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Country distribution from AmphibiaWeb's database: United States
Eurycea tynerensis Moore and Hughes, 1939
Ronald M. Bonett1
1. Historical versus Current Distribution. Oklahoma salamanders (Eurycea tynerensis) were discovered in 1939 by ichthyologists seining in Tyner Creek, Adair County, Oklahoma (Moore and Hughes, 1939). The geographic distribution of Oklahoma salamanders currently is uncertain. They have been considered to range throughout the Springfield Plateau of northwestern Arkansas, northeastern Oklahoma, and southwestern Missouri (Dundee, 1965b; Conant and Collins, 1998; Petranka, 1998). Due to the subterranean tendencies of this neotenic species, the putative distribution described above includes drainage systems and physiographic regions that may potentially harbor populations of Oklahoma salamanders (Dundee, 1965b). The distribution of known localities, however, appears to be considerably smaller than their proposed range. The entire distribution of Oklahoma salamanders is nested within that of the extremely similar gray-bellied salamanders (E. multiplicata griseogaster), which have transforming adults (Petranka, 1998). Multivariate morphological analyses by Tumlison et al. (1990a) attempted to provide a mechanism for discerning Oklahoma salamanders from larval gray-bellied salamanders. However, they examined only specimens of gray-bellied salamanders from populations that are distant (120–220 km) from the known range of Oklahoma salamanders and did not examine specimens of each species from populations in regions of proposed sympatry or parapatry. It is therefore difficult to determine whether their results show true morphological differences between species or simply geographic variation within a single taxon. Furthermore, unpublished data show some populations of Oklahoma salamanders and gray-bellied salamanders to be indistinguishable based on allozymes (R. Wilkinson, personal communication). For this reason, all populations in Missouri formerly considered E. tynerensis are now considered to be E. m. griseogaster (Johnson, 2000). I am currently undertaking a study that includes delineating the species boundaries and revising the taxonomic status of the members of this complex using molecular and morphological data.
2. Historical versus Current Abundance. No extirpations of populations or range extensions in previously uninhabited regions have been reported for Oklahoma salamanders.
3. Life History Features.
A. Breeding. Reproduction is aquatic.
i. Breeding migrations. Natural populations of Oklahoma salamanders currently are thought to include only permanently aquatic, non-transforming individuals (Petranka, 1998). As explained in other sections, Oklahoma salamanders exhibit considerable movement within their aquatic habitat, but the degree of migration for breeding purposes is unknown.
ii. Breeding habitat. Presumably the same as adult habitat.
i. Egg deposition sites. Egg clutches of Oklahoma salamanders have yet to be recovered in the field.
ii. Clutch size. In mid May and mid November, 1–11 eggs were harvested from three gravid females collected in Arkansas (Trauth et al., 1990), and gravid females collected in Oklahoma in late May contained as many as seven eggs measuring 1.8 x 1.5 mm (Moore and Hughes, 1939).
C. Larvae/Metamorphosis. Hatchlings measure from 9–13 mm TL (Dundee, 1965b). Morphological differences between larvae and adults are slight, with larvae having fewer ampullary (electroreceptor) organs and larger tail fins and gills (Moore and Hughes, 1939). Four Oklahoma salamanders were induced to metamorphose (undergoing a loss of gills and tail fin, alterations in the morphology of the skull and eyes, and exhibiting an affinity for terrestriality) when treated with thyroxin (Kezer, 1952).
D. Juvenile Habitat. Probably are the same as for adults, although studies that examine micohabitat usage by Oklahoma salamanders at various life stages have not been conducted.
E. Adult Habitat. Traditionally, Oklahoma salamanders were thought to inhabit only cool, clear, swift streams that contain coarse gravel, where this species hides (Moore and Hughes, 1939; Dundee, 1958). Tumlison et al. (1990c) conducted thorough examinations of surface habitat parameters that are most preferable to Oklahoma salamanders. Abiotically, they found shallow, slowly moving streams containing medium-sized rocks that are only partially embedded to reliably contain Oklahoma salamanders. Oklahoma salamanders also were found to be most abundant in areas where aquatic invertebrate densities are high. However, it is unclear if this biotic factor results from Oklahoma salamanders preferring areas of high prey density or a mutual response of both the aquatic invertebrates and Oklahoma salamanders to water conditions or predator avoidance. Additional observations on the habitat of Oklahoma salamanders reveal that they also occur in small springs and seeps amongst moist leaf-litter over a mud-and-detritus substrate (Tumlison and Cline, 1997).
