A small to medium-sized, semi-aquatic salamander. Dorsal coloration is brown and the underside is bright yellow. Black flecks or spots occur on the back and more densely on the sides. The degree of black spotting or blotching varies with locality, but there seems to be no geographic pattern. The belly sometimes has small grayish flecks. Some populations have a dark stripe on the underside of the tail, posterior to the vent opening. Males have squared, glandular lobes on either side of the vent opening, a trait unique among salamanders (Sever 1988). These salamanders have a short, rounded snout and relatively large, prominent eyes. The tail is relatively short, less than the snout to vent length. Description from Good and Wake (1992),Leonard et al. (1993), and Petranka (1998). Adult body size is 4.0 to 5.1 cm snout to vent length (7.5 - 11 cm total length) (Good and Wake 1992; Petranka 1998). Females are slightly larger than males (Good and Wake 1992).Larvae are of the stream type, with very short gills and a low dorsal tail fin that does not extend onto the back. Coloration is similar to the adult pattern (Stebbins 1985; Leonard et al. 1993).Hatchling size is about 15.8 mm snout to vent length (Nussbaum and Tait 1977).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: United States
U.S. state distribution from AmphibiaWeb's database: Oregon, Washington
The distribution of R. cascadae is restricted to the western slope of the Cascades Mountains from just north of Mt. St. Helens, Skamania Co., Washington, to northeastern Lane Co., Oregon (Good and Wake 1992). Torrent salamanders inhabit forested areas with high humidity and dense canopy cover (Good and Wake 1992; Nussbaum et al. 1993).Individuals are found near seepages and small, rocky streams, preferring to occupy the splash zone (Nussbaum and Tait 1977; Petranka 1998). Larvae are usually found in loose gravel.Adults are rarely found more than a meter from the streams edge (Good and Wake 1992).
Life History, Abundance, Activity, and Special Behaviors
Courtship has not been observed for any species of Rhyacotriton (Petranka 1998). Courtship and mating occur over most of the year, concentrated in the fall and spring months, based on the presence of spermatophores in the cloacae of females. Females may oviposit at any time of the year, but tend to lay in late spring (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. cascadae (Nussbaum 1969). Number of mature ovarian eggs (correlated with clutch size) ranges from 2-13 (Nussbaum and Tait 1977), and average clutch size is 8 (Nussbaum and Tait 1977; Good and Wake 1992). In a nest of the closely related species R. kezeri, at least three females may have laid their eggs communally (Nussbaum 1969).There is apparently no attendance of the developing eggs (Nussbaum 1969; Nussbaum and Tait 1977). Clutch frequency is once per year (Nussbaum and Tait 1977; Nussbaum et al. 1983). Eggs laid in spring hatch 5-6 months later (Nussbaum 1969).
Information on diet of R. cascadae is not available, but adults and juveniles likely feed on a mixture of aquatic and semiaquatic invertebrates. Likewise, natural predators have not been documented but larval and adult Pacific giant salamanders (Dicamptodon), as well as garter snakes (Thamnophis) are probably important. See Petranka (1998) and references therein. Rhyacotriton respond to attacks by coiling the body and raising and undulating the tail which contains poison glands (Nussbaum et al. 1983).
Larvae may be abundant and densities have been estimated at 28 - 41 individuals/m2 (Nussbaum and Tait 1977).
Trends and Threats
Logging of old-growth forests is the main threat to populations of R. cascadae. Larvae are likely affected by increased siltation following logging, and adults are sensitive to environmental temperature and moisture levels. Logging also eliminates suitable habitat (Bury 1983; Good and Wake 1992; Petranka 1998; Welsh and Lind 1991).
Until recently the genus Rhyacotriton contained a single species with two subspecies, R. o. olympicus and R. o. variegatus. Genetic studies revealed substantial variation and subdivision throughout the range and the single species was split into four species: R. olympicus, R. variegatus, R. cascadae, and R. kezeri (Good et al. 1987; Good and Wake 1992).
Bury, R. B. (1983). "Differences in amphibian populations in logged and old growth redwood forest." Northwest Science, 57, 167-178.
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.
Leonard, W.P., Brown, H.A., Jones, L.L.C., McAllister, K.R., and Storm, R.M. (1993). Amphibians of Washington and Oregon. Seattle Audubon, Seattle.
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.
Petranka, J. W. (1998). Salamanders of the United States and Canada. Smithsonian Institution Press, Washington D.C. and London.
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.
Welsh, H. H., Jr. and Lind, A. J. (1991). ''The structure of the herpetofaunal assemblage in the Douglas-fir/hardwood forests of northwestern California and southwestern Oregon.'' Wildlife and Vegetation of Unmanaged Douglas-fir Forests, USDA Forest Service, General Technical Report PNW-GTR-285. L. F. Ruggiero, K. B. Aubry, A. B. Carey, and M. H. Huff, eds., USDA Forest Service, 394-413.
Originally submitted by: Meredith J. Mahoney (first posted 2000-07-19)
Edited by: M. J. Mahoney (2001-06-04)
Species Account Citation: AmphibiaWeb 2001 Rhyacotriton cascadae: Cascade torrent salamander <https://amphibiaweb.org/species/4232> University of California, Berkeley, CA, USA. Accessed Jun 18, 2021.
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Citation: AmphibiaWeb. 2021. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 18 Jun 2021.
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