Plethodon larselli

A small terrestrial salamander. The sides are dark brown to black with white flecks, and a mid-dorsal stripe varies from red to chestnut. Black pigment in the dorsal stripe may be small spots or chevrons (^). The stripe runs from the head to the tip of the tail. The venter is salmon-pink or reddish with black specks. The outer toe of the hind foot is small. Adults reach sizes of 35-55 mm snout to vent length (75-100 mm total lengh). Females reach larger adult sizes than males (50 vs. 45 mm SVL). Modal number of costal grooves is 15. Males lack mental glands. Hatchlings are 17-18 mm SVL (Brodie 1970; Leonard et al. 1993; Petranka 1998).

Plethodon larselli may be distinguished from other Pacific Northwest species of Plethodon by the reddish coloration of the venter, the dorsal stripe which extends to the tail tip, and the small size of the outer toe on the hind feet (Stebbins 1985; Leonard et al. 1993).

A restricted range in the Columbia River gorge of Oregon and Washington, and north in the Cascade Mountains to the vicinity of Mt. St. Helens, Washington.Salamanders inhabit mesic talus slopes, and other rocky areas. Animals are frequently found among talus and gravel. Most populations are found in humid mixed forests of Douglas Fir and hardwoods (Leonard et al. 1993; Petranka 1998).

This species can be found in the USA along the Columbia River Gorge in the Washington and Oregon Cascades, and as four populations near Mount Saint Helens and just south of Mount Rainier. It is found at altitudes up to 1,036m asl (Leonard et al. 1993).

endemic to a single nation

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (5000-20,000 square km (about 2000-8000 square miles)) Columbia River Gorge in southern Washington and northern Oregon and discontinuously northward in the Cascades to central Washington (to at least Snoqualmie Pass-Kachess Lake area) (Leonard et al. 1993, Petranka 1998, Stebbins 2003). Elevational range extends to around 3,900 feet (Stebbins 2003).

The southern end of the range is roughly defined by the towns of Hood River and Troutdale, Oregon. In Washington, the species occurs in the Western Cascades Physiographic Province, with the main distribution along a 58-km stretch of the Columbia River Gorge; additional, isolated populations occur in the Cascade Range; documented in Clark, Skamania, Lewis, King, Klickitat and Kittitas Counties; population distribution within the range is patchy (Hallock and McAllister 2002).

Length: 10 cm

Habitat and Ecology

Systems

• Terrestrial

Comments: This salamander inhabits steep, forested (e.g., Douglas-fir and mixed hardwoods) or nonforested slopes associated with talus, scree, gravelly soils, or other rocky substrates where interstitial spaces exist between the rock and soil (Hallock and McAllister 2002). Columbia River Gorge sites are almost exclusively on talus slopes formed from lava flows (Petranka 1998). Nonforested sites often are north-facing and mossy. In some areas of the Cascade Mountains in Washington, habitats include old-growth coniferous forests without significant exposed rocky areas, as well as lava tubes near Mount St. Helens (Aubrey et al. 1987, Hallock and McAllister 2002). Important microhabitats are under rocks, woody debris, or leaf litter (Hallock and McAllister 2002, Stebbins 2003). Moves deep under talus in cold or dry/hot weather.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Sedentary habits and very specific habitat requirements may hinder dispersal; colonization of suitable, unoccupied habitat may be difficult if the habitat is far from existing populations (Dumas 1956, Herrington and Larsen 1983).

Even with this species' small distribution, at least four populations have been shown to be genetically distinct, arguing that there is little gene flow between populations (Howard et al. 1983).

Comments: Feeds on a variety of invertebrates especially mites and collembolans. Diet of larger individuals is more varied and includes snails and earthworms, which are not eaten by juveniles (Nussbaum et al. 1983).

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 21 - 80

Comments: Washington Department of Fish and Wildlife had 67 unique records for this species as of 1997 (Dvornich et al. 1997; see also Washington Herp Atlas 2002). Populations in most of these sites are expected to be extant, though some of them may be combined into single occurrences. There are approximately 15 populations in Oregon (ORHP 1998).

Unknown

Comments: Total adult population size is unknown. Locally abundant across the majority of the range (Charles M. Crisafulli, unpublished data).

Found in association with P. VEHICULUM in Washington and P. DUNNI in Oregon.

Comments: Inactive in cold temperatures and hot, dry weather.

