Rhyacotritonidae

The family Rhyacotritonidae is formed by a single genus (Rhyacotriton). This genus was once formed by a single specie under the family Ambystomatidae, but it has since be separated into his own family and divided into 4 different species.

The Rhyacotriton are a genus of brook-dwelling salamanders distributed in the north-west coast of the United States, from northern California to Washington, with the Cascade mountains as main distribution area.

The main distinctive feature of the Rhyacotriton are unique squared-off glands behind the vent in adult males, which are not present in any other genus. They also have some other particular characteristics, such as the absence of an operculum and opercularis muscle (trait that they share with some species of Hynobiidae), and reduced lungs (such as in Plethodontidae and some Hynobiidae).

Rhyacotriton, or Torrent Salamanders, have a maximum snout to vent size of 6cm, and are adapted to life in very cold, fast moving waters, making them very susceptible to heat, with temperatures above 28°C being fatal. These salamanders are also closely tied to old-growth forest and are very susceptible to logging, making them a useful biological indicator of the recovery of degraded forests.

Males of these genus are extremely aggressive towards other males, chasing and biting intruders, especially during courtship with a female. Similarly to other salamanders, courtship behaviour involves a unique tail-wagging display, before the deposition of a spermatophore. Eggs are laid singly in water beneath stones with no parental care displayed by the adults. Larval development is slow, taking three to five years, due to the low temperature of the water (5-12° C).