A New Cryptic Species of Salamander of 



the Genus Plethodon from the 



Southeastern United States 



(Amphibia: Plethodontidae) 



Richard Highton 



Department of £00 logy, University of 

 Maryland, College Park, Maryland 20742 



ABSTRACT. — A new species of woodland salamander, Plethodon 

 websteri, is described. It is a member of the P. welleri group of eastern 

 small plethodons and is morphologically very similar to P. dorsalis, but 

 differs from it at over 80% of 26 genetic loci as determined by elec- 

 trophoresis. This represents an extreme case of genetic divergence 

 without accompanying morphological change. The geographic range of 

 P. websteri includes east central Alabama and west central Georgia with 

 disjunct populations in Clarke County, Alabama; Winston County, 

 Mississippi; and McCormick County, South Carolina. The ranges of P. 

 dorsalis and P. websteri are largely allopatric, but the two have been found 

 sympatrically at one locality in Jefferson County, Alabama. 



An electrophoretic study of genetic variation in salamanders of the 

 Plethodon welleri group (Larson and Highton 1978) showed that an un- 

 described species occurs in Mississippi, Alabama, Georgia and South 

 Carolina. Morphologically it is so similar to Plethodon dorsalis Cope that 

 there are no known standard taxonomic characters that distinguish the 

 two species. Yet genetically they are so different that they share less than 

 20% of their alleles at the 26 genetic loci evaluated electrophoretically. 

 Thus they represent a most extraordinary example of evolutionary 

 genetic divergence without accompanying morphological change. 



There is no doubt of the specific distinctness of the two species. They 

 differ genetically from each other more than do some genera, for example 

 Notophthalmus and Tancha (Ayala 1975). They have been taken sym- 

 patrically in Jefferson County, Alabama, and no electrophoretic hybrids 

 were detected. The absence of diagnostic morphological characters re- 

 quires that the species be diagnosed exclusively on the basis of elec- 

 trophoretically detectable differences in the mobility of protein molecules. 

 This makes it difficult to identify living or preserved salamanders. For- 

 tunately, the ranges of the two species appear to be largely allopatric so 

 that most individuals may be identified on the basis of geographic 

 provenance. Moreover, in and near the zone of contact between the two 



Brimleyana No. 1: 31-36. March 1979. 31 



