46 Ray E. Ashton, Jr., Alvin L. Braswell, Sheldon I. Guttman 
DISCUSSION 
Electrophoretic analysis of ten individuals from each of two popula- 
tions of N. maculosus and one individual from a third population showed 
that they were indistinguishable using this technique. Necturus lewisi and 
N. punctatus, however, were highly distinguishable from each other and 
from N. maculosus, indicating that each species has been genetically 
isolated for some time. Two populations of N. punctatus, the spotted 
form inhabiting the Sandhills region of North Carolina and the uni- 
formly gray-black form inhabiting the Neuse River, were in- 
distinguishable from each other. 
In conclusion, the specific status of N. lewisi is confirmed by elec- 
trophoretic data as well as by the distinct larvae described by Ashton and 
Braswell (1979). Further, N. punctatus appears to have been reproduc- 
tively isolated from sympatric N. lewisi and from allopatric N. maculosus 
for a considerable period of time, and spotted N. punctatus from the 
PeeDee River drainage (North and South Carolina) appear on the basis 
of electrophoresis to be genetically similar to the unspotted populations 
of the Neuse River system. 
ACKNOWLEDGMENTS. — The authors wish to express their ap- 
preciation to field technicians Angelo Capparella, Paul Freed, and Jerry 
Reynolds, and laboratory assistants Gary Trakshel, Kim Haikyong, and 
Ernie Flowers. We also thank John E. Cooper for his critical review of 
the manuscript. This project was in part supported by funds from a U.S. 
Fish and Wildlife Service (Office of Endangered Species) cooperative 
agreement with the North Carolina Wildlife Resources Commission. 
LITERATURE CITED 
Ashton, Ray E,, Jr, and A.L. Braswell. 1979. Nest and larvae of the Neuse River 
Waterdog, Necturus lewisi (Brimley) (Amphibia: Proteidae). Brimleyana 
7:15-22. 
Ayala, Francisco J., D. Hedgecock, G. Zumwalt and J. Valentine. 1973. Genetic 
variation in Tridacna maxima, an ecological analog of some unsuccessful 
evolutionary lineages. Evolution 27:177-191. 
Brewer, George. 1970. Introduction to isozyme techniques. Academic Press, 
New York. 186 pp. 
Brimley, Clement S. 1924. The Water Dogs {Necturus) of North Carolina. 
J. Elisha Mitchell Sci. Soc. 40(3-4): 166- 168. 
Nei, Masatoshi. 1972. Genetic distance between populations. Am Nat 
706:283-292. 
Selander, Robert K., M.H. Smith, S.Y. Yang, W.E. Johnson and J.B. Gentry. 
1971. Biochemical polymorphism and systematics in the genus Peromyscus. 
I. Variation in the old-field mouse {Peromyscus polionotus). Stud. Genet. VI. 
Univ. Texas Publ. 7103:49-90. 
Viosca, Percy, Jr. 1937. A tentative revision of the genus Necturus, with descrip- 
tions of three new species from the southern Gulf drainage area Copeia 
1937(2):120-138. 
Accepted 14 October 1980 
