Ouachita Dusky Salamander
© 2009 Richard D. Bartlett (1 of 15)
Country distribution from AmphibiaWeb's database: United States
Desmognathus brimleyorum Stejneger, 1895
D. Bruce Means1
1. Historical versus Current Distribution. The current distribution of Ouachita Mountain dusky salamanders (Desmognathus brimleyorum) is highland areas south of the Arkansas River, including all the Ouachita Mountains and Petit Jean Mountain in western Arkansas; Rich, Winding Stair, Blackfork, and Kiamichi mountains, and the Potato Hills in eastern Oklahoma (Means, 1999b). This species is also found in small streams in the rugged topography south of Kiamichi Mountain along the Arkansas–Oklahoma border to Beaver Bend State Park in McCurtain County, Oklahoma, and also southeast of Little Rock, Arkansas (Means, 1999b). They have not been found on Iron Fork Mountain, the westernmost of the Ouachita Mountains in Oklahoma, but Chaney (1958) reported the only population known north of the Arkansas River at Russellville in Arkansas. It is not known whether the historical distribution was different from the current distribution.
2. Historical versus Current Abundance. No studies have been undertaken specifically to assess changes over time of known populations, but three robust populations on Rich Mountain in the 1970s were nearly devoid of salamanders in 1998 (personal observation). The reason, however, may have been a severe drought that had dried up all surface water and may have caused Ouachita Mountain dusky salamanders to retreat underground into the interstices of the rocky soils there. The practice of harvesting Ouachita Mountain dusky salamanders for fish bait has increased in the past two decades (personal observation) and could have a severe effect on local populations.
3. Life History Features.
A. Breeding. Reproduction is semi-aquatic. Eggs are laid on land and incubated by the female. Hatchlings move into water, and larvae are strictly aquatic.
i. Breeding migrations. Unknown, but see below. Oviposition occurs in late June and early July on Rich, Kiamichi, and the Cossatot mountains (Means, 1975b). Strecker (1908a) reported eggs in late August and early September near Hot Springs, Arkansas. Chaney (1958) found eggs in late stages of development at Russellville, Arkansas, on 12 October. Trauth (1988) and Taylor et al. (1990) reported finding eggs in July and August on Fourche, Winding Stair, and the Cossatot mountains, and Trauth (1988) described three stages of development in three egg clutches he excavated on Rich Mountain. Means (1975b) reported hatching on Rich, Kiamichi, and the Cossatot mountains in the second week of September, when 42 of 92 clutches collected at that time hatched immediately or after only a few minutes post collection; the remaining 50 clutches were about 3/4 developed. No egg clutches were found after late November (Means, 1975b). Hatching was reported on 12 October in the Russellville, Arkansas, population, but large larvae were also present and common, indicating that many had hatched sometime earlier (Chaney, 1958).
ii. Breeding habitats. Same as adult habitat.
i. Egg deposition sites. Eggs are laid most commonly under the surface of rocks, sometimes totally immersed in water and sometimes in air, and always with a brooding female (Chaney, 1958; Means, 1975b). Trauth (1988) reported on three egg masses he excavated 0.5 m deep near the water table of a dry seepage site in mud during a summer drought. The clutches were deposited in grape-like clusters on the ceiling of mud chambers made by females.
ii. Clutch size. Reported numbers range from 20–29 eggs (Trauth, 1988; Taylor et al., 1990; Trauth et al., 1990).
i. Length of larval stage. Perhaps 1 yr (Means, 1974; Trauth et al., 1990).
ii. Larval requirements.
a. Food. Unknown, but larvae are undoubtedly carnivorous.
b. Cover. Larvae use interstitial spaces among gravel, rocks, and organic litter in the streambed.
iii. Larval polymorphisms. None known.
iv. Features of metamorphosis. Unknown.
v. Post-metamorphic migrations. Unknown.
vi. Neoteny. All larvae completely metamorphose into morphologically terrestrial adults.
On Rich, Kiamichi, and the Cossatot mountains, collections in March and April contained a larger percentage of larvae than newly metamorphosed animals; by the end of June, metamorphosed animals made up the youngest age/size class, and only a few larvae remained (Means, 1975b). Trauth et al. (1990) stated that by mid August transformation had occurred. Metamorphosis occurred from 15 July–1 September in Russellville (Chaney, 1958).
D. Juvenile Habitat. Same as adult habitat, but animals are found wedged in between smaller crevices in gravel and rocks (Means, 1974, 1975b). Post-metamorphic growth was described by Chaney (1958) in the Russellville population and Means (1975b) from Rich, Kiamichi, and the Cossatot mountains.
E. Adult Habitat. Ouachita Mountain dusky salamanders are found most often and abundantly in first- and second-order mountain streams and adjacent ravine woodlands, especially where there is a rocky, gravelly, porous substrate. Rocky, coarse-gravelled stream benches, islands, and cascades are most densely populated. Where hillsides near streams are composed of coarse, rocky talus, adults may be found at night up to several tens of meters away from the streamside with their heads and anterior bodies protruding from crevices between rocks (Means, 1974, 1975b). Animals have also been collected from beneath rocks and from the banks of a spring (Chaney, 1958).
