The red-backed (or redback) salamander (Plethodon cinereus) is a species of small, hardy woodland salamander in the family Plethodontidae. The species inhabits wooded slopes in eastern North America, west to Missouri, south to North Carolina, and north from southern Quebec and the Maritime Provinces in Canada to Minnesota. It is also known as the eastern red-backed salamander or the northern red-backed salamander to distinguish it from the southern red-backed salamander (Plethodon serratus). It is one of 55 species in the genus Plethodon.
Description and ecology
The red-backed salamander is a small terrestrial salamander, 5.7–10.0 cm (2.2–3.9 in) in total length (including tail), which usually lives in forested areas under rocks, logs, bark, and other debris. It is one of the most numerous salamanders throughout its range. The red-backed salamander exhibits color polymorphism and two color variations are common: the 'red-backed' or 'red-stripe' variety has a red dorsal stripe that tapers towards the tail, and the darker variety, known as the 'lead-backed' (or simply 'lead') phase, lacks most or all of the red pigmentation. The red-backed phase is not always red, but may actually be various other colors (e.g., yellow-backed, orange-backed, white-backed, or a rare erythristic morph in which the body is completely red). Both morphs have speckled black and white bellies.
The skin of red-backed salamanders was found to contain Lysobacter gummosus, an epibiotic bacterium which produces the chemical 2,4-diacetylphloroglucinol and inhibits the growth of certain pathogenic fungi.
Antipredator behavior of P. cinereus was found to differ between the two color phases; the lead-backed phase has a tendency to run far away from predators, whereas the red-backed phase often stays immobile and possibly exhibits aposematic coloration. Stress levels of each color phase were estimated by determining the ratio of neutrophil to lymphocyte cells in the blood, and the results suggest stress levels are higher in the lead-backed phase than in the red-backed phase. This may be a consequence of a higher predation risk experienced in the wild by the lead-backed phase, and may also mean lead-phase salamanders could be more vulnerable in captivity settings.
Reproduction and biomass
Males and females of P. cinereus typically establish separate feeding and/or mating territories underneath rocks and logs. However, some red-backed salamanders are thought to engage in social monogamy, and may maintain codefended territories throughout their active periods. Breeding occurs in June and July. Females produce from four to 17 eggs in a year. The eggs hatch in 6–8 weeks. Not much is known about the dispersal of neonates, although neonates and juveniles are thought to be philopatric. The species largely consumes invertebrates and other detritus dwellers. In some areas with good habitat, these salamanders are so numerous, their population densities may surpass 1,000 individuals per acre (2,471 individuals per hectare). Pokagon State Park in Indiana is one such place.
- IUCN SSC Amphibian Specialist Group (2014). "Plethodon cinereus". IUCN Red List of Threatened Species. Version 2014.3. International Union for Conservation of Nature. Retrieved 2015-01-16.
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- Integrated Taxonomic Information System [Internet] 2012. [updated 2012 Sept; cited 2012 Nov 26] Available from: www.itis.gov
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- Brucker, Robert M.; Baylor, Cambria M.; Walters, Robert L.; Lauer, Antje; Harris, Reid N.; Minbiole, Kevin P. C. (2008). "The Identification of 2,4-diacetylphloroglucinol as an Antifungal Metabolite Produced by Cutaneous Bacteria of the Salamander Plethodon cinereus". Journal of Chemical Ecology. 34 (1): 39–43. doi:10.1007/s10886-007-9352-8. PMID 18058176.
- Venesky, Matthew D.; Anthony, Carl D. (2007). "Antipredator adaptations and predator avoidance by two color morphs of the eastern red-backed salamander, Plethodon cinereus". Herpetologica. 63 (4): 450–458. doi:10.1655/0018-0831(2007)63[450:AAAPAB]2.0.CO;2.
- Davis AK, Milanovich JR (2010). "Lead-phase and red-stripe color morphs of red-backed salamanders Plethodon cinereus differ in hematological stress indices: A consequence of differential predation pressure?" Current Zoology 56 (2): 238–243.
- APPALACHIAN NATURE: An Entrée of Salamanders
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- Green R (1818). "Descriptions of several species of North American Amphibia, accompanied with observations". Journal of the Academy of Natural Sciences of Philadelphia 1 (2): 348-359. (Salamandra cinerea, new species, pp. 356-357). (in English and Latin).
- Powell R, Conant R, Collins JT (2016). Peterson Field Guide to Reptiles and Amphibians of Eastern North America, Fourth Edition. Boston and New York: Houghton Mifflin Harcourt. 494 pp., 47 color plates, 207 Figures. ISBN 978-0-544-12997-9. (Plethodon cinereus, pp. 78-80 + Plate 5 + Figures 33, 36, 37).
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Data related to Plethodon cinereus at Wikispecies