Tennessee Cave Salamander

Adults are 100-230 mm TL and have 17-19 costal grooves (Stuart et al. 2008). Most individuals do not exceed 100 mm SVL (Dent and Kirby-Smith 1963). This species has a stout body, reduced black eyes, a broad head, and a truncated snout (Petranka 1998). Its gills are long, bright red, and tend to curl upward and forward over the head (McCrady 1954). The tail is oar-like and compressed laterally (McCrady 1954). The skin is generally translucent and sparsely pigmented, appearing pinkish to flesh-colored from underlying blood capillaries, depending on the subspecies (G. p. palleucus is pale while G. p. necturoides is dark; Lazell and Brandon 1962). There may also be tannish-gray pigmentation and spots dorsally and laterally (McCrady 1954). This species is mostly neotenic, but naturally metamorphosed individuals are occasionally found (Yeatman and Miller 1985, Sinking Cove Cave; Brandon et al. 1986, Custard Hollow Cave). It can be induced to metamorphose in a laboratory setting; Dent and Kirby-Smith (1963) reported that two untreated individuals metamorphosed completely and one metamorphosed partially, while Blair (1961) reported that one individual metamorphosed after three months of iodine-potassium iodide treatment but another did not metamorphose after six months of treatment, and Yeatman (1967) was also able to hormonally induce metamorphosis in this species. Gyrinophilus palleucus has 2 subspecies, G. p. necturoides and G. p. palleucus. Subspecies differ slightly in body pigmentation, head width, leg length, eye size, and modal number of trunk vertebrae (Brandon 1966; Brandon 1967). The Big Mouth Salamander, G. p. necturoides, differs from G. p. palleucus by having one or two additional costal grooves (usually 18 costal grooves, sometimes 19 in G. p. necturoides; usually 17 costal grooves, sometimes 18 in G. p. palleucus) and by its darker, spotted coloration. G. p. necturoides ranges in color from a russet brown to dark brown to deep purple-brown on the dorsum, with numerous blackish spots that extend from the level of the jaw down to the anterior third of the tail. A dark chevron-like pattern is sometimes present. The venter is pearl-gray, with rosy coloration at the limb insertions and the vent. Two parallel lateral rows of small white dots, corresponding to the costal spaces, run along the sides from the axilla onto the basal half of the tail. A distinct, pale cheek stripe extends from the base of the most ventral gill ramus onto the side of the head. Gills are a deep brilliant red and extend back to the fourth costal groove. Between adpressed limbs, 7-8 costal grooves are visible (Lazell and Brandon 1962). The Pale Salamander, G. p. palleucus, is the paler of the 2 subspecies and generally has fewer costal grooves (17 costal grooves, sometimes 18 in G. p. palleucus, vs. 18 costal grooves, sometimes 19 in G. p. necturoides; Lazell and Brandon 1962).The Tennessee Cave Salamander complex includes G. palleucus (with two subspecies, G. p. palleucus and G. p. necturoides) and G. gulolineatus, the Berry Cave Salamander (Miller and Niemiller 2008). Some populations in caves of the Tennessee Valley in northeastern Alabama (Blowing Cave, Jackson Co.) may be intergrades between G. p. palleucus and G. p. necturoides, based on the coloration and spotting pattern (Lazell and Brandon 1962; Brandon 1965; Brandon 1966; Brandon 1967).

It can be found on the southern Cumberland Plateau of south-central Tennessee and northeastern Alabama, in the Nashville Basin southeast of Nashville, Tennessee, northwestern Alabama and northwestern Georgia, USA (Godwin 1995). G. p. palleucus inhabits caves in the Crow Creek drainage system of the Lower Tennessee River watershed of Franklin Co., TN and Jackson Co., AL (Miller and Niemiller 2008). G. p. necturoides is known from several localities in the upper Elk River watershed, within the Big Mouth-Big Room Cave system, in the Eastern Highland Rim of Grundy Co., TN (Miller and Niemiller 2008). Adults have been found in caves with streams, rimstone pools, stream runs and pools, and pools isolated by receding water. Substrates can be rock, gravel, sand, or mud. Water is usually clear and free of sediment. Sinkholes are an important habitat component because they allow detritus inflow, which sustains large invertebrate populations (Caldwell and Copeland 1992). McCrady (1954) found individuals in Tennessee caves at altitudes 900-1200 ft above sea level.

