The one-toed amphuiuma is an eel-like aquatic salamander. The limbs are extremely tiny and there is only a single toe on each (Neill 1964). As with other members of the family Amphiumidae, there is a single gill slit, no external gills, and the eyes are lidless (Petranka 1998). The dorsum and venter are dark grayish or grayish brown and the venter is only slightly lighter than the dorsum (Means 1992; Petranka 1998). The head is conical and the snout is rounded (Means 1992). This species is considerably smaller than the other two species of Amphiuma. Adults reach 22-33 cm total length (Petranka 1998). The tail is about 25% of the total length. Larvae have branched gills which are resorbed quickly after hatching in the lab; larvae have not been found in the wild (Means 1992).
The three species of Amphiuma are similar but can be differentiated based on the number of toes (one, two, or three), coloration, and body size.
Distribution and Habitat
Country distribution from AmphibiaWeb's database: United States
U.S. state distribution from AmphibiaWeb's database: Alabama, Florida, Georgia, Mississippi
The one-toed amphiuma has a restricted range in extreme southwestern Georgia, the Florida panhandle, northwestern peninsular Florida (Gulf Hammock region), and coastal Alabama. Populations are patchy in distribution and most occur in Florida (Means 1992; Petranka 1998). Populations occur in small ponds, creeks, and intermittent streams. Individuals prefer to occupy the thick, organic muck at the bottom of these water bodies, a factor that may be responsible for the relatively recent discovery of this species and the difficulty in finding populations (Neill 1964; Means 1992).
Life History, Abundance, Activity, and Special Behaviors
The biology of A. pholeter is poorly known. Some features are likely similar to other species of Amphiuma (Petranka 1998). Egg laying probably takes place in the summer (June and July). The female coils around the egg mass and hatching occurs in the late summer/early fall (Means 1992).
Diet consists of mud-dwelling invertebrates, including earthworms, sphaeriid clams, arthropod larvae, and beetles. Possible predators include racoons, feral pigs, mud snakes (Farancia), snapping turtles, and two-toed amphiumas. Although they tend to keep to the thick bottom-layer of muck, one-toed amphiumas must come to the surface to breathe. During dry periods and droughts, one-toed amphiumas will stay in burrows at least 12 inches underground (Means 1992).
Trends and Threats
Classified as Rare in Florida due to the restricted geographic range, small number of known populations, and unusual habitat type (Means 1992). The Rare status implies that populations not currently endangered or threatened are at risk due to restricted ranges or patchy distribution, both of which apply to A. pholeter (Moler 1992). The wetland habitat of one-toed amphiumas is at risk due to development and agriculture (Means 1992).
Because of its small size relative to other amphiumas and reduced number of toes, A. pholeter is considered a dwarf species (Neill 1964; Conant and Collins 1991). Amphiuma means and A. tridactylum are genetically similar, while A. pholeter is quite distinct and likely represents an ancient evolutionary lineage (Karlin and Means 1994).
Conant, R. and Collins, J. T. (1991). A Field Guide to Reptiles and Amphibians: Eastern/Central North America. Houghton Mifflin, Boston.
Karlin, A. A., and Means, D. B. (1994). ''Genetic variation in the aquatic salamander genus Amphiuma.'' American Midland Naturalist, 132, 1-9.
Means, D. B. (1992). "One-toed Amphiuma." Rare and Endangered Biota of Florida. Volume 3. Amphibians and Reptiles. Moler, P. E., eds., University Press of Florida, Gainsville, FL., 34-38.
Moler, P. E. (ed.) (1992). Rare and Endangered Biota of Florida. Volume 3. Amphibians and Reptiles. University Press of Florida
Neill, W. T. (1964). "A new species of salamander, Genus Amphiuma, from Florida." Herpetologica, 20, 62-66.
Petranka, J. W. (1998). Salamanders of the United States and Canada. Smithsonian Institution Press, Washington and London.
Written by Meredith J. Mahoney (molge AT yahoo.com), Museum of Vertebrate Zoology, UC Berkeley
First submitted 2000-07-20
Edited by M. J. Mahoney (2001-04-23)
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