| Southern Torrent Salamander | |
|---|---|
| Conservation status | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Amphibia |
| Order: | Caudata |
| Family: | Rhyacotritonidae |
| Genus: | Rhyacotriton |
| Species: | R. variegatus |
| Binomial name | |
| Rhyacotriton variegatus Stebbins & Lowe, 1951 |
|
The Southern Torrent Salamander (Rhyacotriton variegatus) is a member of the Rhyacotriton family of salamanders. R. variegatus has the common name Southern Torrent Salamander for it is the species of Torrent Salamander found the furthest south in the region. It is a small salamander endemic to the Pacific Northwest from Northern California to Northern Oregon. They are one of four species of Rhyacotriton, along with R. cascadae, R. kezeri and R. olympicus. All species of Rhyacotriton are small with their body length being less than 5 inches. The species reproduces annually, with an extended courtship and egg-laying period[1] The time it takes from oviposition to reach sexual maturity ranges from 5–8 years, making the generation interval rather long.[1] The larval stage, from hatching to metamorphosis, lasts 2-2.5 years, with females requiring another 1.5–2 years until they can first breed.[1] They reach sexual maturity 1-1.5 years after metamorphosis which occurs between 4.5–5 years. This species feeds on small insects and spiders. Although they are found over a large area, they are not migratory creatures. They are predated by Pacific giant salamanders as well as garter snakes.
Contents |
The species in the Rhyacotriton family are all similar in morphology, but slight differences in genetics, location and life processes distinguish one from another. R. variegatus lives in aquatic environments from egg through metamorphic stages. Through adulthood individuals live close to sources of water, mostly along the banks among pebbles and rocks. R. variegatus has the lowest desiccation tolerance of all North American salamanders, meaning they cannot easily withstand “extreme” temperatures and low moisture levels.[2] The habitats preferred by R. variegatus are cool, shallow, high in oxygen and slow-flowing, such as seeps and mountain brooks, with a coarse gravel-like bed. These water sources are found mostly in forests, which is where R. variegatus is most often found.[2] The other species of the Rhyacotriton family also have aquatic eggs and larvae, but their adults are mostly found on land and under rocks. R. variegatus adults are not strictly aquatic, but they prefer the water, only coming out when the moisture level of the ground is high enough.[2] Adults and juveniles are subjective to moisture loss as well as heat shock.[3]
The Southern Torrent Salamanders are small salamanders found in the Rhyacotritonidae family, in the Rhyacotriton genus. Mature adults measure from 1.5-2.4 inches snout to vent. On their dorsal side, they are brown with darker spots. Their ventral side is more yellow, with the same spots as the dorsal side. The colors vary by shades, but also the dorsal side ranges from a dark olive to a dark brown. The eyes of R. variegatus face forwards and are large and dark. Metallic flecks surround the eyes as well. Males distinguish themselves from the females by square cloacal lobes. Lungs of the adults are also reduced in appearance. Their bodies are slender with a long tail which is approximately the same length as their torso. They have four legs, set in pairs – two close to the head, and two near the base of the tail. At the base of the leg, they have four toes used to grip and climb. Generally they have a blunt nose paired with protruding eyes.
The Rhyacotriton family is found in the Pacific Northwest, extending from Northern California to the Washington Peninsula. R. variegatus is endemic to the southernmost part of the range, extending from California to Oregon. Populations of R. variegatus are found in forests of the coastal regions of the states. There are some Rhyacotriton that are found more inland, but they are still relatively close to the coast; these are mainly populations of the R. kezeri species. The areas that have populations of R. variegatus are going to be forests with fresh water sources that meet all of the requirements for habitation. Although most of the population is in one continuous range, there is a smaller population separated from the main range in Southwest Oregon. Even though it is disconnected from the range, it is still close in relation to the coastline.
R. variegatus occurs in coastal coniferous forests in California and Oregon. Older forests are more likely to maintain a population of Southern Torrent Salamanders. These forests have >80% canopy coverage due to sizeable trees as well as large amounts of moss.[4] Some younger forests have the proper habitat to keep a population, but it is unusual to see a population living in a young forest. Reproduction occurs in the water, where the fertilized eggs are laid and abandoned.[1] The mating occurs after an extended courtship, and is followed by a long egg laying process. The eggs take quite some time to hatch, and the whole larval stage lasts about 2-2.5 years.[1] Usually the female lays one egg at a time, but occasionally clutches of 8-11 eggs are found.[5]
Efforts have been made to try to conserve this species. After the species was assessed, it was placed in the “Least Concern” category meaning there is no immediate threat to the survival of the species. It was listed as least concern for it has a wide distribution with an assumed large population.[4] Even though there is no immediate threat to the Southern Torrent Salamander, urbanization is beginning to encroach on the species habitat. Direct effects from logging and disturbing forests with the building of roads and other man-made features are limiting the habitable areas for these salamanders.[4] Other indirect effects from urbanization are those that affecting temperature of the environment. R. variegatus is extremely sensitive to temperature fluctuations, having a very narrow range of temperatures in which it can thrive.[2] The salamanders will begin to show temperature stress at about 63 degrees Fahrenheit. If the temperature of mountain streams and brooks rises over the next few years, the species will either have to adapt or succumb to the warm temperature. In the state of California, R. variegatus is a Species of Special Concern.[1] The composition of the ground in the habitat is also quite important. If the texture of the components is too fine, then the environment would not be ideal. R. variegatus needs large, pebble-like particles to be able to hide and avoid predators. Many still petition to place R. variegatus in a more at-risk category because of the previously unregulated logging that altered the population.[4] The species will remain at least concern status until the populations become more threatened.
Media related to [//commons.wikimedia.org/wiki/Category:Rhyacotriton_variegatus Rhyacotriton variegatus] at Wikimedia Commons Data related to Rhyacotriton variegatus at Wikispecies