This species is troglobitic, but sometimes individuals may be found in streams or springs outside caves, probably washed out by heavy rain (Miller and Niemiller 2008). It is generally found underneath rocks in pools. This species has not been observed moving very much and an individual may stay in the same spot for months (Simmons 1975). The breeding season is not known, but Lazell and Brandon (1962) reported that H. C. Yeatman found an adult male with a spermatophore protruding from its cloaca on August 24, 1954. Simmons (1975) suggested that females have irregular breeding patterns and may skip one or more years between breeding. He also suggested that females oviposit in autumn or early winter, based on discovery of small hatchlings on December 21 and February 15. Eggs have never been found and its nesting biology is unknown (Petranka 1998). Growth rates are probably slow and larvae may take many years to become sexually mature (Brandon 1967). All specimens of G. p. palleucus greater than 70 mm SVL are sexually mature (Petranka 1998).Stomach contents of 19 specimens from several caves included oligochaetes, amphipods, isopods, crayfish, cladocerans, beetles, stoneflies, mayflies, dipterans, caddisflies, thrips, and two conspecific salamanders (Simmons 1975). Amphipods made up 21% of the prey items (Simmons 1975). Miller and Niemiller (2008) reported that isopods were a common prey item, and that occasionally salamanders being handled would regurgitate epigean (relatively surface-dwelling) invertebrate prey such as earthworms and coleopteran larvae. Few predators have been documented. Simmons (1975) reported cannibalism. Lazell and Brandon (1962) reported that captive G. p. necturoides consumed adult Eurycea bislineata as well as earthworms and suggested that the urodele skull base and vertebrae found in the stomach of one wild-caught specimen were probably from a conspecific G. p. necturoides. Lee (1969) found a large adult in the stomach of a cave-dwelling bullfrog. Crayfish probably feed on small larvae (Petranka 1998).

Local populations are assumed to be very small since surveys rarely find more than 10-20 individuals per cave visit (Petranka 1998). However, Miller and Niemiller (2008) suggest that more animals may reside in subterranean waters that connect caves to each other and in caves inaccessible to humans. It is found in at least one protected area: Russell Cave National Monument, Tennessee (Godwin 1995). Although Beachy (2005) suggested that all populations of Tennessee Cave Salamanders were declining, based on comparisons of historic and recent survey numbers, and Caldwell and Copeland (1992) suggested that some populations, such as the population in Custard Hollow Cave, Franklin Co., TN, may be declining, Miller and Niemiller (2008) reported stable or increasing populations. Specifically, Miller and Niemiller (2008) found that Crow Creek drainage-associated caves in Franklin Co., TN (Custard Hollow Cave, Cave Cove Cave, and Sinking Hole Cave), plus Mudflats Cave, appeared to have stable, robust populations with no declines. Furthermore, the Big Mouth Cave population appeared to be increasing (Miller and Niemiller 2008). In contrast, the Central Basin, Warren Co., Marion Co., northwest Georgia, nearly all Valley and Ridge caves, and several Grundy Co. caves were found to have very low abundance of salamanders (Miller and Niemiller 2008).Agricultural and residential runoff, increased runoff and silt load due to deforestation, mining, urbanization, flooding after dam construction, and deposition of trash in sinkholes may all be contributing to declines (Petranka 1998, Stuart et al. 2008). Overcollecting may also be contributing to population decline of this species (Miller and Niemiller 2008).

Maximum longevity: 18.5 years (captivity)

The Tennessee cave salamander (Gyrinophilus palleucus) is a species of salamander in the family Plethodontidae, endemic to the Appalachian Mountains in the United States. Its natural habitats are streams in caves. It is threatened by habitat loss.