{{Short description|Species of amphibian}} {{Speciesbox | image = Texas_blind_salamander.jpg | status = CR | status_system = IUCN3.1 | status_ref = <ref name="iucn">{{cite iucn |author=IUCN SSC Amphibian Specialist Group. |year=2023 |title=''Eurycea rathbuni'' |article-number=e.T39262A118975720}}</ref> | status2=LE | status2_system=ESA | status2_ref=<ref>{{cite web|url=https://ecos.fws.gov/ecp/species/D001|title=Texas blind salamander (''Eurycea rathbuni'')|website=Environmental Conservation Online System|publisher=U.S. Fish & Wildlife Service|access-date=27 April 2023}}</ref><ref>{{Federal Register|32|4001}}</ref> | genus = Eurycea | species = rathbuni | authority = ([[Leonhard Hess Stejneger|Stejneger]], 1896) | synonyms = {{Species list | Typhlomolge rathbuni | Stejneger, 1896 }} | synonyms_ref = <ref name=Frost/> }}
The '''Texas blind salamander''' ('''''Eurycea rathbuni''''') is a rare and endangered [[cave]]-dwelling [[troglobite]] amphibian native to [[San Marcos, Texas|San Marcos]], Hays County, Texas, specifically the San Marcos Pool of the [[Edwards Aquifer]]. This species resembles the [[olm]], another [[stygofauna]]l salamander from Europe. Its body is less elongated than the olm's, and it has more digits on each limb: four on the front limbs and five on the back, while the olm has three and two respectively.
==Description== The species has a broad, flat snout and head, and vestigial eyes beneath that are covered by skin. This species' vestigial eyes contain an optic nerve, but are less developed than those of other species in the ''Eurycea,'' often lacking important features like lenses and well-defined retinas associated with image-forming vision.<ref>{{cite journal |last1=Tovar |first1=Ruben |last2=Cantu |first2=Valentin |last3=Fremaux |first3=Brian |last4=Gonzalez Jr. |first4=Pedro |last5=Spikes |first5=Amanda |last6=García |first6=Dana |title=Comparative development and ocular histology between epigean and subterranean salamanders (Eurycea) from central Texas |journal=PeerJ |date=2021 |volume=9 |article-number=e11840 |doi=10.7717/peerj.11840 |doi-access=free |pmid=34395082 |pmc=8325428 }}</ref> Similar to other cave-dwelling salamanders, this species has numerous neuromasts in their [[lateral line]] that detect mechanical stimuli in the environment.<ref name=":0">{{cite journal |last1=Tovar |first1=Ruben |last2=Dobbins |first2=Brittany |last3=Hartman |first3=Nicholas |last4=Leelani |first4=Sheena |last5=Devitt |first5=Thomas |last6=Garcia |first6=Dana |last7=Gignac |first7=Paul |last8=Cannatella |first8=David |last9=Hillis |first9=David |title=Parallel sensory compensation following independent subterranean colonization by groundwater salamanders (Eurycea) |journal=PNAS |date=June 3, 2025 |volume=122 |issue=23 |article-number=e2504850122 |doi=10.1073/pnas.2504850122 |pmid=40460121 |pmc=12168003 |bibcode=2025PNAS..12204850T }}</ref> Many of these neuromasts express the [[PAX6]] protein, which is often expressed during eye development of other salamander species.<ref>{{cite journal |last1=Dobbins |first1=Brittany |last2=Tovar |first2=Ruben |last3=Oddo |first3=Braden |last4=Teague |first4=Christian |last5=Sindhi |first5=Nisa |last6=Devitt |first6=Thomas |last7=Hillis |first7=David |last8=García |first8=Dana |title=PAX6 protein in neuromasts of the lateral line system of salamanders (Eurycea) |journal=PLOS ONE |date=2024 |volume=19 |issue=8 |article-number=e0293163 |doi=10.1371/journal.pone.0293163 |doi-access=free |pmid=39213295 |pmc=11364236 }}</ref> These neuromasts are thought to play an important role in navigation and prey detection for this species with reduced visual capacity.