Tuesday, January 22, 2013

Species Profile: Tennessee Cave Salamander (Gyrinophilus palleucus)

Adult, Jackson Co., Alabama (Photo by Dante Fenolio)
Tennessee Cave Salamander
Gyrinophilus palleucus


Conservation Status: IUCN Red List - Vulnerable B2ab(iii,iv); NatureServe - GSG3 (Alabama: S2, Georgia: S1, Tennessee: S2). This species is 'Protected' in Alabama, 'Threatened' in Georgia, and 'Threatened' in Tennessee.

Description: Gyrinophilus palleucus is one of the four species of cave-obligate salamanders found east of the Mississippi River in the United States. They are large, aquatic salamanders that can reach lengths of 210 mm. Unlike most species of salamanders, Gyrinophilus palleucus does not readily undergo metamorphosis and attains sexual maturity in the larval stage. Consequently, they retain the conspicuous paired gills located on each side of the back of the head throughout life. Adults have a broad head with a flattened, shovel-like snout. They eyes are reduced in size compared to related surface-dwelling cousins like the Spring Salamander (G. porphyriticus) and Red Salamander (Pseudotriton ruber), but they are not completely degenerate as observed in other obligate cave-dwelling salamanders. However, some adults may have skin that completely covers their eyes. Also unlike other cave salamanders, G. palleucus is distinctly pigmented and ranges in color from pale pink and lacking spotting to dark reddish purple or brown with distinct spots or blotches on the back. Adults also have a series of unpigmented dots that represent pores of the lateral line system on the head and along the sides of the body that are used to detect moving prey, conspecifics and potential predators in their aquatic environment. Juveniles generally resemble adults but are much paler, lack conspicuous spots or blotches, and possess eyes that are proportionally larger relative to head size. Two subspecies are recognized: the Pale Salamander (G. p. palleucus) and the Big Mouth Cave Salamander (G. p. necturoides). These subspecies differ in coloration, relative eye size and number of trunk vertebrae but are thought to hybridize throughout much of northern Alabama.

Juvenile, Jackson Co., Alabama
Distribution: Gyrinophilus palleucus has been reported from 80 localities in northern Alabama (39 caves), northwestern Georgia (2 caves) and central Tennessee (38 caves and 1 spring). Its distribution includes caves in the Inner Nashville Basin, Eastern Highland Rim and escarpments of the Cumberland Plateau.

Habitat: Both adults and juveniles are most often observed resting on the bottom of shallow pools in the dark zone of subterranean streams but are also can be found in riffles and rimstone pools. They are most often found underneath rocks or within mats of organic debris washed into caves. Gyrinophilus palleucus has been found within the twilight zone of caves on occasion and at least one report was from a surface spring after heavy rainfall.

Adult, Coffee Co., Tennessee (Photo by Matthew L. Niemiller)
Natural History: Little is known about the life history and ecology of G. palleucus. This is particularly true for aspects of reproductive biology. Eggs have never been found, although it is presumed that mating and egg-laying occurs from autumn to early winter. Although data are limited, it appears that G. palleucus is long-lived and may take 5-8 years to reach sexual maturity. Tennessee Cave Salamanders are one of the top predators in the cave systems they inhabit. They will eat almost anything that will fit into their mouths, including isopods, amphipods, worms, small crayfish, and even smaller conspecifics. Metamorphosis is rare in the wild, but G. palleucus can be induced to metamorphose in the lab.

Adult, Warren Co., Tennessee (Photo by Matthew L. Niemiller)
Conservation: Populations of G. palleucus face a number of threats, such as habitat degradation, groundwater pollution, and alteration of water flow and organic input into cave systems associated with urbanization, mining, silviculture, agriculture, and the construction of dams. However, it is unclear what negative impacts these threats have had on populations of G. palleucus. Several populations studied appear to be stable and are under no immediate threat of extirpation. Moreover, recent surveys have revealed that the species is more widespread and abundant than previously believed. The entrances to several cave systems inhabited by G. palleucus are owned or managed by state or federal agencies or cave conservation organizations, which affords some protection.

Fun Fact: The Tennessee Cave Salamander is officially recognized as the state amphibian of Tennessee.

Select References

Beachy CK. 2005. Gyrinophilus palleucus. Pp. 775-776 in Lannoo M (ed.). Amphibian Declines: The Conservation Status of United States Species. University of California Press, Berkeley.

Brandon RA. 1966. Systematics of the salamander genus Gyrinophilus. Illinois Biological Monograph 35: 1-85.

Brandon RA. 1967. Food and intestinal parasite of the troglobitic salamander Gyrinophilus palleucus necturoides. Herpetologica 23: 52-53.

Brandon RA. 1971. North American troglobitic salamanders: some aspects of modification in cave habitats, with special reference to Gyrinophilus palleucus. Bulletin of the National Speleological Society 33: 1-21.

Godwin JC. 2008. Tennessee cave salamander. Gyrinophilus palleucus. Pp. 202-204 in Jensen JB, Camp CD, Gibbons W, Elliott MJ (eds.). Amphibians and Reptiles of Georgia. University of Georgia Press, Athens.

Goricki S, Niemiller ML, Fenolio DB. 2012. Salamanders. Pp. 665-676 in White WH, Culver DC (eds.). Encyclopedia of Caves. 2nd edition. Elsevier.

Huntsman BM, Venarsky MP, Benstead JP, Huryn AD. 2011. Effects of organic matter availability on the life history and production of a top vertebrate predator (Plethodontidae: Gyrinophilus palleucus) in two cave streams. Freshwater Biology 56: 1746-1760.

Lazell JD, Brandon RA. 1962. A new stygian salamander from the southern Cumberland Plateau. Copeia 1962: 300-306.

McCrady E. 1954. A new species of Gyrinophilus (Plethodontidae) from Tennessee caves. Copeia 1954: 200-206.

Miller BT, Niemiller ML. 2008. Distribution and relative abundance of Tennessee cave salamanders (Gyrinophilus palleucus and Gyrinophilus gulolineatus) with an emphasis on Tennessee populations. Herpetological Conservation and Biology 3: 1-20.

Miller BT, Niemiller ML. 2011. Tennessee cave salamander. Gyrinophilus palleucus. Pp. 175-178 in Niemiller ML, Reynolds RG (eds). The Amphibians of Tennessee. University of Tennessee Press, Knoxville.

Mount RH. 1975. The Reptiles and Amphibians of Alabama. University of Alabama Press, Tuscaloosa.

Niemiller ML, Fitzpatrick BM, Miller BT. 2008. Recent divergence with gene flow in Tennessee cave salamanders (Plethodontidae: Gyrinophilus) inferred from gene genealogies. Molecular Ecology 17: 2258-2275.

Niemiller ML, Miller BT, Fitzpatrick BM. 2009. Systematics and evolutionary history of subterranean salamanders of the genus Gyrinophilus. Proceedings of the International Congress of Speleology, Kerrville, Texas 15: 242-248.

Petranka JW. 1998. Salamanders of the United States and Canada. Smithsonian Institution Press, Washington.

Yeatman HC, Miller HB. 1985. A naturally  metamorphosed Gyrinophilus palleucus from the type-locality. Journal of Herpetology 19: 304-306.

1 comment:

  1. Excellent information about a fascinating species. Read your paper in PDF format concerning these animals and found it very informative. I was especially interested in the surveys that showed an apparent increase in populations in caves that were previously thought to have declining populations and that some new discoveries in certain caves may hint at larger populations in underground systems inaccessible to humans. Raffe Stargel