Necturus beyeri Viosca, 1937
Gulf Coast waterdog
© 2020 Craig Guyer (1 of 5)
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
Life History, Abundance, Activity, and Special Behaviors
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
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
Possible reasons for amphibian decline
General habitat alteration and loss
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).
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.
Originally submitted by: Meredith J. Mahone, Craig Guyer (first posted 2000-07-26)
Comments by: Michelle S. Koo (updated 2021-03-18)
Edited by: M. J. Mahoney, Ann T. Chang (2021-03-18)
Species Account Citation: AmphibiaWeb 2021 Necturus beyeri: Gulf Coast waterdog <https://amphibiaweb.org/species/4224> University of California, Berkeley, CA, USA. Accessed Nov 26, 2022.
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Citation: AmphibiaWeb. 2022. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 26 Nov 2022.
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