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Rhyacotriton variegatusSouthern Torrent Salamander

By Haley Burger

Geographic Range

The southern torrent salamander (Rhyacotriton variegatus) can be located along the coastal western United States from northern California to sections of Oregon. These sections include the area north of Santa Rosa, California to just south of Portland, Oregon. There have been some sightings of the southern torrent salamander as far east as Klamath County, Oregon, near Crater Lake. Some isolated populations exist near Steamboat, Douglas County, Oregon on the Cascade Mountains on the western slope. There are scattered populations in low-order tributaries and headwaters. (Hammerson, 2004)

Habitat

The southern torrent salamander mainly inhabits small, clear, freshwater streams that range in temperature from 5.8 degrees Celsius to 13 degrees Celsius with a pH of around 7.6. These streams can be found throughout the mountains and forested regions of the Pacific Northwest. Low sedimentation is also a necessity because if the water is murky or unclear then it is hard for the salamander to obtain sufficient oxygen while in the water. Larvae and adults are often found under stones in shallow areas, about 15 cm deep, but may go deeper if pursued. Outside of streams, the southern torrent salamander has been found in substrates under dense canopy coverage. The average elevation at which this species can be found is 1,449 m, and the range is unreported. (Benke and Cushing, 2005; Diller and Wallace, 1996; Hammerson, 2004; Hartwell, et al., 1996; Tait and Diller, 2006)

  • Aquatic Biomes
  • rivers and streams
  • Average elevation
    1449 m
    4753.94 ft
  • Average depth
    0.15 m
    0.49 ft

Physical Description

The dorsal region of this salamander varies from brown to greenish-brown, with a bright yellow underbelly. Some black speckling on both the dorsal and ventral portions have been recorded. A short, rounded snout and large protruding eyes dominant the head. The average adult snout-vent length (SVL) is 4.1 to 6.2 cm; the average total length is 7.5 to 11.5 cm. Females’ abdomens are slightly larger than males. The female’s tail is comparatively shorter than the male’s. Males have a square cloaca.

Larvae have gills and a tail. This tail portion includes a low dorsal fin. The body color is similar to the adults, but less distinctly bicolored. They lack the bright yellow underbellies of adults, but do have the brown bicolored dorsal regions with slight speckling. The average size for hatched larvae is 13.5 mm SVL. (Good and Wake, 1992; Leonard, et al., 1993)

  • Sexual Dimorphism
  • sexes alike
  • female larger
  • Range length
    4.1 to 6.2 cm
    1.61 to 2.44 in

Development

Southern torrent salamander eggs hatch from the middle of May to early June. It takes approximately five to six months for these eggs to hatch. The metamorphosis for this species occurs in the water. The forelimbs of the embryo develop after 110 days. Hindlimbs are evident around 120 days. External gills begin to become visible at approximately 132 days. Their length is between 30.2-39.0 mm once they have hatched. Birth weight was not recorded. (Lannoo, 2005; Nussbaum, 1969)

Reproduction

Mating rituals and social hierarchy have not been observed for the southern torrent salamander. However, females do possess a courtship pheromone gland to help attract males in the mating process. It is suggested that the southern torrent salamander is polygynandrous because the females store sperm from multiple males and males breed with more than just one female. (Palmer, et al., 2005; Stebbins and Cohen, 1997)

Oviposition can occur at any time, although there is a peak of courtship and egg-laying activity in late spring to early summer months. Males seem to have more sperm in the vasa deferentia from February to April. However, because there is evidence of sperm in the vasa deferentia year-round it can be concluded that this salamander could engage in mating activity throughout the year. The largest ovarian follicles (2.0-3.9 mm) mainly occur in females from February to June. Females possess spermathecae, simple tubuloalveolar glands that have many branches from the roof of the anterior portion of the cloaca. Fertilization is internal via a spermatophore, or sperm packet.

Clutch size is around 10 to 12 eggs with 9 to 10 survivors at hatching. Once they hatch and are mobile, they are more susceptible to predators.

Eggs hatch from the middle of May to early June. It takes about 5 to 6 months for these eggs to hatch. Once hatched, it takes approximately 2-3 years to reach sexual maturity, and 4.5-5 years until they stop growing. (Karraker, 1999; Nussbaum, et al., 1983; Sever, et al., 2004)

  • Breeding interval
    Southern torrent salamanders breed once yearly
  • Breeding season
    Novemeber to December
  • Range number of offspring
    10 to 12
  • Range time to hatching
    5 to 6 months
  • Average time to independence
    0 minutes
  • Range age at sexual or reproductive maturity (female)
    2 to 3 years
  • Range age at sexual or reproductive maturity (male)
    2 to 3 years

