Siskiyou Mountains Salamander

A short-limbed, long-bodied salamander, closely resembling Plethodon elongatus (Del Norte Salamander). Juveniles have an even-edged, olive-tan dorsal stripe. In adults, the dorsal stripe appears light brown due to a light, uniform covering of melanophores. The dorsal stripe usually extends to the middle portion of the tail. Ground and ventral coloration is black in small juveniles, but lighter in adults, where it appears purplish-brown in dorsal ground color and lavender to light purplish-gray on the venter. The gular region is cream-colored, copper-colored iridophores are present beneath the stripe (may lend an orange or pink tone to the stripe), and heavy iridophore flecking appears on the head, sides, and limbs. Moderate iridophore flecking is present along the dorsal stripe and in the gular area. Iridophores are absent or very sparse along the midventral line. Some rare individuals have a few gold iridophores on the eye, above the pupil. Sexual dimorphism is apparent in the number of maxillary and pre-maxillary teeth, with males having an average of 47.4 maxillary and pre-maxillary teeth, and females averaging 53.9. Also, males have mental glands, and, sometimes, poorly developed vent lobes (Brodie 1973). P. elongatus differs from P. stormi in having a reddish dorsal stripe and sparse or absent dorsal iridophore flecking. P. elongatus also has shorter legs, fewer teeth, and a narrower, longer head (Brodie 1971), as well as more intercostal folds between adpressed limbs (5-6 for P. elongatus, 4-5 for P. stormi, and 2.5-3.5 for P. asupak) (Mead et al. 2005). P. asupak is more robust than either P. elongatus or P. stormi, with a wider head and longer limbs (Mead et al. 2005).Individuals from southern Oregon and northern California are virtually identical in coloration and patterning, but local populations sometimes vary in the modal number of costal grooves (Brodie 1970; Nussbaum et al. 1983).Although it had been debated whether the Siskiyou Mountains salamander should be designated as its own species or be included under within P. elongatus (Palazzo 1994), both molecular and morphological analysis confirm that P. stormi is a distinct species from P. elongatus, and from a third and recently named Siskiyou salamander species, P. asupak (Mead et al. 2005).Named in honor of Robert M. Storm, Professor of Zoology at Oregon St. University, who directed the field trip in which the first specimens were found(Brodie 1971). See another account at californiaherps.com (http://www.californiaherps.com/salamanders/pages/p.stormi.html).

The historical range is unknown, and it is currently found only in the Siskiyou Mountains of northern California and southern Oregon, mostly in the Seiad Valley in the Klamath River Drainage of Northern Siskiyou County and in the Applegate River drainage in southern Oregon (Nussbaum et al. 1983; Stebbins 1985; Palazzo 1994). P. stormi is almost always found near talus slopes or rocky crevices. However, during the wettest months of the year, it moves into the surrounding forest and lives under bark, logs, and other debris. The densest populations live on heavily forested, north facing slopes with talus (Petranka 1998).

Sexually mature at a snout-vent length of about 55 mm (Brodie 1971) and an age of 5-6 years (Nussbaum et al. 1983). Males have been found with sperm in their vasa deferentia in autumn and spring, suggesting that mating occurs around this time (Nussbaum et al. 1983). Females seem to breed biennially (every other year), and no one has ever found a nest (Petranka 1998). Indirect evidence suggests that females lay their eggs in the spring, and brood them in underground nests deep within talus throughout the summer. Mature ova are white and measure 4.2-5.2 mm in diameter. The number of mature ova in gravid females varies from 2 to 18 and averages 9 (n=37), but does not correlate with female body size. Hatching probably takes place in the fall, but hatchlings do not surface until the following spring. Juveniles and females grow 6.5 and 8.0 mm, respectively, in snout-vent length per year. The most heightened activity on the surface occurs in March-April and September to early November. In summer, they remain below ground during the day, but move to surface sites at night to feed on invertebrates. During dry weather, they will stay at the entrance of an underground retreat, darting forward regularly to catch prey (Nussbaum et al. 1983). In wet weather, they will emerge completely, and in conditions of 100% humidity they will move freely on rock surfaces (Palazzo 1994). Their diet includes spiders, psuedoscorpions, ites, ants, collembolans, and beetles (Nussbaum et al. 1983).

The combination of this salamander's specialized habitat requirements and its limited geographic range make it sensitive to environmental disturbance (Petranka 1998). The clear-cutting of trees adjacent to the talus slopes and rocky outcrops is a serious threat to P. stormi, whose continually shaded, moist microclimate requires a canopy closure of no less than 70%. In addition, the filling of Applegate Reservoir in the mid 1970's flooded a small portion of their range within Oregon. In 1971, P. stormi was named as a rare species by the California Fish and Game Comission, and soon after it was designated as Threatened. Surveys of the Klamath National Forest in the late 1970's detected no salamanders, even in viable habitat. However, dry weather may have been responsible for their absence rather than any permanent population trend. In the spring of 1994, state and federal agents, as well as a private lumber company, started a 2-year study to determine the salamander's range, distribution, and habitat requirements. Additionally, officials at the Rogue River National Forest in Oregon began developing a management plan in 1994 for conservation of P. stormi within the National Forests. Pallazo (1994) suggests that in known P. stormi habitat, restricting logging between July and August, when all the salamanders remain underground, would greatly help conservation. Also, temporary cessation of harvesting would need to occur after rainfall of 1 inch or more, since the salamanders emerge during such moist conditions. Palazzo (1994) stipulates that if continual logging is allowed, the ecological alteration incurred will destroy the salamander's habitat. Welsh et al. (2007) showed that optimal habitat for Plethodon stormi consisted of less disturbed mature to late seral forest with closed canopy, moist and relatively warm microclimates, deep leaf litter, and cobble to boulder-sized rock substrates. Conserving interconnected stands of mature forest across the geographical range of this species would likely best insure its long-term viability (Welsh et al. 2007).

The Siskiyou Mountains salamander (Plethodon stormi), also called the Siskiyou Mountain salamander, exists only in isolated locations along the Klamath River in northern California and southern Oregon. It is a close relative of the Del Norte salamander, and some herpetologists believe it may be a subspecies of that animal.