Description
Rhyacotriton olympicus has a snout-vent length between 4.1 and 6.2 cm (Stebbins 1985) and tends to be the largest species of Rhyacotriton (Good and Wake 1992). Gaige (1917) originally described R. olympicus with "skin shining, closely pitted, without tubercles". The salamander has 14 costal grooves, one median dorsal groove, and five toes on short, well-developed limbs which fail to meet when adpressed. Toes are distinct and rounded, the third toe being longest, with the second and fourth and first and fifth being equal in length. The snout is rounded, head small and depressed, with nostrils near the end of the snout. The eyes are prominent, and eyelids appear swollen. The tail is shorter than snout-vent length, with strong lateralcompression and keeled above, ending in an obtuse point. The vent is a longitudinal slit with a distinct transverse groove at the posterior end (Gaige 1917). Males have distinct squarish, glandular vent lobes, a trait unique among salamanders (Stebbins 1985; Sever 1988). Stebbins and Lowe (1951) and Good and Wake (1992) described adult coloration as uniformly dark chocolate brown above with the dark dorsal coloration ending distinctly along the side in a wavy line. Ventrally, the salamander is orange yellow with mottling of brownish in the gular area, and with well defined dark spots on the underside of the body and tail.

Stebbins and Lowe (1951) described the aquatic larvae as similar to adults in coloration, but with a more mottled appearance. Very young larvae may have whitish venters, but larger larvae are more similar to adult in ventral coloration. They have short gills and adult proportions and are of the stream larva type(Stebbins 1985).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: United States

U.S. state distribution from AmphibiaWeb's database: Washington

View distribution map in BerkeleyMapper.

Rhyacotriton olympicus is restricted to the Pacific Northwest of the United States, specifically the Olympic Peninsula in Callam, Grays Harbor, Jefferson, and Mason counties Washington (Good and Wake 1992). The preferred habitat is along the water-washed or moss-covered edges of well-shaded, fast-flowing permanent streams (Good and Wake 1992; Stebbins and Lowe 1951), although the preferred resting habitat tends to be relatively slow-moving waters(Stebbins and Lowe 1951). There is usually a good leaf canopy, with the streamside being characterized by abundant vegetation, moss and a thick leaf mat (Stebbins and Lowe 1951). The salamanders tend to be active at cold water temperatures ranging between 5 and 10 degrees Celsius. Larvae are most common in gravel through which water is percolating, and adults prefer the splash zones of waterfalls, under large loose sheets of rock on faces where a thin layer of water is running (Good and Wake 1992). Rhyacotriton olympicus are associated with old growth forest, with Douglas fir, tanbark oak, bay, madrone, alder, and maple as common species (Good and Wake 1992; Stebbins and Lowe 1951). Adults can be found away from stream or spring habitat, mostly after heavy rains (Nussbaum et al. 1983).

Life History, Abundance, Activity, and Special Behaviors
Most breeding of R. olympicus occurs in spring and early summer. The sexually active male may perform a tail-wagging display towards the female prior to spermatophore deposition, curling the tail and arching the back (Arnold 1977). Females laying single, unpigmented eggs in clusters of 2-16 (Stebbins and Lowe 1951; Stebbins 1985), but larger clusters may be found due to communal egg laying (Nussbaum 1969; Stebbins 1985). There is apparently no attendance of the developing eggs (Nussbaum 1969; Nussbaum and Tait 1977). In other species of Rhyacotriton, egg deposition sites are in seeps at the heads of springs and this is likely to be similar in R. olympicus (Nussbaum 1969). Clutch frequency is once per year (Nussbaum et al. 1983). Research on other species of Rhyacotriton indicates that females may lay at any time of the year, but tend to lay in late spring (Nussbaum and Tait 1977). Larvae may take over three years to metamorphose, and metamorphosis usually occurs between 30 and 40cm SVL (Stebbins 1985; Nussbaum et al. 1983).

The larval diet may include a variety of aquatic invertebrates, an varies with availability and location (Nussbaum et al. 1983). The diet of metamorphosed Rhyacotriton includes aquatic and semi-aquatic invertebrates, as well as larval and adult beetles, flies, earthworms, snails and other invertebrates (Nussbaum et al. 1983).

