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Canadian Herpetological Society Société d'Herpétologie du Canada |
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Northern Two-lined Salamander
Eurycea bislineata
Family: Plethodontidae
COSEWIC status:- Not Assessed
- No Status
- Least Concern
Description
The Northern Two-lined Salamander is slender-bodied and can attain a total length of about 12 cm. Individuals are green, yellow or orange with black specks and two dark brown or black stripes that run down the back and extend onto the tail. There is often grey mottling on the sides and the belly is yellow. Northern two-lined Salamanders have 13–16 costal groves and a laterally compressed tail. Aquatic larvae have gills and a tail fin and are dark in colour with six to nine pairs of light spots on the sides.
Similar Species
The Northern Two-lined Salamander can be confused with several other species of Plethodontid salamanders. The Eastern Red-backed Salamander has a dark body with a distinct red stripe down the back and lacks the laterally compressed tail. The Northern Dusky Salamander and Alleghany Mountain Dusky Salamander both have a diagonal line running from the jaw to the eye and they lack the two dark lines running down the back.
Distribution
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In Canada, the Northern Two-lined Salamander occurs in eastern Ontario, much of Quebec, New Brunswick and Labrador. This species occurs throughout the northeastern United States south to Ohio, Virginia and West Virginia.
Habitat
The Northern Two-lined Salamander breeds in small, fast-flowing rocky woodland streams or seeps, and the larvae reside in these habitats until they mature. Outside of the breeding season, adults inhabit the stream margins as well as the forest floor within close proximity (< 100 m) of these streams. Cover objects, such as rocks and woody debris are important microhabitats that provide moist conditions and shelter. Eggs are attached to the underside of submerged rocks within the stream or along the stream banks. Individuals hibernate underground in the forest surrounding the breeding streams.
Biology
Plethodontid salamanders, including the Northern Two-lined Salamander, are also known as lungless salamanders because the adults do not have lungs or gills; instead, they absorb oxygen directly through their skin. They must remain moist at all times so that oxygen and carbon dioxide can diffuse through the skin. Northern Two-lined Salamanders primarily breed in the spring, though some fall breeding may also occur. Individuals congregate to breed in streams or seeps where the female will deposit the eggs. The female lays up to 50 (average of 25) eggs in the spring, and she guards the eggs until they hatch in late summer. The larvae undergo metamorphosis after one or two years, and individuals reach sexual maturity about two years after metamorphosis. The longevity of this species is unknown. Juvenile and adult Northern Two-lined Salamanders forage around the margins of streams and on the forest floor for insects, spiders, worms and other terrestrial invertebrates, while larvae primary eat aquatic benthic invertebrates.
Threats
The primary threat to this species is the loss of mature forest, primarily through urbanization, clearing of land for agriculture and logging. However, this species occurs throughout large, relatively undeveloped regions of the Canadian Shield, and threats to these populations are likely minimal. Pollution, such as herbicides, agricultural effluent and road salt can be detrimental to salamanders since toxins are easily absorbed though their skin. Climate change and introduced pathogens pose potentially serious future threats to Canadian salamanders.