Description
Necturus beyeri is a neotenic species of aquatic salamander with adults reaching a standard length of up to 184.0 mm in males and 177.0mm in females. Average male snout-vent length is 134.2 mm and average female snout-vent length is 120.8 mm. Males reach sizes that average 13 mm longer in standard length than females. Maximum tail length in males is 68 mm and in females is 66 mm (Guyer et al. 2020). The body is near cylindrical (Neill 1963, Bart et al. 1997). This species is identified as a member of the family Proteidae by retention of external gills in adults, and the presence of four robust limbs with four toes on the hind limbs. Typically, seventeen costal grooves are present (range of 16 - 18). Reproductive males can be distinguished from adult females by the presence of a swollen cloaca, a cloacal lining of finger-like projections, and a spur-like tip on each side of the posterior end of the cloacal opening (Guyer et al. 2020). Tails of both sexes are laterally compressed (Petranka 1998).

Hatchling size is 13 - 16 mm snout to vent length (Shoop 1965).

Populations of Gulf Coast Waterdogs are most easily distinguished from populations of other species of Necturus by the larval coloration. The light spotting of N. beyeri, is not present in larvae of N. moleri and N. mounti, as well as some populations of N. punctatus. Larvae of N. alabamensis, N. lewisi, and N. maculosus possess larvae with dark middorsal or dorsolateral stripes not found in N. beyeri. Finally, the presence of large dark spots in larvae and adults of N. beyeri distinguish this species from N. punctatus, which typically lacks dark spotting.

In life, the dorsum and sides of adults is pinkish gray to tan, with numerous small, faded white spots and larger dark purple or black spots. The size and distribution of the dark spots varies geographically. Specimens from the Mobile and Pascagoula have relatively small dark spotting (spots about equal in size to size of eye) and typically lack midventral spotting. Those from west of the Mississippi River typically have large dark spots (larger than the size of eye) that extend on to the midventer. Specimens from the Pearl and Pontchartrain drainages are intermediate between these two extremes. In preservation, the dorsal ground color becomes slate brown with white spots. The head has dark-brown spots that are smaller anteriorly and larger dark brown spots posteriorly that extend onto the dorsum, sides of body, and tail. The chin has small brown spots along the mandibles but no spots in the middle of the chin. The ground color of the ventrum is uniformly tan with white ventrolateral spotting. Small brown spots are also present mid-ventrally and enlarge towards the lateral edges of the body (Guyer et al. 2020).

Larvae of Gulf Coast Waterdogs are pinkish gray with numerous small white spots covering the sides and dorsum. As they grow, dark spots appear and become prominent (Guyer et al. 2020).

The number of costal grooves ranges from 16 – 18, with most individuals having 17. Most individuals have large dorsal and lateral spotting but lack spotting on their snouts, chins, and ventrums. However, there are differences in spotting by geography with the Pearl lineage exhibiting a high proportion of individuals having snout spotting (63%), chin spotting (54%), and ventral spotting (56%); and the Mobile lineage exhibiting a high proportion of individuals having small dorsal spotting (54%), lacking chin spotting (93%), and lacking ventral spotting (84%). Reproductive males can be distinguished from adult females by the presence of a swollen cloaca, a cloacal lining of finger-like projections, and a spur-like tip on each side of the posterior end of the cloacal opening (Guyer et al. 2020).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: United States

U.S. state distribution from AmphibiaWeb's database: Alabama, Florida, Georgia, Louisiana, Mississippi

	View distribution map in BerkeleyMapper.
	View Bd and Bsal data (33 records).

Recent molecular analysis has partitioned N. beyeri into four lineages that range in the Gulf Coast Plain of the United States from Alabama to Texas. The Mobile lineage is restricted to the Mobile and Biloxi drainages in Alabama and Mississippi, respectively. The Pearl lineage is restricted to the Wolf and Pearl drainages in Mississippi and Louisiana, respectively. The Pontchartrain lineage is found in the Bayou Bonfouca to the Blind River, Louisiana. Lastly, the Western lineage can be found from the Calcasieu drainage in Louisiana, to the West Fork of the San Jacinto River in Texas. The type locality for the species is the Upper Calcasieu River at Oakdale, Allen Parish, Louisiana (Guyer et al. 2020).

Life History, Abundance, Activity, and Special Behaviors
Gulf Coast Waterdogs occur in slow-moving streams where they may occupy undercut banks, overhanging stumps, sunken logs, rocks, or accumulated piles of submerged leaf litter (Gunter and Brode 1964). These salamanders may be collected by dipnets, minnow traps (Brenes and Ford 2006), or by use of litter bags (Lamb and Qualls 2013) and frequently are associated with larvae of Eurycea cirrigera, E. quadridigitata, and Desmognathus conanti (Guyer et al. 2020).

Necturus beyeri have been reported to swim in the water column when they are active (Neill 1963). Mudpuppies and waterdogs are nearly inactive in the summer, and individuals are rarely found (Petranka 1998). Animals caught in the autumn may be quite lean compared with their condition in the winter and spring when they are in reproductive readiness (Bart et al. 1997).

