Completely aquatic and gilled throughout life. The dwarf waterdog is the smallest member of the genus Necturus, which includes waterdogs and mudpuppies. All mudpuppies and waterdogs have bushy external gills, two gill slits, a laterally compressed tail, and four toes on front and hind feet. Adult dwarf waterdogs are 11.5-19 cm total length, and the tail is slightly less than 40% of total length. Sexually mature males can be distinguished by the swollen cloaca and pair of enlarged cloacal papillae that project posteriorly. Females have a proportionally longer tail than males. Coloration is generally a uniform slate gray to brown or dark olive above, normally without spots. Ventral color is dirty white and without spots, although a few may encroach at the edges of the venter. Dorsal spots are seen in some North Carolina populations. Spotted N. punctatus may be distinguished from the spotted N. lewisi by differences in size (N. lewisi is larger) and ventral coloration (N. punctatus has an unspotted venter, while N. lewisi is spotted). Also, spotted N. punctatus do not co-occur with N. lewisi. Hatchlings are uniformly brown dorsally, without stripes seen in other juvenile Necturus, like N. maculosus (Dundee 1998; Petranka 1998).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: United States
U.S. state distribution from AmphibiaWeb's database: Georgia, North Carolina, South Carolina, Virginia
Distributed in the Coast Plain from southeastern Virginia to south central Georgia, and also enters the Fall Line and Piedmont from North Carolina to Georgia. Prefers small and medium-sized streams, swamps, and pools, with vegetation and leafbeds (Meffe and Sheldon 1987; Dundee 1998; Petranka 1998).
Life History, Abundance, Activity, and Special Behaviors
Little is known about many life history features of dwarf waterdogs. Mating likely occurs in winter. Oviposition takes place in spring (Meffe and Sheldon 1987; Petranka 1998). Nests have not been described but are likely to be similar to other species of Necturus, where eggs are attached singly to the undersides of submerged cover objects (e.g. Shoop 1965; Ashton and Braswell 1979). Diet is similar to N. lewisi where these species co-occur (Braswell and Ashton 1985), and competition for food is possible. Diet items include oligochaetes, cladocerans, copepods, caddisflies, snails, clams, salamanders, and crayfish (Braswell and Ashton 1985; Meffe and Sheldon 1987; Petranka 1998). Natural predators have not been reported, but likely include fish (Petranka 1998).
Trends and Threats
Populations are apparently doing well, but pollution and siltation are harmful to these animals (Petranka 1998).
Relation to Humans
Mudpuppies and waterdogs are sometimes seen in the pet trade.
Necturus punctatus and N. lewisi may be sister species (Guttman et al. 1990).
Ashton, R. E., Jr., and Braswell, A. L. (1979). ''Nest and larvae of the Neuse River Waterdog, Necturus lewisi (Brimley) (Amphibia: Proteidae).'' Brimleyana, 1, 15-22.
Braswell, A. L., and Ashton, R. E., Jr. (1985). ''Distribution, ecology, and feeding habits of Necturus lewisi (Brimley).'' Brimleyana, 10, 13-35.
Dundee, H. A. (1998). ''Necturus punctatus (Gibbes). Dwarf Waterdog.'' Catalogue of American Amphibians and Reptiles. Society for the Study of Amphibians and Reptiles, 663.1-663.5.
Guttman, S. I., Weigt, L. A., Moler, P. E., Ashton, R. E., Jr., Mansell, B. W. and Peavy, J. (1990). ''An electrophoretic analysis of Necturus form the southeastern United States.'' Journal of Herpetology, 24(2), 163-175.
Meffe, G. K., and Sheldon, A. L. (1987). ''Habitat use by dwarf waterdogs (Necturus punctatus) in South Carolina streams, with life history notes.'' Herpetologica, 43, 490-496.
Petranka, J. W. (1998). Salamanders of the United States and Canada. Smithsonian Institution Press, Washington and London.
Shoop, C. R. (1965). "Aspects of reproduction in Louisiana Necturus populations." American Midland Naturalist, 74, 357-367.
Written by Meredith J. Mahoney (molge AT yahoo.com), Museum of Vertebrate Zoology, UC Berkeley
First submitted 2000-07-27
Edited by M. J. Mahoney (2001-05-09)
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