F. Home Range Size. Unknown, but densities during oviposition season (late June to July) ranged from 1.8 to an astounding 61.7 individuals/m2 of habitat (Means, 1975b).
G. Territories. Probably exist in this sedentary species, but have not been studied.
H. Aestivation/Avoiding Dessication. During droughts when surface water dries up in mountain streams, Ouachita Mountain dusky salamanders become difficult to find, presumably because they move downward into rocky substrata and talus slopes to avoid desiccation (personal observations). It is not known whether physiological changes take place during these periods.
I. Seasonal Migrations. At night, gravid females were observed moving over a wooded talus hillside and a gravel road on Rich Mountain and across a paved, macadam road in the Cossatot Mountains, moving both away and toward streamsides and up and down slopes (Means, 1975b).
J. Torpor (Hibernation). Specimens collected in mid winter were sluggish because their bodies were immersed in near-freezing water, but they became active when warmed (personal observation).
K. Interspecific Associations/Exclusions. Ouachita Mountain dusky salamanders are often found in mountain brooks with many-ribbed salamanders (Eurycea multiplicata), and the adjacent terrestrial habitat usually contains northern slimy salamanders (P. glutinosus) and either Caddo Mountain salamanders (Plethodon caddoensis) or Rich Mountain salamanders (P. ouachitae) (personal observation).
L. Age/Size at Reproductive Maturity. Males and females at Russellville, Arkansas, attain sexual maturity in their fourth year of growth and had attained a minimum SVL of 50.7 mm and 52.0 mm, respectively (Chaney, 1958). Means (1975b) reported age at sexual maturity as 3 yr for males and 4 yr for females, on each of Rich, Kiamichi, and the Cossatot mountains.
M. Longevity. Unknown.
N. Feeding Behavior. Food items found in the stomachs of 48 out of 64 Ouachita Mountain dusky salamanders from Russellville, Arkansas, were Licereus sp. isopods, spiders, lepidopteran larvae, buprestid beetles, collembolans, larval chironomids, plecopterans, hydrophilid beetles, centipedes, and adult dipterans (Chaney, 1958).
O. Predators. Documented predators are western cottonmouths (Agkistrodon piscivorus conanti; reported by Means, in Gloyd and Conant, 1990) and speckled kingsnakes (Lampropeltis getula holbrooki; reported by Trauth and McAllister, 1995). Potential other predators observed in the habitat were spotted skunks, raccoons, garter snakes, and large crayfish (Means, 1975b). Cannibalism on larvae was documented by Chaney (1958).
P. Anti-Predator Mechanisms. None known except that, as in desmognathine salamanders, in general, Ouachita Mountain dusky salamanders twist and flip their bodies with great power and agility when grasped, and jump and burrow rapidly into the substrate to escape and hide (personal observation).
Q. Diseases. An intraerythrotic inclusion thought to be a rickettsia or virus of undetermined taxonomic status was reported in the Ouachita Mountain dusky salamander by McAllister et al. (1995f).
R. Parasites. Few salamanders have been investigated for parasites, but only 41 Ouachita Mountain dusky salamanders produced Chloromyxum salamandrae, Brachycoelium salamandrae, Cylindrtaenia americana, Mesocestiodes sp., Batracholandros magnavulvaris, Desmognathinema nantahalensis, Hedruris pendula, Omeia papillocauda, Ascaridoidea larvae, an acanthocephalan, and a Hannemania sp. mite (McAllister et al., 1995f). Loomis (1956), Means (1974), Winter et al. (1986), and Anthony et al. (1994) also reported the presence of trombiculid mites of the genus Hannemania. Winter et al. (1986) reported cestodes, nematodes, and acanthocephalans.
4. Conservation. Ouachita Mountain dusky salamanders were sampled intensively over their entire geographic range involving about fifty localities in the early 1970s (Means, 1974, 1975b), but there has been no follow-up. Most of the geographic range of the species, however, is on publicly owned lands such as the Ouachita National Forest, part of the Ozark National Forest, Hot Springs National Park, and several state parks in both Arkansas and Oklahoma. The most important conservation measures are to insure that the ecological integrity of the mountain brook habitats of the species are maintained. Careful attention should be paid to avoiding silvicultural practices, such as clearcutting, that would increase sedimentation or alter the hydrology of mountain brook watersheds or deliver pesticides, herbicides, or fertilizers to the aquatic habitat. Impacts of the fish bait industry should be assessed, including whether populations can recover from different levels of harvesting and, particularly, whether local gene pools are being altered by the artificial movement of animals across drainages and among mountain masses. This latter is important because Karlin et al. (1993) showed that populations on different mountain masses were genetically distinct, indicating a high degree of local adaptation. Means (1975b) verified this through morphological analyses.
1D. Bruce Means
Literature references for Amphibian Declines: The Conservation Status of United States Species, edited by Michael Lannoo, are here.
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