Olympic Torrent Salamander

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). 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).

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).

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).

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).

Olympic salamanders are Urodeles and, as such, can regenerate lost limbs.

Although there is no definite data on the matter, it is possible that males of this species utilize their cloacal vent glands in releasing pheromones to communicate with other individuals. Olympic salamanders also sense their environments through visual and tactile cues.

Communication Channels: visual ; chemical

Other Communication Modes: pheromones

Perception Channels: visual ; tactile ; chemical

The logging industry, common in the northwestern United States, is detrimental to the conservation of this species, as deforestation impacts the sedimentation of streams that these salamanders live in and around. Deforestation is also problematic, as the salamanders are found primarily in older forests due to the lack of necessary microhabitat conditions in deforested areas.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

As with most other salamanders, this species undergoes an aquatic juvenile phase, with external gills and a paddle-shaped tail. Olympic salamanders are approximately 13 mm upon hatching and typically grow to between 30.2 and 38.6 mm following metamophosis. Metamorphosis may occur at any time of year but is most common in late summer of the third year.

Development - Life Cycle: metamorphosis

Deforestation is detrimental to the conservation of Olympic salamanders, posing potential problems to the logging industry functioning throughout its habitat.

There are no known benefits to humans presented by this species.

Caudouterina rhyacotriton, an intestinal trematode, has been found in Olympic salamanders.

Commensal/Parasitic Species:

• Caudouterina rhyacotriton (Class Trematoda, Phylum Platyhelminthes)

These salamanders feed primarily upon insects such as springtails (Collembola), piptera, and stonefly (Plecoptera) nymphs. The have also been found to prey upon other aquatic life found in streams, such as amphipods.

Animal Foods: insects

Primary Diet: carnivore (Insectivore )

Olympic salamanders are found mainly in coastal areas of the Olympic Peninsula of Washington to northwestern Oregon. Some populations have also been found from southwestern Oregon to Mendicino County, California, and within the Cascade Mountains of Washington and Northern Oregon.

Biogeographic Regions: nearctic (Native )

Olympic salamanders live in humid climates within the forests of the coastal western United States, preferring cooler climates than most other salamanders. They are native to well-forested (largely coniferous) mountain ranges. Generally, they are found in and near streams or running water; they are rarely further than one meter from such an environment and are rarely found deeper than several millimeters under water. These salamanders are often found within moist cliff faces or under rock debris in stream beds.

Range elevation: 0 to 1200 m.

Average depth: less than one m.

Habitat Regions: temperate ; terrestrial ; freshwater

Terrestrial Biomes: taiga ; forest ; mountains

Aquatic Biomes: rivers and streams

There is currently no information available regarding the lifespan of Olympic salamanders; however, based on data from other Rhyacotriton species, they are assumed to have a moderately long lifespan of greater than 10 years.

Olympic salamanders are dark brown dorsally with white guanophore spots. They are usually yellow ventrally, with dark patches in some individuals. These salamanders typically range between 94 and 97 mm in length, with females being larger than males.

Range length: 94 to 97 mm.

Sexual Dimorphism: female larger

Other Physical Features: ectothermic ; bilateral symmetry

Although there are no confirmed predators of this species, garter snakes and giant salamanders are considered potential predators.

Known Predators:

• Giant salamander (Dicamptodontidae) sp.
• Garter snake (Thamnophis) sp.

Anti-predator Adaptations: aposematic

This species breeds year round, peaking in the Spring. Males are typically more aggressive during breeding periods and use a distinctive tail movement, where only the tail tip is moved, to attract the attention of females before depositing a spermatophore; females then grasp the spermatophore with theur cloacal lips and fertilization takes place internally. Courtship is presumed to take place on land or within the splash zone of streams.

Mating System: polygynandrous (promiscuous)

This species utilizes internal fertilization through cloacal spermatophores produced by the male and taken in by the female. Females may store spermatazoa in spermathecae and may mate with multiple males before laying egg clutches (though it is uncertain how common this is); this species likely mates more than once during a breeding season. They will not participate in courtship until they have reached sexual maturity. Eggs are typically deposited in creek or stream beds where they hatch. The embryonic period, including the time before hatching and after, when the embryo is still feeding on the egg yolk, is estimated at 360 days. Larvae can be as small as 13.5 mm and individuals begin to metamorphose into juveniles between 4-5 years of age (38-26 mm). During metamorphosis, larvae lose their gill slits and external gills.

Breeding interval: This species generally breeds once yearly.

Breeding season: Breeding season peaks in May, but exact breeding time varies considerably on an individual basis.

Range number of offspring: 2 to 16.

Average number of offspring: 8.

Range time to hatching: 210 to 295 days.

Range age at sexual or reproductive maturity (female): 4 to 5 years.

Range age at sexual or reproductive maturity (male): 4 to 5 years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous ; sperm-storing

Due to the inaccessibility of nests to predators, there is little need for parental care in this species; additionally, due to the long period between egg laying and the larval stage, it would be nearly impossible for a female to remain with her nest and care for young. This trait varies from the typical situation in salamanders, as oophagy is common among many other species. The eggs produced by Olympic salamanders are large (in comparison to those produced by other salamanders), few in number, and are unpigmented. The characteristicly large eggs are consistent with a lack of parental care; however, the relatively small number of eggs produced is further evidence that they are deposited in a location safe from predation.

Parental Investment: no parental involvement

The Olympic torrent salamander (Rhyacotriton olympicus) is a species of salamander in the family Rhyacotritonidae. This is a small salamander (up to 10 cm total length) that lives in clear, cold, mountain streams. It is medium to dark brown and may have a few small light spots on the sides and small dark spots on the tail; it is bright yellow on the belly, usually with some dark spots. Torrent salamanders typically have short snouts and relatively large eyes. As in other torrent salamanders, adult males have square-edged lobes behind the cloaca. These salamanders live at the edges of clear, cold, mountain streams; they can be abundant under gravel at stream edges and in the spray zones of waterfalls. During rainy seasons, they are occasionally found under objects on land away from streams.

Its natural habitats are temperate forests, rivers, and freshwater springs. It is threatened by habitat loss.