Adult Gulf Coast Waterdogs are most likely to be detected in winter months (November – January), when mating occurs (Shoop 1965). Fertilization occurs via transfer of a spermatophore deposited by a male to a female who picks it up with her cloacal lips. Fertilized eggs are retained within a female’s uterus until the clutch is deposited in April or May. Nest sites are found under rocks, logs or other sunken objects where 26 - 37 eggs are laid, and the female attends the clutch (Sever and Bart 1996). Hatching occurs about two months after oviposition (Shoop 1965). After hatching, larvae can be sampled from leaf packs, eventually reaching adult size in 4 - 6 years (Bart and Holzenthal 1985).

Larvae and adults eat isopods, midges, mayflies, and caddisflies (Bart and Holzenthal 1985).

Predators likely include fishes, aquatic snakes, and crabs (Gunter and Brode 1964, Petranka 1998).

Gulf Coast Waterdogs may be infested with acanthocephalan parasites, for which waterdogs are a definitive host (Bart and Holzenthal 1985). Additionally, N. beyeri individuals from southeast Louisiana have tested positive for Batrachochytrium dendrobatidis (Glorioso et al. 2017; see “Trends and Threats” below).

Trends and Threats
Petranka (1998) speculates that numbers of Gulf Coast Waterdogs likely have been reduced due to siltation and pollution.

Batrachochytrium dendrobatidis (Bd) and B. salamandrivorans (Bsal) have been sampled from N. beyeri in southeast Louisiana. There was an overall Bd prevalence of 43% in the species, but they were present at low pathogen levels and infected individuals did not show clinical signs. No individuals tested positive for Bsal, and as of 2020, the susceptibility of N. beyeri to Bsal is still unknown (Glorioso et al. 2017).

Relation to Humans
Mudpuppies and waterdogs are sometimes seen in the pet trade.

Possible reasons for amphibian decline

General habitat alteration and loss
Local pesticides, fertilizers, and pollutants

Comments
The species authority is: Viosca, P. Jr. (1937). “A tentative revision of the genus Necturus with descriptions of three new species from the southern Gulf drainage area." Copeia. 1937:120–138. doi:10.2307/1436953.

Based on Bayesian Inference of ND2 mtDNA, N. beyeri is paraphyletic. More analysis is needed to determine if N alabamensis, N. beyeri and/or N. maculosus are a single meta population or if this clade is composed of more cryptic species (Chabarria et al. 2017, Guyer et al. 2020).

The species epithet, “beyeri”, is in honor of George E. Beyer, who in the early 1900s was a naturalist at Tulane University and contributed to the knowledge of herptofauna in the state of Louisana (Guyer et al. 2020).

References

Bart, H. L., Jr., Bailey, M. A., Ashton, R. E., Jr., and Moler, P. E. (1997). ''Taxonomic and nomenclatural status of the Upper Black Warrior River Waterdog.'' Journal of Herpetology, 31, 192-201.

Bart, H.L., Jr., Holzenthal R.W. (1985). ''Feeding ecology of Necturus beyeri in Louisiana.'' Journal of Herpetology, 19(3), 402-410. [link]

Brenes, R., Ford N.B. (2006). ''Seasonality and movements of the Gulf Coast Waterdog (Necturus beyeri) in eastern Texas.'' Southwestern Naturalist , 51(2), 152-156. [link]

Glorioso, B.M., Waddle, J.H., Richards-Zawacki, C.L. (2017). ''Prevalence of Batrachochytrium dendrobatidis and B. salamandrivorans in the Gulf Coast Waterdog, Necturus beyeri from southeast Louisiana, USA.'' Herpetological Review, 48(2), 360-363. [link]

Gunter G., Brode W.E. (1964). ''Necturus in the state of Mississippi, with notes on adjacent areas.'' Herpetologica, 20(2), 114-126. [link]

Lamb, J.Y., Qualls, C.P. (2013). ''Necturus beyeri (Gulf Coast Waterdog): Detection by leaf litter bag.'' Herpetological Review, 44(3), 491. [link]

Neill, W. T. (1963). "Notes on the Alabama waterdog, Necturus alabamensis Viosca." Herpetologica, 19, 166-174.

Petranka, J. W. (1998). Salamanders of the United States and Canada. Smithsonian Institution Press, Washington D.C. and London.

Sever, D. M., and Bart, H. L., Jr. (1996). ''Ultrastructure of the spermathecae of Necturus beyeri (Amphibia: Proteidae) in relation to its breeding season.'' Copeia, 1996(4), 927-937.

Shoop, C. R. (1965). "Aspects of reproduction in Louisiana Necturus populations." American Midland Naturalist, 74, 357-367.

Species Account Citation: AmphibiaWeb 2021 Necturus beyeri: Gulf Coast Waterdog <https://amphibiaweb.org/species/4224> University of California, Berkeley, CA, USA. Accessed Jan 24, 2025.

Citation: AmphibiaWeb. 2025. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 24 Jan 2025.

AmphibiaWeb's policy on data use.