It is unclear if parental care takes place in the southern torrent salamander. Karraker et al. (2004) concluded that parental care is highly unlikely due to the long embryonic period and because this species cannot defend the nests or eggs from larger predators. (Karraker, 1999; Karraker, et al., 2004)

  • Parental Investment
  • no parental involvement

Lifespan/Longevity

Based on other Rhyacotriton species, the southern torrent salamander is expected to have a moderately long lifespan, though less than 10 years. This prediction is based on how long it takes the species to become fully developed, which is 4 to 5 years. This does not take into consideration threats of predation and disease. There have been no reports of this salamander being held in captivity. (Lannoo, 2005)

Behavior

Both the larvae and adults burrow into the streambeds in response to lower stream flows and warmer water temperatures that are associated with summer months, and in response to colder weather associated with winter months. Howell and Maggiulli (2011) recorded that weight gain was more common during the winter months than the summer months, which suggests a period of inactivity for both the adults and larvae during the hotter, drier season of summer. In response to predatory attacks, Rhyacotriton individuals respond by curling up their bodies and raising and undulating their tails, which contain poison glands. ("Conservation assessment for the cascade torrent salamander (Rhyacotriton cascadae)", 2011; Nussbaum, et al., 1983; Stebbins and Cohen, 1997)

Home Range

No studies have indicated that this salamander species defends its territory. Hartwell et al. (1996) could not determine the home range for this salamander. (Hartwell, et al., 1996)

Communication and Perception

The southern torrent salamander uses chemical signals during the breeding season, in the form of pheromones. Males produce a pheromone that increases female receptivity to breeding.

In perceiving their surroundings, other members of the genus are known to use olfactory receptors, and their vision is described as trichromatic. It is presumed that the southern torrent salamander follows a similar pattern. (Hartwell, et al., 1996; Palmer, et al., 2005; Stebbins and Cohen, 1997)

Food Habits

The adult southern torrent salamander feeds primarily on amphipods (crustaceans) and springtails (Order Collembola). Salamanders feed upon both amphipods and springtails in the nymph and larval life stages.

The larva of this salamander species feed on the same species as the adults as well as spiders. This diet stays consistent throughout the year. (Lannoo, 2005; Rundio and Olson, 2001)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods

Predation

Pacific giant salamanders (Dicamptodontidae), garter snakes (Thamnophis), and salmonid fishes (Salmonidae), are the primary examples of predators that feed upon the southern torrent salamander. This salamander confines itself to shallow water that runs through rocks in response to the presence to the pacific giant salamander. (Bridges, 1999; Lannoo, 2005)

  • Known Predators
    • Pacific giant salamanders (Dicamptodontidae)
    • garter snakes (Thamnophis)
    • salmonid fishes (Salmonidae)

Ecosystem Roles

The southern torrent salamander is a food source for the pacific giant salamanders (Dicamptodontidae), garter snakes (Thamnophis), and salmonid fishes (Salmonidae).

No parasites have been reported for the southern torrent salamander, but several digenean flukes (flatworms) and one nematode have been collected in other species of Rhyacotrition. (Bridges, 1999; Lannoo, 2005)

Economic Importance for Humans: Positive

There are no known positive economic impacts of southern torrent salamanders on humans.

Economic Importance for Humans: Negative

There are no known negative economic impacts of southern torrent salamanders on humans.

Conservation Status

The IUCN Red List of Threatened Species has the southern torrent salamander listed as a species of “Least Concern.” The U.S. Federal rankings and CITES lists do not show any information regarding this species’ conservation status.

Timber harvesting potentially harms the southern torrent salamander because it destroys potential habitat, and increases soil temperature and sedimentation. Timber harvesting affects this species more than any other amphibian species in Oregon. Fifty to ninety percent of the suitable habitat in California has been destroyed by overharvesting old-growth forests and destruction or eradication of seeps and streams. Larvae are more vulnerable to increased siltation and the adults are more vulnerable to changes in moisture levels.

The California Department of Fish and Game Commission did not to list the species, but instead addressed problems in its Forest Practices Act that greatly impacts torrent salamanders. These issues remain unresolved today which prevents protective measures for these torrent salamanders. (; Corn and Bury, 1989; Lannoo, 2005)

Contributors

Haley Burger (author), Radford University, Cari Mcgregor (editor), Radford University, Zeb Pike (editor), Radford University, Karen Powers (editor), Radford University, April Tingle (editor), Radford University, Jacob Vaught (editor), Radford University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

diurnal
  1. active during the day, 2. lasting for one day.
ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

freshwater

mainly lives in water that is not salty.

insectivore

An animal that eats mainly insects or spiders.

internal fertilization

fertilization takes place within the female's body

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

sperm-storing

mature spermatozoa are stored by females following copulation. Male sperm storage also occurs, as sperm are retained in the male epididymes (in mammals) for a period that can, in some cases, extend over several weeks or more, but here we use the term to refer only to sperm storage by females.

