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Background Regeneration of complex patterned structures is well described amongst, although limited to a small sampling of, amphibians. This limitation impedes our understanding of the full range of regenerative competencies within this class of vertebrates, according to phylogeny, developmental life stage and age. To broaden the phylogenetic breath of this research, we characterized the regenerative capacity of the Texas blind salamander (Eurycea rathbuni), a protected salamander native to the Edwards Aquifer of San Marcos, Texas and colonized by the San Marcos Aquatic Resource Center. As field observations suggested regenerative abilities in this population, the forelimb stump of a live captured female was amputated in the hopes of restoring the structure, and thus locomotion in the animal. Tails were clipped from two males to additionally document tail regeneration. Results We show that the Texas blind salamander exhibits robust limb and tail regeneration, like all other studied Plethodontidae. Regeneration in this species is associated with wound epithelium formation, blastema formation and subsequent patterning and differentiation of the regenerate. Conclusions The study has shown that the Texas blind salamander is a valuable model to study regenerative processes, and that therapeutic surgeries offer a valuable means to help maintain and conserve this vulnerable species. This article is protected by copyright. All rights reserved.

Association patterns and social interactions of salamanders vary given habitat heterogeneity and behavioural characteristics. Cave ecosystems are generally food limited and encountering mates may be rare. Little is known about the mode of social interactions and preferences in cave-adapted salamanders. We examined social interactions of the caveadapted, federally endangered, Texas blind salamander, Eurycea rathbuni, by examining sex-specific association patterns. We predicted that non-visual (chemical) cues would be an important mode of communication. We found no difference in association patterns between the sexes when presented with a single conspecific and no aggregative behaviours were detected. Interestingly, when given a simultaneous choice between a male or female, females preferred to associate with male conspecifics while males showed no clear preference. The results suggest that females of E. rathbuni use chemical cues to either seek males or avoid females and provide valuable insight into the little known social behaviour of this species and possibly other similar species.

Salamanders of the genus Eurycea (Plethodontidae: Plethodontinae: Hemidactyliini) are widely distributed in eastern and south-central North America, reaching their westernmost limits in the Interior Highlands of the United States and the Edwards Plateau region of central Texas. Populations of Eurycea in the latter two areas probably represent relicts of previously more widely distributed taxa that became restricted to islands of moist or aquatic habitat during periods of drying (see Chippindale, 1995; Chippindale et al., in review; Potter and Sweet, 1981; Sweet, 1977b, 1978a, 1982; and Wake, 1966, for discussions of the biogeographic history of the group). This is particularly evident in central Texas, where populations of Eurycea are widely scattered and invariably are associated with spring outflows or caves that contain water. Nearly all central Texas populations of Eurycea are obligately aquatic and perennibranchiate, retaining gills and other larval features throughout their lives. Many cave populations are known, most of which probably originated from surface dwellers that moved underground due to disappearance of surface springs or stream capture (Sweet, 1978a,Sweet 1984). Cave-dwellers in the group exhibit a spectrum of cave-associated morphological features that include varying degrees of skin pigment and eye reduction, and in some cases osteological modifications such as broadening and flattening of the skull, limb elongation, and reduction in numbers of trunk vertebrae. The two species formerly assigned to the genus Typhlomolge represent the extreme in cave-associated morphological divergence. I will refer to these species as Eurycea rathbuni and E. robusta for the remainder of this chapter, and offer a more detailed explanation below.