Plethodon punctatus Highton, 1972
Cow Knob Salamander, White-spotted Salamander
© 2016 Will Lattea (1 of 3)
Country distribution from AmphibiaWeb's database: United States
U.S. state distribution from AmphibiaWeb's database: Virginia, West Virginia
Plethodon punctatus Highton, "1971" 1972
Joseph C. Mitchell1
1. Historical versus Current Distribution. Cow Knob salamanders (Plethodon punctatus) are restricted to elevations > 850 m on Shenandoah Mountain, Augusta and Rockingham counties, Virginia; Pendleton County and North Mountain in Hardy County, West Virginia; and Shenandoah County, Virginia (Highton, 1972, 1988a). Recent inventories have expanded the known range to include Hampshire County, West Virginia, down to 732 m elevation (Pauley, 1998; R. Highton, personal communication).
2. Historical versus Current Abundance. Unknown historically. Cow Knob salamanders apparently are uncommon in many areas of their range but may be abundant at the surface in small pockets associated with ample rock cover and deep soils. Known density estimates range from 0.03–0.54/m2 in Rockingham County, Virginia (Fraser, 1976b), to 1.62/m2 in Pendleton County, West Virginia (Tucker, 1998).
3. Life History Features. Petranka (1998) has summarized the life history and biology of Cow Knob salamanders.
A. Breeding. Reproduction is terrestrial.
i. Breeding migrations. This species does not migrate. Spermatophores are deposited in early spring. Mating probably occurs in spring and fall. Based on the presence of enlarged follicles, Tucker (1998) thought that egg laying occurs February–April (although R. Highton [personal communication] feels this is unlikely).
ii. Breeding habitat. The breeding habitat of Cow Knob salamanders is unknown. This species may be more subterranean than other large Plethodon and may mate underground. Pairs of males and females have been found under rocks in spring and fall, suggesting that some mating occurs in the forest floor.
i. Egg deposition sites. Eggs are deposited beneath rocks or underground in deciduous forest habitats, but no nests have been reported for this species.
ii. Clutch size. From 7–16 eggs.
C. Direct Development.
i. Brood sites.
ii. Parental care. Unknown, but present in all known Plethodon in which nests have been found (R. Highton, personal communication).
D. Juvenile Habitat. Young of the year emerge on the surface in September. No special habitat characteristics are known for juveniles, and they are apparently the same as adult habitat characteristics.
E. Adult Habitat. Cow Knob salamanders have been observed in hemlock (Tsuga canadensis) stands, old-growth hardwoods, and mature hardwoods. They do not appear to be restricted to any one forest type as long as forest floor and subterranean features and canopy cover are present (Green and Pauley, 1987; Buhlmann et al., 1988; Tucker, 1998). Adults and juveniles are most commonly found under rocks in moist areas in deep soil on north-facing slopes above 914 m. This species had been found most often in mature and virgin hardwood forest patches. Individuals occasionally are found in younger hardwoods but not in pine forests, young hardwoods, or clearcuts.
F. Home Range Size. Unknown. Movements are probably only a few meters in the lifetime of an individual. Buhlmann et al. (1988) reported movements of < 2m to 17.4 m. Tucker (1998) recaptured one individual that had moved 0.9 m.
G. Territories. The territorial behavior of this species has not been studied.
H. Aestivation/Avoiding Dessication. Surface abundance of Cow Knob salamanders is influenced by environmental conditions (Buhlmann et al., 1988; Tucker, 1998). Adults and juveniles are active during cool, wet periods in the spring (April–June) and autumn (September–October). Individuals remain underground during warm, dry months.
Migrations. This species does not exhibit seasonal migrations.
K. Interspecific Associations/Exclusions. Other salamanders that occur sympatrically with Cow Knob salamanders are Jefferson salamanders (Ambystoma jeffersonianum), spotted salamanders (Ambystoma maculatum), Allegheny Mountain dusky salamanders (Desmognathus ochrophaeus), spring salamanders (Gyrinophilus porphyriticus), four-toed salamanders (Hemidactylium scutatum), eastern newt (Notophthalmus viridescens) efts, eastern red-backed salamanders (Plethodon cinereus), white-spotted slimy salamanders (Plethodon cylindraceus), Shenandoah Mountain salamanders (Plethodon virginia), and red salamanders (Pseudotriton ruber; Mitchell et al., 1999). Fraser (1976a,b) determined that there was little competition between juvenile and adult Cow Knob salamanders and adult Shenandoah Mountain salamanders (then recognized as Valley and Ridge salamanders; Plethodon hoffmani) for food and habitat characteristics. White-spotted slimy salamanders have been found syntopically with Cow Knob salamanders (Pauley, 1995b, 1998; Mitchell, 1996; Tucker, 1998), but interactions with this larger Plethodon have not been studied.
L. Age/Size at Reproductive Maturity. Sexual maturity is reached in about 3 yr after hatching (Fraser, 1976a), when males are approximately 49 mm SVL and females are 59 mm SVL (Tucker, 1998).
M. Longevity. Length of life is unknown but is probably similar to that of other large Plethodon—about 15 yr (Snider and Bowler, 1992).
N. Feeding Behavior. Cow Knob salamanders are opportunistic carnivores on and above the forest floor during wet conditions. Most active foraging apparently occurs at night. Individuals have been observed to climb on tree trunks and rocks at night (Buhlmann et al., 1988). It is unknown whether foraging takes place under leaf litter or underground during dry periods, but it is likely that most energy consumption occurs during wet weather, as in other terrestrial salamanders.
Adults and juveniles prey on a wide variety of invertebrates, including ants, collembolans, beetles, dipterans, coleopterans, orthopterans, insect larvae, millipedes, centipedes, spiders, and mites (Fraser, 1976b; Tucker, 1998). The size of the prey item is positively correlated with the size of the salamander.
O. Predators. Not reported, but Petranka (1998) suggested shrews, small birds, woodland snakes, opossums, and skunks.
P. Anti-Predator Mechanisms. Mechanisms to fend off predators are unknown, but mucous secretions in the tail may inhibit swallowing by small predators such as snakes (e.g., Diadophis sp. and Lampropeltis sp.) and shrews.
Q. Diseases. No diseases have been reported in this species.
R. Parasites. Cepedietta michiganensis (a protozoan) and Batracholandros magnavilvaris (a nematode) are known to occur in the digestive tract (Tucker, 1998), but the etiology of these parasites is unknown.
4. Conservation. The George Washington National Forest, in which most of the range of Cow Knob salamanders occurs, recognizes this as a Sensitive species. Most of the land > 914 m has been allocated to Management Area 4 (areas off limits to logging) and has been designated as the Shenandoah Mountain Crest Special Biological Area. A formal Conservation Agreement exists, via a Memorandum of Understanding between the George Washington National Forest and the U.S. Fish and Wildlife Service, that affords the habitat of this species on public lands some protection from logging and other potentially damaging operations (Mitchell, 1994b). Cow Knob salamanders are listed as a Species At Risk by the U.S. Fish and Wildlife Service and a Species of Special Concern in Virginia and West Virginia (Mitchell et al., 1999). Cow Knob salamanders may be threatened by logging operations and the loss of hemlock trees by the introduced hemlock woolly adelgid (Adelges tsugae), and potentially threatened by defoliation of canopy hardwood trees by the introduced gypsy moth (Lymantria dispar).
1Joseph C. Mitchell
2Thomas K. Pauley
Literature references for Amphibian Declines: The Conservation Status of United States Species, edited by Michael Lannoo, are here.
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Citation: AmphibiaWeb. 2023. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 29 May 2023.
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