Relictual Slender Salamander
|Taxonomic Notes: This species has a complicated history. Brame and Murray (1968, Bull Nat Hist Mus Los Angeles Co) named the species and assigned to it populations from the Kern Canyon (the type locality) and the southern Sierra Nevada (west of the Kern River), the central California Coastal region, Santa Cruz Island, and Sierra San Pedro Martir in Baja California, Mexico. The population at the type locality and those in lower Kern Canyon disappeared by the early 1970s and tissues were unavailable for molecular studies, complicating the subsequent history of the taxon. Discovery of populations on Breckenridge Mtn, south of the lower Kern River, that were slightly different (more trunk vertebrae) than those at the much lower elevation type locality, led to years of speculation that they might be members of a new species, since that population was genetically distinct. Yanev (1979, in Power, ed. The California Islands) showed that central coastal populations belonged to different species, subsequently named as B. gavilanensis, B. luciae, B. incognitus and B. minor by Jockusch, Yanev and Wake (2001, Contrb Sci Nat Hist Mus Los Angeles Co), and assigned the Santa Cruz Island population to B. nigriventris. The Sierra San Pedro Martir population was shown to be assignable to B. major by Martinez-Solano, Peralta-Garcia, Jockusch, Wake, Vaszquez-Dominguez and Parra-Olea (2012 Mol Phyl Evol). The populations in the Sierra Nevada were placed in two new species, B. regius and B. kawia by Jockusch, Wake and Yanev (1998, Contrb Sci Nat Hist Mus Los Angeles Co), but the southernmost populations in the Greenhorn Mts were retained in B. relictus. The discovery of a population in the upper reaches of Lucas Creek, which flows into the lower Kern Canyon, enabled a molecular analysis by Jockusch, Martinez-Solano, Hansen and Wake (2012, Zootaxa), which determined that it and the Breckenridge Mtn populations are appropriately assigned to B. relictus. This, in turn, meant that the populations north and west of the Kern River, and one east of the Kern River on the Kern Plateau previously considered to be B. relictus were without a name. They were placed in a new taxon, Batrachoseps altasierrae in 2012.|
© 2012 William Flaxington (1 of 10)
Batrachoseps relictus Brame and Murray, 1968
Robert W. Hansen1
1. Historical versus Current Distribution. Relictual slender salamanders (Batrachoseps relictus; sensu Jockusch et al., 1998) are restricted to the west slopes of the southern Sierra Nevada of California, ranging from the lower Kern River Canyon (Kern County) to highlands drained by the Tule and Kern rivers (Tulare County). Two principal distributional units are present: (1) lower Kern River Canyon, where relictual slender salamanders have been found at six sites at elevations of 485–730 m (Brame and Murray, 1968); and (2) higher elevations in the Greenhorn Mountains north to the Tule River drainage, at elevations of 1,125–2,440 m. There is a single record for the western margin of the Kern Plateau, east of the Kern River, at 2,440 m (Hansen, 1980; Jockusch et al., 1998). Despite repeated and careful searches, the species has not been found in the lower Kern River Canyon since 1971 and is presumed extirpated from those localities (Jennings and Hayes, 1994a; Hansen, 1997; Jockusch et al., 1998).
2. Historical versus Current Abundance. Populations of relictual slender salamanders from throughout the range appear to be stable (with the aforementioned exception of the type locality and associated sites in the lower Kern River Canyon, where no individuals of this species have been found since 1971, despite concerted efforts to find them). The construction of State Route 178 along the lower, southern slopes of the Kern River Canyon severely impacted seepages and springs that once harbored relictual slender salamanders. Although specimens were collected at these sites for a number of years following highway construction, this loss of habitat may have initiated local population declines that finally reached non-sustainable levels (Hansen, 1988).
3. Life History Features.
A. Breeding. Reproduction is terrestrial.
i. Breeding migrations. Unknown.
ii. Breeding habitat. For the mid elevation populations (e.g., Tule River drainage, ≤ 1,250 m), courtship presumably occurs after the start of the rainy season in the fall (November, perhaps earlier), and egg-laying probably takes place in late November to December, depending on local rainfall and temperatures. Higher elevation sites (1,600–2,440 m) experience a wide range of winter conditions, including moderate snowfall and below freezing temperatures well into spring. Breeding phenology of these populations has not been studied.
i. Egg deposition sites. Nest sites of relictual slender salamanders have not been found. A large majority of populations are associated with seepages or springs, and we expect that nests will be found under rocks and logs at the margins of such wet microhabitats. Communal nests (Jockusch and Mahoney, 1997) are unknown for any member of the B. relictus species group.
ii. Clutch size. Unknown.
