Dark-sided Salamander, Brownback Salamander, Jefferson County Salamander
© 2011 Todd Pierson (1 of 1)
Country distribution from AmphibiaWeb's database: United States
Eurycea aquatica (Rose and Bush, 1963)
Kenneth H. Kozak1
1. Historical versus Current Distribution. Dark-sided salamanders (Eurycea aquatica) are known from small springs in the Ridge and Valley Physiographic Province of Alabama (Jefferson, Shelby, and Saint Clair counties; Rose and Bush, 1963; Jones, 1980) and northwestern Georgia (Catoosa, Chattooga, Floyd, Gordon, Murray, Walker, and Whitfield counties; Rose and Bush, 1963; Jones, 1980). They appear to be absent south of the Coosa River despite the availability of suitable spring habitats (Jones, 1980). Ashton (1966) reported specimens matching the description of dark-sided salamanders from Davidson County, Tennessee, in the Interior Low Plateaus Physiographic Province.
The species status of E. aquatica is controversial. Mount (1975) examined dark-sided salamanders from Alabama and found many individuals intermediate in morphology between southern two-lined salamanders (E. cirrigera) and dark-sided salamanders; he therefore considered these two taxa conspecific. Similarly, Jones (1980) conducted a comprehensive morphological study of the E. bislineata complex in the Ridge and Valley Province of Alabama and Georgia. At many of the examined localities, "intermediates" between southern two-lined salamanders and dark-sided salamanders were found, which Jones (1980) also interpreted as evidence of hybridization. Both Mount (1975) and Jones (1980) considered dark-sided salamanders to represent a "spring ecotype" of southern two-lined salamanders rather than a distinct species. Jacobs (1987) studied allozyme variation in the E. bislineata complex and found E. aquatica from the type locality in Jefferson County, Alabama, to be similar to Junaluska salamanders (E. junaluska) and some populations of E. cirrigera. Similarly, Wallace (1975) found that individuals possessing morphological characters of E. aquatica and E. cirrigera were genetically indistinguishable.
Redmond and Scott (1996) follow Wallace (1975) and place E. aquatica in Tennessee in synonomy with E. cirrigera. However, the status of E. aquatica in Alabama and Georgia remains controversial. Petranka (1998) considers E. aquatica to be synonymous with E. cirrigera, but Sever (1989) states that "the formal decision on the status of E. aquatica must await the comprehensive study of the species in Alabama and neighboring areas called for by Mount (1975) and Jones (1980)." Phylogeographic analyses of mtDNA variation indicate that populations of E. aquatica from the Ridge and Valley Province in Alabama form a monophyletic group that is divergent from any recognized species in the E. bislineata complex (Kozak and Larson, in preparation). This result corroborates Jacob's (1987) allozyme data indicating that E. aquatica from the type locality are genetically distinct from populations of E. cirrigera in Alabama, Georgia, and Tennessee. Thus, E. aquatica from the Ridge and Valley Province of Alabama should be considered an evolutionary unique lineage that warrants conservation (Moritz, 1999).
2. Historical versus Current Abundance. Unknown. Rose (1971) states: "The springs in the area of the type locality of Eurycea aquatica are very small, and transformed animals in this area are nonexistent. Wholesale destruction of the springs was hastened by the discovery of endemic fish in the area and undisciplined herpetological collecting."
3. Life History Features. Many aspects of the life history of dark-sided salamanders have not been described. Refer to the Eurycea cirrigera (Pauley, this volume) and E. bislineata (northern two-lined salamanders; Sever, this volume) accounts for information that can be used provisionally until data on dark-sided salamanders can be collected.
i. Breeding migrations. Unlikely. During wet periods and at higher altitudes, adults may wander far from breeding areas in springs, seeps, and streams. Dry conditions, however, will cause these animals to return to aquatic habitats. Eggs are laid in water, and larvae are aquatic, so females will congregate at appropriate nesting sites (see species accounts for Eurycea cirrigera; Pauley, this volume; and E. bislineata; Sever, this volume).
ii. Breeding habitat. Springs and small woodland streams are the most likely nesting sites (Rose and Bush, 1963).
i. Egg deposition sites. Eggs are likely deposited on the undersides of rocks and logs in flowing water, and females brood (see Pauley, this volume; Sever, this volume).
ii. Clutch sizes. The average clutch size in the vicinity of the type locality is 80 (range 60–96; Rose and Bush, 1963). Clutch sizes for northern two-lined salamanders and southern two-lined salamanders average from 20–50 (see Pauley, this volume; Sever, this volume), suggesting the reproductive potential of dark-sided salamanders is high relative to other species in the E. bislineata complex.