F. Home Range Size. Unknown.
G. Territories. Unknown.
H. Aestivation/Avoiding Dessication. Dundee (1958) reported drought conditions to cause mass migrations of Oklahoma salamanders to more hospitable subsurface environments. A persistent drought dried Tyner Creek, Adair County, Oklahoma (the type locality for E. tynerensis), from 1951–'55, but excavation of the stream bed revealed water 2.4 m (8 ft) below the surface, where Oklahoma salamanders apparently seek refuge (Dowling, 1956).
I. Seasonal Migrations. The discovery of subterranean isopods (Caecidotea sp.) in the stomachs of two specimens and the location of many individuals in small, isolated springs distant from a main stream course led Tumlison and Cline (1997) to propose that Oklahoma salamanders may be migrating along subterranean corridors to reach resource-rich habitats on the surface. However, high densities of Oklahoma salamanders in rather atypical habitats might also be interpreted as a sequestering of all individuals into the last remaining moist habitats to survive drought conditions.
J. Torpor (Hibernation). Unknown and unstudied.
K. Interspecific Associations/Exclusions. Rudolph (1978) reported that ≤ 4 additional species of plethodontids with stream-dwelling larval stages are sympatric with Oklahoma salamanders. Among those are cave salamanders (E. lucifuga), dark-sided salamanders (E. longicauda melanopleura), gray-bellied salamanders (E. m. griseogaster), and grotto salamanders (Typhlotriton spelaeus). Rudolph (1978) found substantial differences between Oklahoma salamanders and other species in their ability to survive flood conditions, probably by seeking refuge within the gravel. He also noted that Oklahoma salamanders were the only species that are able to coexist with grotto salamanders at the heads of springs.
L. Age/Size at Reproductive Maturity. Oklahoma salamanders reach sexual maturity in 2–3 yr (Dundee, 1958) at approximately 26 mm SVL (Dundee, 1965b). Sexual size dimorphism has not been noted.
M. Longevity. Unknown.
N. Feeding Behavior. A wide array of prey items has been identified from the digestive tracts of Oklahoma salamanders, including dipterans, ephemeropterans, plecopterans, coleopterans, trichopterans, hymenopterans, thysanopterans, odonates, ostracods, isopods, amphipods, decapods, hydracarians, and pulmonates (Tumlison et al., 1990b). In addition, pulmonates, copepods, and homopterans were identified from the feces of Oklahoma salamanders (Rudolph, 1978).
Specimens used in an attempt to observe feeding postures of Oklahoma salamanders (Dodd, 1980) were later re-identified as grotto salamanders (Dodd, 1982).
O. Predators. Oklahoma salamander larvae were consumed by fishes, including banded sculpins (Cottus carolinae), black bullheads (Ameiurus melas), and green sunfish (Lepomis cyanellus) under laboratory conditions (Rudolph, 1978), but predation by fish in the wild has not been reported. Of the Oklahoma salamanders collected by Tumlison et al. (1990c), 22% had autotomized tails, which was suggested might be a result of predation by crayfish that occupy the same rocky substrate.
P. Anti-Predator Mechanisms. In laboratory trials, fish predation was substantially less on larval Oklahoma salamanders than on grotto salamander, cave salamander, and long-tailed salamander larvae. This was attributed to the tendency of Oklahoma salamanders to seek refuge beneath the gravel substrate (Rudolph, 1978). In additional trials using leafy substrates, Oklahoma salamanders still evaded fish predation best, but there were more individuals consumed than in the trials on gravel substrate (Rudolph, 1978). Tumlison et al. (1990c) hypothesized that the shallow water preference of Oklahoma salamanders may reflect the exclusion of some fish (i.e., Cottus sp.) from such shallow depths.
Q. Diseases. Have not been reported or systematically studied.
R. Parasites. Two parasites have been described from Oklahoma salamanders: an echinorynchid worm, Acanthocephalus van cleavi (Hughes and Moore, 1943a), and a polystomatid fluke, Sphyranura euryceae (Hughes and Moore, 1943b).
4. Conservation. Eurycea tynerensis, once listed as Rare on Missouri’s Rare and Endangered Species List (Johnson, 1987), is no longer recognized as a valid taxon in Missouri (Johnson, 2000). The name E. tynerensis is still used in Oklahoma, but it is provided with no special protected status there. In Arkansas, E. tynerensis is considered to be a Species of Special Concern, and collecting permit requests are closely monitored (K. Irwin, personal communication).
Being permanently aquatic leaves this species particularly vulnerable to alterations in water quality and pollutants. Much needed studies using molecular techniques to determine the differences between E. tynerensis and E. multiplicata, and to define their distributions, are currently in progress. The seasonal movements of Oklahoma salamanders, in particular their tendency to follow stream levels to subsurface habitats, may complicate monitoring studies of this species (Dowling, 1956). An understanding of the subterranean abundance and activity of Oklahoma salamanders will provide valuable insights into their status and conservation requirements.
1Ronald M. Bonett
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 May 2017.
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