C. Direct Development. Timing of hatchling emergence is poorly known. Hatchlings were observed at one high-elevation site (1,820 m) in the Greenhorn Mountains on 28 May.
D. Juvenile Habitat. Unknown how this may differ from adult habitats.
E. Adult Habitat. At most localities where relictual slender salamanders have been found, they are associated with downed logs and bark rubble in moist conifer forest, frequently near seepages and springs where surface moisture persists through the summer. In the Greenhorn Mountains (Kern and Tulare counties), they are especially common in roadside seepages at elevations of 1,675–2,130 m. Typical forest components include Ponderosa pine, sugar pine, incense cedar, white fir, and black oak. We occasionally have found salamanders here beneath large sugar pine cones.
Farther north, near their lower elevation limits within the Tule River drainage (Tulare County, 1,215 m), relictual slender salamanders occur under rocks and logs beneath canyon live oaks in the transition to lower Ponderosa pine forest. Interestingly, several other species appear to reach their low elevation range limits within the Tule River Canyon at this site, including western skinks (Eumeces skiltonianus), northern alligator lizards (Elgaria coerulea), and rubber boas (Charina bottae); Gilbert's skinks (Eumeces gilberti) reach their uppermost point in the canyon here as well (R.W.H., unpublished data). At slightly higher elevation (1,265 m) in the same river canyon, relictual slender salamanders were found near a small creek in a forest of incense cedar, ponderosa and sugar pine, whitebark alder, bigleaf maple, and canyon live oak, under rocks, logs, and moist pine needles.
The single population east of the Kern River, located on the western flank of the Kern Plateau at an elevation of 2,440 m, is associated with a large seepage on a moderately steep slope, surrounded by a dense forest of Jeffrey pine and white fir. Relictual slender salamanders were found beneath rocks and downed logs that rested on saturated gravel substrates, some with surface flow (R.W.H., unpublished data).
The lower Kern River Canyon populations, now presumed extinct, were associated with perennial springs, seepages, and the margins of small creeks (Hilton, 1948; Brame and Murray, 1968). In this area, the species was taken in sympatry with yellow-blotched ensatinas (Ensatina eschscholtzii croceater) and Kern Canyon slender salamanders (B. simatus), though these two species are usually found away from water, whereas relictual slender salamanders frequently were found in water.
F. Home Range Size. Unknown.
G. Territories. Unknown.
H. Aestivation/Avoiding Dessication. Relictual slender salamanders are present under surface cover only during periods of adequate soil moisture. In mid elevation conifer forest, this may extend from April–November, especially for seep-margin populations. At lower elevations, the period of seasonal activity is shorter, beginning with rains in the fall and extending until May–June. Individual salamanders presumably move beneath the surface in burrows or rock rubble during dry periods and the coldest winter months. In the lower Kern River Canyon, where salamanders were closely associated with perennial seepages and springs, surface activity may have been possible over much of the year, as indicated by collection dates ranging from January–May. Field body temperatures for salamanders found under surface cover averaged 12.0 ˚C (range = 7.0–15.0 ˚C, n = 112; all data taken from populations ≥ 1,200 m elevation; R.W.H., unpublished data).
I. Seasonal Migrations. Unknown.
J. Torpor (Hibernation). We have not recorded surface activity of relictual slender salamanders at substrate temperatures below 7 ˚C.
K. Interspecific Associations/Exclusions. Over most of their range, relictual slender salamanders do not occur with any other species of Batrachoseps. Exceptions occur in the lower Kern River Canyon, at least historically, where relictual slender salamanders were sympatric with Kern Canyon slender salamanders (B. simatus) at two known sites (Brame and Murray, 1968). The ranges of relictual slender salamanders and gregarious slender salamanders (B. gregarius) converge in a number of drainages in the southern Sierra Nevada, but cases of sympatry are unknown. The single record for east of the Kern River is close to populations of Kern Plateau salamanders (B. robustus), and sympatry is expected (Wake et al., 2002).