C. Larvae/Metamorphosis. Larvae are aquatic.
i. Length of larval stage. There is typically a bimodal distribution of larval SVLs, suggesting that the larval stage lasts 2 yr. The largest larvae are 30 mm SVL (Rose and Bush, 1963).
ii. Larval requirements.
a. Food. Larvae are carnivorous and likely eat a variety of insect and other invertebrate prey. Major prey items include isopods, amphipods, midges, dipteran pupae, stonefly nymphs, and chironomid larvae, as well as copepods, cladocerans, and other zooplankton (Caldwell and Houtcooper, 1973; Burton, 1976; Petranka, 1984b).
b. Cover. As with larvae of southern two-lined salamanders and northern two-lined salamanders, dark-sided salamander larvae generally are nocturnal, and likely prefer the bottoms of shallow, quiet pools that form below riffle areas in rocky streams. They may also be found by searching among the rocks and logs in riffles (see Pauley, this volume; Sever, this volume). At the type locality, larval dark-sided salamanders were found hidden on the bottom of the spring among aquatic vegetation (Rose and Bush, 1963).
iii. Larval polymorphisms. Not known to occur.
iv. Features of metamorphosis. There may be a large amount of variation in the time to metamorphosis, although this must be examined.
v. Post-metamorphic migrations. Unlikely.
vi. Neoteny. In the vicinity of the type locality seven larvae longer than 28 mm with large black testes and coiled vasa deferentia were collected. Likewise, 20 larvae > 28 mm with enlarged yolked ova have been collected from this same region. All these larvae also had adult pigmentation patterns (Rose and Bush, 1963).
D. Juvenile Habitat. Unknown, but likely the same as adults.
E. Adult Habitat. The primary habitat of dark-sided salamanders appear to be springs and streams in wooded areas (Rose and Bush, 1963). In the Ridge and Valley Province of Alabama and Georgia, populations are associated with limestone and dolomitic springs (Jones, 1980).
F. Home Range Size. Unknown.
G. Territories. Unknown.
H. Aestivation/Avoiding Dessication. Aestivation is unknown.
I. Seasonal Migrations. Unknown.
J. Torpor (Hibernation). Unknown.
K. Interspecific Associations/Exclusions. Dark-sided salamanders occur syntopically with southern dusky salamanders, long-tailed salamanders (E. longicauda), spring salamanders (Gyrinophilus porphyriticus), red salamanders (Pseudotriton ruber), and northern dusky salamanders (Desmognathus fuscus). Detailed studies on the ecological interactions between dark-sided salamanders and sympatric species have not been determined.
L. Age/Size at Reproductive Maturity. Attained during or shortly after metamorphosis (Rose and Bush, 1963).
M. Longevity. Unknown.
N. Feeding Behavior. Dark-sided salamanders likely feed on a wide range of invertebrates. Potential prey include annelids, snails, arachnids, and isopods, and insects such as beetles, bugs, roaches, springtails, dipterans, and hymenopterans (Hamilton, 1932; Burton, 1976).
O. Predators. Unknown.
P. Anti-Predator Mechanisms. Closely related species in the E. bislineata complex assume a defensive posture when attacked by small mammals and birds, and they may be unpalatable (Dowdy and Brodie, 1977). Tail autotomy is also known in this group (Whiteman and Wissinger, 1991).
Q. Diseases. Unknown.
R. Parasites. Unknown.
4. Conservation. There appear to be at least three threats to dark-sided salamanders: (1) host springs are small, (2) endemic fish have drawn much attention, and (3) herpetological collections have been undisciplined.
1Kenneth H. Kozak
2Michael J. Lannoo
Literature references for Amphibian Declines: The Conservation Status of United States Species, edited by Michael Lannoo, are here.
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Citation: AmphibiaWeb. 2017. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 25 Sep 2017.
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