Texas Blind Salamander
Covered Species Information
Authored by Connor Helsel
The Texas blind salamander (Eurycea rathbuni) exists exclusively in the Edwards Aquifer of Central Texas. The first individuals of this species were collected in 1895 from the artesian well of the old Federal Fish Hatchery (currently Texas State University campus) in San Marcos, TX (Longley, 1978). Since then, certain localized Texas blind salamander populations have been lost in areas that it was known to inhabit (Chippindale & Fries, 2005; Longley, 1978).
The species’ continued survival is threatened by over pumping of the Edwards Aquifer and reductions in water quality as a result of human population growth in the San Antonio-New Braunfels metropolitan area where a significant amount of water is drawn from the Edwards Aquifer (Campbell & Crow, 2017; Krejca & Gluesenkamp, 2007). To combat over-extraction of the aquifer, the EAHCP has established programs to protect springflow in times of drought, such as the Aquifer Storage and Recovery program and the Voluntary Irrigation Suspension Program Option.
Texas blind salamander
Endangered Species Act status
Reaches a size of 90-135 mm total length (Chippindale & Fries, 2005).
Physical description and Life History
The Texas blind salamander is a troglobitic (cave dwelling) species of the Plethodontidae family (lungless salamanders). It is neotenic, meaning the blind salamander retains traits from early life stages, such as gills and tail fins, throughout its entire life cycle (Campbell & Crow, 2017). Texas blind salamanders are smooth with little skin pigment, red external gills, a broad head, and long and slender limbs. Adapting to its dark cave environment, the Texas blind salamander is blind, lacking eyes, only having two dark spots beneath the skin (Edwards Aquifer Recovery Implementation Program [EARIP], 2012).
There is little difference in physical appearance between sexes and gender identification can be difficult when candling is not possible, until females become visible gravid (egg carrying) (Campbell & Crow, 2017; Gillette & Peterson 2001). Gravid females of this species have been found to lay clutches of fertilized eggs with hatching times around 30 days depending on water temperature (Campbell & Crow, 2017). Little is known of their behavior and reproduction in the wild, given the species’ subterranean dwelling.
The Texas blind salamanders are found in caverns of the San Marcos Pool of the Edwards Aquifer, in an area as small as 25.9 mi² (EARIP, 2012; U.S. Fish and Wildlife Service, 1996).
Habitat and Diet
The Texas blind salamander requires a supply of springwater with a constant temperature of 21-22º C and a dissolved oxygen range of 4-8 mg/L (Campbell & Crow, 2017).
The Texas blind salamander is the top predator of its subterranean habitat (Longley, 1978). These salamanders hunt their prey by sensing disturbances in water pressure waves of the still underground waters (Campbell & Crow, 2017). Diet consists of subterranean invertebrates, such as amphipods, snails, and cave shrimp (Chippindale & Fries, 2005).
Bechler, D. L. (1988). Courtship Behavior and Spermatophore Deposition by the Subterranean Salamander, Typhlomolge rathbuni (Caudata, Plethodontidae). The Southwestern Naturalist, 33(1), 124. https://doi.org/10.2307/3672107
Campbell, L., & Crow, J. (2017). Captive Propagation Eurycea sp. 41. http://edwards.stagingsoftware.com/wp-content/uploads/2020/04/2017-Refugia-Appendices.pdf
Chippindale, P. T., & Fries, J. N. (2005). Eurycea nana San Marcos Salamander. In M. J. Lannoo, Amphibian Declines: The Conservation Status of United States Species (pp. 755–756). University of California Press.
Chippindale, P. T., Price, A. H., Wiens, J. J., & Hillis, D. M. (2000). Phylogenetic Relationships and Systematic Revision of Central Texas Hemidactyliine Plethodontid Salamanders. Herpetological Monographs, 14, 1. https://doi.org/10.2307/1467045
Edwards Aquifer Recovery Implementation Program. (2012). Habitat Conservation Plan (p. 414). https://www.edwardsaquifer.net/pdf/Final_HCP.pdf
Gillette, J. R., & Peterson, M. G. (2001). The benefits of transparency: candling as a simple method for determining sex in red-backed salamanders (Plethodon cinereus). Herpetological Review, 32(4), 233.
Krejca, J. K., & Gluesenkamp, A. (2007). Mark-Recapture Study of Eurycea Rathbuni at Two Sites in San Marcos, Texas. Report prepared for Texas Parks and Wildlife Department.
Longley, G. (1978). Status of Typhlomolge (=Eurycea) rathbuni, the Texas blind salamander. U.S. Fish and Wildlife Service Endangered Species Report 2.
National Academies of Sciences, Engineering, and Medicine. 2018. Review of the Edwards Aquifer Habitat Conservation Plan: Report 3. Washington, DC: The National Academies Press. https://doi.org/10.17226/25200
U.S. Fish and Wildlife Service. 1996. San Marcos/Comal (Revised) Recovery Plan. Albuquerque, New Mexico. pp. x + 93 with 28 pages of appendices