Streamside salamander
The streamside salamander is a species of mole salamander from North America, occurring in several Midwestern states of the US.
Description
The streamside salamander is a medium-sized amystomatid salamander. It typically has a relatively small head and a short rounded snout. The salamander's body is relatively short and flaccid. There are 14-15 distinct costal grooves when fully grown. The tail is fairly short and thick, and it contains costal grooves that correspond directly to the vertebrae. Coloring is typically a dark black background covered in lichen-like markings in gray and brown. The species has more teeth, with a unique cusp shape, in its maxillary and premaxillary positions than its close relatives teeth, and is somewhat stockier.Distribution and habitat
The species is found in central Kentucky, southwestern Ohio, southeastern Indiana. There is an isolated population in Livingston County, Kentucky. Overall distribution is uncertain due to the species' cryptic habits and possible confusion or hybridization with the small-mouth salamander. Adults can be found underground and under rocks or leaves in deciduous forests at moderate elevations.The streamside salamander is closely related to the pond-breeding small-mouth salamander, from which it is believed to have diverged during the late Pleistocene era as a result of climatic warming. Disappearance of pond habitats are thought to have forced the species to adapt to the new stream habitat.
Ecology
Predator avoidance
The female places eggs on the underside of submerged rocks in stream pools to reduce risk of predation on eggs by fish. The salamander also uses olfactory cues to detect the presence of fish and tends to avoid placing eggs in pools that have high fish densities. Adults are not normally at risk of fish predation, but both eggs and young larvae may be targeted. It has been shown that the hatching time of streamside salamander eggs was responsive to the presence of green sunfish in the habitat, leading to the emergence of larvae that are larger and less easily preyed on, or possibly less susceptible to involuntary drift into areas with high fish densities.Larvae show a range of coloration types that are believed to be driven by several different mechanisms. In fish-rich habitats, larvae tend to have light pigmentation that assists in blending in with the stream substrate and reduces the likelihood of being detected by predators. In the absence of predators, darker pigmentation that may assist in maintaining a higher body temperature and thus greater activity and foraging levels is more common. Risk of UV light damage may also drive a preference for darker coloration. Larvae may be able to play off these differing pigmentation drivers against each other by preferentially seeking out darker sediment that allows high camouflage while maintaining dark pigmentation.