal that is rarely found in the stream habitat. It is restricted to the high elevation ridge tops in the Smokies, but unlike "imitator" is found outside of the Great Smoky Mountains. Juveniles of this species were rarely encountered in the Great Smokies.