Surface activity occurs whenever moisture and temperature conditions are appropriate, primarily in the spring and fall. In the Columbia River Gorge, most activity occurs from mid-February through late-May and in the fall from late September through late-November (Herpetology Northwest 2004). In the Cascade Range, the activity period is approximately April through late June and late September to late November (Herpetology Northwest 2004).

Breeds mainly in fall. Eggs are laid in late winter-early spring. Clutch size is 2-12, average 7. Eggs hatch probably in about 4 months. Males are sexually mature in 3-3.5 years. Females deposit their first clutch at 4 years or older. Female reproductive cycle lasts 2 years or more.

Year Assessed

Assessor/s

Reviewer/s

Justification

History

• 1996
  Data Deficient
• 1994
  Vulnerable
  (Groombridge 1994)
• 1990
  Indeterminate
  (IUCN 1990)
• 1988
  Indeterminate
  (IUCN Conservation Monitoring Centre 1988)
• 1986
  Indeterminate
  (IUCN Conservation Monitoring Centre 1986)

United States

Rounded National Status Rank: N3 - Vulnerable

Rounded Global Status Rank: G3 - Vulnerable

Reasons: Small range in Oregon and Washington; several occurrences are protected, but moderate threats from habitat alteration exist elsewhere.

Intrinsic Vulnerability: Moderately vulnerable

Comments: Sites support high abundance and small population effects are not expected to influence
persistence.

Environmental Specificity: Very narrow to narrow.

Like other members of the genus Plethodon, P. larselli is completely terrestrial through all stages of its life history; courtship, mating, and egg deposition occur on land. There is no free living larval stage, and juveniles hatch completely metamorphosed (Stebbins 1985; Petranka 1998).Courtship behavior has not been described, but general facts are known based on closely related species. Fertilization occurs by means of a spermatophore deposited on the substrate by the male and picked up in the cloaca by the female (Duellman and Trueb 1986). Mating occurs during fall and spring months (Nussbaum et al. 1983; Herrington and Larsen 1987). Females may only breed every 2-3 years (Herrington and Larsen 1987). Nests have not been found, but females likely lay underground within talus, and tend the eggs until hatching in late summer or early autumn (Petranka 1998). Average clutch size is about 7 (Nussbaum et al. 1983; Herrington and Larsen 1987).

Diet is varied, including mites, collembolans, snails, annelids, spiders, beetles, and hymenopterans (Altig and Brodie 1971; Nussbaum et al. 1983). Likely predators of P. larselli include small snakes, birds, and small mammals. When molested, individuals rapidly coil and uncoil. This behavior may move them rapidly away from potential predators (Nussbaum et al. 1983; Petranka 1998).

Population

Population Trend

Global Short Term Trend: Relatively stable (=10% change)

Comments: Populations appear stable; new populations are being discovered in Washington (Lisa Hallock, pers. comm. , 1998).

Global Long Term Trend: Increase of 10-25% to decline of 30%

Comments: Likely relatively stable in extent of occurrence, probably less than 25% decline in population size, area of occurrence, and number/condition of occurrences.

Degree of Threat: Medium

Comments: Threatened by logging (changes microclimate and resources of talus slopes) and by use of talus for road construction; any ground-disturbing activity or land use that changes the moisture regimes and permeability of inhabited rocky substrates, such as overstory tree removal and gravel removal, may threaten populations (Herrington and Larsen 1985, Aubrey et al. 1987, Pfrender 1993, Leonard et al. 1993, Petranka 1998, Hallock and McAllister 2002).

Chemical applications (i.e., herbicides, pesticides, fertilizers) may affect salamanders directly due to toxicity or indirectly due to loss of prey-base (Hallock and McAllister 2002).

The talus slope habitat of many populations is extremely fragile (Leonard et al. 1993). Populations are also threatened by logging, and road building (which uses talus) (Petranka 1998).

Major Threats

Conservation Actions

Management Requirements: Maintain 40% canopy closure of trees within sites and within a buffer of at least one site-potential tree or 100 feet horizontal distance, whichever is greater, surrounding the site; larger buffer widths are appropriate upslope from protected sites on steep slopes; avoid disturbance of talus (Thomas et al. 1993).

Global Protection: Few to several (1-12) occurrences appropriately protected and managed

Comments: Most habitat is protected within the Columbia River National Scenic Area (Leonard et al. 1993). Habitat on national forest land may not be adequately protected.

Needs: Protect all known sites. See Bury et al. (1980) for general protection recommendations.