Comprehensive DescriptionRead full entry
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.
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).