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

visual

uses sight to communicate

References

Howell, B. L. and N. M. Maggiulli. Conservation assessment for the cascade torrent salamander (Rhyacotriton cascadae). None. Oregon/Washington: USDA Forest Service Region 6 and USDI Bureau of Land Management Interagency Special Status and Sensitive Species Program. 2011.

Benke, A., C. Cushing. 2005. Rivers of North America. Thobald's Road, London: Elsevier Academic Press.

Bridges, C. 1999. Effects of a pesticide on tadpole activity and predator avoidance behavior. Journal of Herpetology, 33/2: 303-306.

Corn, P., R. Bury. 1988. Responses of aquatic and streamside amphibians to timber harvest: A review. Pp. 165-181 in K Raedeke, ed. Streamside Management: Riparian Wildlife and Forestry Interactions, Vol. No volume/59. Seattle, WA: College of Forest Resources, University of Washington. Accessed April 17, 2016 at http://www.fs.fed.us/rm/boise/AWAE/labs/awae_flagstaff/Hot_Topics/ripthreatbib/bury_corn_respaquaamph.pdf.

Corn, P., R. Bury. 1989. Logging in western Oregon: Responses of headwater habitats and stream amphibians. Forest Ecology and Management, 29/39: 39-57.

Davic, R., H. Welsh. 2004. On the ecological roles of salamanders. Annual Review of Ecology, Evolution, and Systematics, 34: 405-434.

Diller, L., R. Wallace. 1996. Distribution and habitat of Rhyacotriton variegatus in managed, young growth forests in North Coastal California. Journal of Herpetology, 30/2: 184-191.

Good, D., D. Wake. 1992. Geographic Variation and Speciation in the Torrent Salamanders of the Genus Rhyacotriton (Caudata: Rhyacotritonidae). United States: University of California.

Hammerson, G. 2004. "Rhyacotriton variegatus" (On-line). The IUCN Red List of Threatened Species 2004. Accessed January 26, 2016 at http://dx.doi.org/10.2305/IUCN.UK.2004.RLTS.T59438A11941672.en.

Hartwell, H., J. Welsh, A. Lind. 1996. Habitat correlates of the southern torrent salamander, Rhyacotriton variegatus (Caudata: Rhyacotritonidae), in northwestern California. Journal of Herpetology, 30/3: 385-398.

Karraker, N. 1999. Rhyacotriton variegatus (southern torrent salamander) nest site. Herpetological Review, 30/3: 160-161.

Karraker, N., L. Ollivier, G. Hodgson. 2004. Oviposition site of the southern torrent salamander (Rhyacotriton varigatus) in northwestern California. Northwestern Naturalist, 86/1: 34-36.

Lannoo, M. 2005. Amphibian Declines: The Conservation Status of United States Species. United States: University of California Press.

Leonard, W., H. Brown, L. Jones, K. McAllistar, R. Storm. 1993. Amphibians of Washington and Oregon. Seattle: Seattle Audubon.

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

Nussbaum, R., E. Broodie, R. Storm. 1983. Amphibians and Reptiles of the Pacific Northwest. Moscow, Idaho: University of Idaho Press.

Palmer, C., R. Watts, R. Gregg, M. McCall, L. Houck, R. Highton, A. Stevan. 2005. Lineage-specific differences in evolutionary mode in a salamander courtship pheromone. Molecular Biology and Evolution, 22/11: 2243-2256.

Petranka, J. 1998. Salamanders of the United States and Canada. Washington and London: Smithsonian Institution Press.

Rundio, D., D. Olson. 2001. Palatability of southern torrent salamander (Rhyacotriton variegatus) larvae to Pacific giant salamander (Dicamptodon tenebrosus) larvae. Journal of Herpetology, 35/1: 133-136.

Sever, D., C. Tait, L. Diller, L. Burkholder. 2004. Ultrastructure of the annual cycle of female sperm storage in spermathecae of the torrent salamander, Rhyacotriton variegatus (Amphibia: Rhyacotritonidae). Journal of Morphology, 261/1: 1-17.

Stebbins, R., N. Cohen. 1997. A Natural History of Amphibians. Princeton, New Jersey: Princeton University Press.

Tait, C., L. Diller. 2006. Life history of the southern torrent salamander (Rhyacotriton variegatus) in coastal northern California. Journal of Herpetology, 40/1: 43-54.

Wells, K. 2007. The Ecology & Behavior of Amphibians. United States: The University of Chicago.

Welsh Jr., H., A. Lind. 1996. Habitat correlates of the southern torrent salamander, Rhyacotriton variegatus (Caudata: Rhyacotritonidae), in Northwestern California. Journal of Herpetology, 30/3: 385-398.

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