Southern torrent salamander

Description

The southern torrent salamander (Rhyacotriton variegatus) is a member of the salamander family Rhyacotritonidae. This species of torrent salamander is found the farthest south in the region. It is a small salamander endemic to the Pacific Northwest from Northern California to Northern Oregon. It is one of four species of Rhyacotriton, along with R. cascadae, R. kezeri and R. olympicus. All species of Rhyacotriton are small, with their body lengths being less than 5 inches. The species reproduces annually, with an extended courtship and egg-laying period. The time it takes from oviposition to reach sexual maturity ranges from five to eight years, making the generation interval rather long. The larval stage, from hatching to metamorphosis, lasts 2.0-2.5 yr, with females requiring another 1.5–2.0 yr until they can first breed. They reach sexual maturity 1.0-1.5 yr after metamorphosis which occurs between 4.5 and 5.0 yr. This species feeds on small insects and spiders. Although it is found over a large area, it is not a migratory creature. It is preyed on by Pacific giant salamanders and garter snakes. The species in the genus Rhyacotriton are all similar in morphology, but have high genetic diversity. R. variegatus lives in aquatic environments from egg through metamorphic stages. Through adulthood individuals live on the waters edge 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. The habitats preferred by R. variegatus are cool, shallow, high in oxygen, and slow-flowing, such as seeps and mountain brooks, with coarse, gravel-like beds. These water sources are found mostly in forests, which is where R. variegatus is most often found. All species of Rhyacotriton have aquatic eggs and larvae, and adults are semi-aquatic. R. variegatus adults can venture away from the stream, but they prefer the water, only coming out when the moisture level of the ground is high enough. Adults and juveniles are subject to moisture loss as well as heat shock. The southern torrent salamanders are small salamanders; mature adults measure from 1.5–2.4 inches snout to vent. On their dorsal sides, they are brown with darker spots. Their ventral sides are more yellow, with the same spots as the dorsal sides. The colors vary by shades; the dorsal sides range from dark olive to a dark brown.