Sierra Nevada ensatinas (Ensatina eschscholtzii platensis) occur at or near most of the relictual slender salamander sites from the Greenhorn Mountains northward. Yellow-blotched ensatinas occur in the lower Kern River Canyon at historical localities for relictual slender salamanders. The ranges of California newts (Taricha torosa) and relictual slender salamanders overlap below 1,500 m in Tulare County.
L. Age/Size at Reproductive Maturity. Relictual slender salamanders are one of the smallest species in the genus. For a small series from the lower Kern River Canyon, sexually mature males averaged 31.2 mm SVL (range = 26.3–36.9 mm, n = 8), and females averaged 36.2 mm SVL (range = 33.3–41.7 mm, n = 9; Brame and Murray, 1968; Wake and colleagues, unpublished data). For the high elevation populations (Greenhorn Mountains, Kern and Tulare counties), adult sizes appear to be somewhat larger (mean = 39.4 mm SVL; range = 34.4–48.1, n = 16, sexes lumped; Brame and Murray, 1968; Wake and colleagues, unpublished data), but more data are needed from throughout the range.
M. Longevity. Unknown.
N. Feeding Behavior. Has not been described for relictual slender salamanders, although all Batrachoseps species observed thus far use a projectile tongue to capture small invertebrates.
O. Predators. Predation on relictual slender salamanders is undocumented. Ring-necked snakes (Diadophis punctatus) are common in some parts of their range (e.g., Tule River) and are likely predators.
P. Anti-Predator Mechanisms. Defensive behaviors include coiling, immobility, thrashing, crypsis, and tail autotomy. Coiling behavior upon discovery is nearly universal among salamanders in a Tule River population. This behavior is uncommon among Greenhorn Mountains individuals, which are more likely to remain immobile or thrash vigorously when uncovered or touched (R.W.H., unpublished data). One individual escaped by crawling quickly down a tunnel beneath its rock.
There is a strong resemblance between Greenhorn Mountains relictual slender salamanders and a sympatric millipede. Although the salamanders display some variation, one common color pattern in the Greenhorns is that of a tan/brown dorsum with a thin, gray/black dorsal line—remarkably similar to that of the millipedes. Millipedes appear to prefer slightly drier substrates, but often both salamanders and millipedes are encountered under the same piece of cover (R.W.H., unpublished data). The noxious discharges of millipedes are well known; the effects of relictual slender salamander skin secretions are unstudied. Examples of vertebrate mimicry of millipedes have been offered by Vitt (1992) and Leonard and Stebbins (1999), and this may represent an additional occurrence. Alternatively, this may be a case of convergent crypsis, as the color patterns of both salamanders and millipedes well match the mixture of pine needles and incense cedar debris at seep margins. Mimicry of a noxious model and pattern selection for crypsis are not mutually exclusive hypotheses.
Q. Diseases. Unknown.
R. Parasites. Unknown.
S. Comments. The taxonomic composition of B. relictus has changed considerably following its description in 1968. Yanev (1978, 1980) removed coastal California populations from this species and restricted B. relictus to the Sierra Nevada, while noting extensive genetic subdivision across various Sierran drainages. Later, Jockusch et al. (1998) further partitioned this still wide-ranging group into four species (from north to south in the central and southern Sierra Nevada): B. diabolicus, B. regius, B. kawia, and B. relictus.
The lack of live material from the type locality and nearby areas in the lower Kern River Canyon, where B. relictus is presumed extinct, has precluded genetic comparisons with high elevation Greenhorn Mountains populations included in the species. Morphological and ecological differences exist between these two segments of the range, and it is possible that > 1 species is represented. Genetic divergence among high elevation populations of B. relictus is low relative to other species within the relictus group (Jockusch and Wake, 2002), suggesting that these populations have been in recent genetic contact.
4. Conservation. The lower Kern River Canyon populations (inclusive of the type locality), as described above, appear to have been extirpated. Despite our failure to locate specimens from this area over the last 30+ yr, additional search efforts are warranted. Although these historical localities occur on public lands administered by the USDA Forest Service, road margin habitat has been severely degraded by road maintenance and related construction activities. Relictual slender salamanders are a Species of Special Concern (California Department of Fish and Game), a Forest Service Sensitive Species, and a Federal Species of Concern.
1 Robert W. Hansen
2 David B. Wake
Literature references for Amphibian Declines: The Conservation Status of United States Species, edited by Michael Lannoo, are here.
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Citation: AmphibiaWeb. 2020. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 24 Nov 2020.
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