Hell Hollow Slender Salamander
© 2013 Stephen Nyman (1 of 13)
Batrachoseps diabolicus Jockusch, Wake and Yanev, 1998
Robert W. Hansen1
1. Historical versus Current Distribution. Hell Hollow slender salamanders (Batrachoseps diabolicus) are found on the western slope foothills of the Sierra Nevada of California, from the lower Merced River Canyon (Mariposa County) north to the American River (Placer County) (Jockusch et al., 1998), at elevations below 620 m. Recent work by Jockusch et al. (1998) partitioned the formerly wide-ranging Batrachoseps relictus of the Sierra Nevada into four species (from north to south in the central and southern Sierra Nevada): B. diabolicus, Kings River slender salamanders (B. regius), Sequoia slender salamanders (B. kawia), and relictual slender salamanders (B. relictus). Of these species, B. diabolicus has a relatively extensive distribution and is known from at least a dozen localities.
2. Historical versus Current Abundance. Based upon limited sampling, populations from the Merced River Canyon appear stable. There is little information concerning the status of more northern populations, as these have been recognized only recently as B. diabolicus.
3. Life History Features.
A. Breeding. Reproduction is terrestrial.
i. Breeding migrations. Unknown.
ii. Breeding habitat. Unknown. Presumably, courtship occurs after the start of the rainy season in the fall; egg-laying probably takes place from November–January, depending on local rainfall.
i. Egg deposition sites. Nest sites have not been found in Hell Hollow slender salamanders. At several sites (for example at the type locality), salamanders are associated with extensive metamorphic rock talus; presumably eggs are laid well underground.
ii. Clutch size. Unknown.
C. Direct Development. Newly hatched salamanders were observed on 8 February at Hell Hollow (R.W.H., unpublished data). Onset of fall/winter rains in this part of the Sierra Nevada is unpredictable and varies from year to year; thus, timing of hatching is expected to vary both geographically and annually.
D. Juvenile Habitat. Hatchling-sized individuals have been found in the same general areas as adults, but often under smaller pieces of cover.
E. Adult Habitat. Hell Hollow slender salamanders are found mostly in mixed pine-oak woodland and chaparral communities of the foothills of the Sierra Nevada, often at low elevations where the foothills first appear, in areas of extreme summer heat and drought.
At Hell Hollow in the lower part of the Merced River Canyon (ca. 300 m elevation), salamanders are found beneath metamorphic rocks (often occurring in patches of talus), bark rubble, and downed logs, usually in areas that receive little direct sunlight during the winter. Prominent components of the local vegetation include foothill pine, interior live oak, California buckeye, California bay, and toyon.
At one site at the northern end of their range (near the Middle Fork of the American River, El Dorado County; 245 m elevation), salamanders were found in a narrow, shaded ravine containing a small stream, with limestone outcrops and rubble. Vegetation included canyon live oak, bigleaf maple, California bay, and Douglas fir; the ground was covered with mosses and ferns. Salamanders were obtained from under bark layers on fallen logs, as well as beneath rocks, in areas of shade or filtered sunlight. At lower elevations in the same region (ca. 100 m elevation), the salamanders have been taken in open pastures under rocks.
F. Home Range Size. Unknown.
G. Territories. Unknown.
H. Aestivation/Avoiding Dessication. Salamanders are present under surface cover only during periods of adequate soil moisture—generally from November–March/April. Timing of surface activity varies depending on arrival of fall/winter rains. Individual salamanders presumably move beneath the surface in burrows or rock rubble during dry periods and during episodes of extreme cold. Field body temperatures of salamanders found under cover averaged 8.5 ˚C (range = 6.0–12.9 ˚C; n = 11; R.W.H., unpublished data).
I. Seasonal Migrations. Unknown.
J. Torpor (Hibernation). We have not recorded surface activity at substrate temperatures below 6 ˚C.
K. Interspecific Associations/Exclusions. Hell Hollow slender salamanders occur in association with limestone salamanders (Hydromantes brunus), arboreal salamanders (Aneides lugubris), yellow-eyed ensatinas (Ensatina eschscholtzii xanthoptica), and California newts (Taricha torosa) within the Merced River Canyon, and with these species (except for limestone salamanders) and California slender salamanders (Batrachoseps attenuatus) at localities farther north. At the northern end of their range at the American River, Hell Hollow slender salamanders are sympatric with California slender salamanders (Jockusch et al., 1998)—the only confirmed instance of sympatry between these two species—although information concerning their local distribution and habitat characteristics is unknown. The ranges of these congeners overlap considerably and they undoubtedly occur in local sympatry at many places. Within the Hell Hollow area of the Merced River Canyon, Hell Hollow slender salamanders are often found in proximity to individuals of limestone salamanders; however, the latter are nearly always associated with moist talus, while Hell Hollow slender salamanders range into the surrounding chaparral.
L. Age/Size at Reproductive Maturity. This is a moderately small species of Batrachoseps, with adults ≤ 45 mm SVL (Jockusch et al., 1998). Age and size at sexual maturity are unknown.
M. Longevity. Unknown.
N. Feeding Behavior. Has not been described, although all Batrachoseps species observed thus far use a projectile tongue to capture small invertebrates.
O. Predators. Predation has not been observed. Ring-necked snakes (Diadophis punctatus) occur throughout the range of Hell Hollow slender salamanders, and the two species have been found meters apart at Hell Hollow.
P. Anti-Predator Mechanisms. Immobility, coiling, and rapid crawling have all been observed when salamanders are first uncovered (R.W.H., unpublished data). There does not seem to be a prevalent, stereotypical response. The dark dorsal and ventral coloration renders them effectively cryptic when uncovered.
Q. Diseases. Unknown.
R. Parasites. Unknown.
S. Comments. Until the work of Yanev (1978, 1980), Jockusch (1996), and Jockusch et al. (1998), taxonomic relationships among Batrachoseps in the central and northern Sierra Nevada were poorly resolved; thus, some earlier references (e.g., Basey, 1969, 1976; Basey and Sinclear, 1980) did not make distinctions among the three species of Batrachoseps now known to occur in this region: B. attenuatus, B. diabolicus, and B. gregarius. Moreover, specimens from this part of the Sierra Nevada in some institutional collections have typically been identified as B. attenuatus, and it is not clear which species are actually represented; reliance on locality for species identification is not possible in many instances.
Batrachoseps diabolicus shows substantial geographic variation in mtDNA sequences (cytochrome b). Jockusch et al. (1998) found five haplotypes falling into two clades which differ by 8.0–11.8%. This is substantial divergence, suggesting that > 1 species might be represented. One of these clades has been found only in Calaveras County, whereas the other clade occurs throughout the entire range of the species.
4. Conservation. Salamanders of the genus Batrachoseps can be difficult to locate in the central and northern Sierra Nevada, a region home to three species: B. attenuatus, B. diabolicus, and B. gregarius (which reaches its northern range limits near the southern boundary of B. diabolicus). Salamanders are absent from large areas of apparently suitable habitat and are seldom common where encountered. These factors, together with the difficulty of making species identifications in the field, have hampered field studies. Thus, detailed knowledge of distribution, habitat associations, and other aspects of the natural history of these species is fragmentary.
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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