Predators of Rhyacotriton probably include the giant salamander, Dicamptodon, and garter snakes, but have not been reported (Nussbaum et al. 1983). Large larvae and adults may exhibit a defensive behavior consisting of coiling the body and elevating and undulating the tail, exposing the bright yellow underside (Nussbaum et al. 1983).

Trends and Threats
Although Rhyacotriton is abundant in its habitat, it is associated with old-growth forest, and is virtually absent from recently logged areas, most likely due to decreased temperatures, increased humidity, and susceptibility to desiccation (Good and Wake 1992; Stebbins and Lowe 1952).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities

Comments
Rhyacotriton was first described by Gaige (1917) as a member of the hynobiid genus Ranodon. Dunn (1920) placed it in the family Ambystomatidae and it was subsequently placed in its own subfamily, Rhyacitritoninae by Tihen (1958). Regal (1966) placed Rhyacotriton in the subfamily Dicamptodontinae, which was elevated to the family Dicamptodontidae by Edwards (1976). The genus was finally placed in its own family by Good and Wake (1992). Considered to contain only one species, R. olympicus, until the work of Good et al. (1987), thefamily now contains four species , R. olympicus, R. variegatus, R. kezeri, and R. cascadae(Good and Wake 1992).

References

Arnold, S.J. (1977). ''The evolution of courtship behavior in New World salamanders with some comments on Old World salamanders.'' The Reproductive Biology of Amphibians. D.H.Taylor and S.I. Guttman, eds., Plenum Press, New York, 141-183.

Dunn, E.R. (1920). ''Notes on two Pacific Coast Ambystomidae.'' Proceedings of the New England Zoological Club, 7, 55-59.

Edwards, J.L. (1976). "Spinal nerves and their bearing on salamander phylogeny." Journal of Morphology, 148, 305-328.

Gaige, H.T. (1917). "Description of a new salamander species from Washington." Occasional Papers of the Museum of Zoology, University of Michigan, (40), 1-3.

Good, D. A., Wake, D. B., and Wurst, G. Z. (1987). ''Patterns of geographic variation in allozymes of the Olympic salamander Rhyacotriton olympicus (Caudata: Dicamptodontidae).'' Fieldiana, Zoology, 32, 1-15.

Good, D. A., and Wake, D. B. (1992). ''Geographic variation and speciation in the torrent salamanders of the genus Rhyacotriton (Caudata: Rhyacotritonidae).'' University of California Publications in Zoology, 126, 1-91.

Nussbaum, R. (1969). ''A nest site of the Olympic Salamander, Rhyacotriton olympicus (Gaige).'' Herpetologica, 25, 277-278.

Nussbaum, R. A., Brodie, E. D., Jr., and Storm, R. M. (1983). Amphibians and Reptiles of the Pacific Northwest. University of Idaho Press, Moscow, Idaho.

Nussbaum, R., and Tait, C. K. (1977). ''Aspects of the life history and ecology of the Olympic Salamander, Rhyacotriton olympicus.'' American Midland Naturalist, 98, 176-199.

Regal, P.J. (1966). "Feeding specializations and the classification of terrestrial salamanders." Evolution, 20, 392-407.

Sever, D M. (1988). "Male Rhyacotriton olympicus (Dicamptodontidae: Urodela) has a unique cloacal vent gland." Herpetologica, 44, 274-280.

Stebbins, R. C. (1985). A Field Guide to Western Reptiles and Amphibians. Houghton Mifflin, Boston.

Stebbins, R.C., and Lowe, C.H., Jr. (1951). ''Subspecific differentiation in the Olympic salamander Rhyacotriton olympicus.'' University of California Publications Zoology, 50, 465-484.

Tihen, J.A. (1958). ''Comments of the osteology and phylogeny of ambystomatid salamanders.'' Bulletin of the Florida State Museum, 3, 1-50.

Species Account Citation: AmphibiaWeb 2001 Rhyacotriton olympicus: Olympic Torrent Salamander <https://amphibiaweb.org/species/4234> University of California, Berkeley, CA, USA. Accessed Nov 22, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 22 Nov 2024.

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