<ref name=":0" /> Like other [[Neoteny#In other species|neotenous salamanders]], it has external [[gill]]s for absorbing oxygen from the water. The salamander's mature length is around {{Convert| 13|cm|in|0|abbr=on}}. The forelimbs carry four digits and the hind limbs possess five digits.<ref>{{cite journal |last1=Potter |first1=Floyd E. |last2=Sweet |first2=Samuel S. |name-list-style=amp |title=Generic boundaries in Texas cave salamanders, and a redescription of ''Typhlomolge robusta'' (Amphibia: Plethodontidae) |journal=Copeia |date=10 February 1981 |volume=1981 |issue=1 |page=64 |doi=10.2307/1444041 |jstor=1444041 }}</ref> The species is found to be able to regenerate its tail and limbs if they are lost.<ref>{{cite journal | last1=Vieira | first1=Warren A. | last2=Anderson | first2=Kelsey | last3=Glass Campbell | first3=Lindsay | last4=McCusker | first4=Catherine D. | title=Characterizing the regenerative capacity and growth patterns of the Texas blind salamander (''Eurycea rathbuni'') | journal=Developmental Dynamics | date=2021 | volume=250 | issue=6 | pages=880–895 | doi=10.1002/dvdy.245 | pmid=32885536 | pmc=8454265 }}</ref> Its diet varies by what flows into its cave, and includes [[Palaemonetes antrorum|blind shrimp]] (''Palaemonetes antrorum''), snails, and [[amphipods]].<ref name=hillis>{{cite journal|last1=Hillis|first1=D.M.|last2=Chamberlain|first2=D.A.|last3=Wilcox|first3=T.P.|last4=Chippindale|first4=P.T. |name-list-style=amp |year=2001|title=A new species of subterranean blind salamander (Plethodontidae: Hemidactyliini: ''Eurycea'': ''Typhlomolge'') from Austin, Texas, and a systematic revision of central Texas paedomorphic salamanders|journal=Herpetologica|volume=57|pages=266–280}}</ref><ref name=utexas>{{cite web|url=http://www.herpsoftexas.org/content/texas-blind-salamander|publisher=Herps of Texas|title=Texas Blind Salamander|access-date=2015-09-15|archive-date=2020-06-23|archive-url=https://web.archive.org/web/20200623040045/http://www.herpsoftexas.org/content/texas-blind-salamander}}</ref><ref>{{cite journal|last1=Chippindale|first1=P.T.|first2=A.H.|last2=Price|last3=Wiens|first3=J.J.|last4=Hillis|first4=D.M. |name-list-style=amp |year=2000|title=Phylogenetic relationships of central Texas hemidactyliine plethodontid salamanders, genus ''Eurycea'', and a taxonomic revision of the group|journal=Herpetological Monographs|volume=14|pages=1–80|doi=10.2307/1467045|jstor=1467045}}</ref> It is not known if this salamander has any natural predators, however the stygobitic catfish ''[[Satan eurystomus]]'' also lives in Edwards Aquifer, so is a potential predator.<ref name="Langecker">{{cite journal |last=Langecker |first=Thomas G. |author2=Longley, Glenn |year=1993 |title=Morphological Adaptations of the Texas Blind Catfishes ''Trogloglanis pattersoni'' and ''Satan eurystomus'' (Siluriformes: Ictaluridae) to Their Underground Environment |journal=[[Copeia]] |volume=1993 |issue=4 |pages=976–986 |doi=10.2307/1447075 |jstor=1447075 |bibcode=1993Copei1993..976L }}</ref><ref name="fishbase">{{FishBase|genus=Satan|species=eurystomus|year=2011|month=December}}</ref> However, due to the limited range of that fish, it might not come into contact with the amphibian.<ref name="fishbase" />
==Distribution and habitat== Specimens have been collected at seven localities in the [[Purgatory Creek system]] and along the [[Balcones Fault|San Marcos Fault]] near [[San Marcos, Texas]]. Adults and immature larvae are well-adapted for living in underground streams or deep pools in caves, and many probably inhabit deep recesses that are not accessible to collectors. The deep pools are cool environments nearly constantly staying at {{convert|21|-|22|C}} with a minimal current. It is a unique ground system hundreds of feet below Earth's surface. The first specimens of this species were collected in 1895 from a newly constructed well that drew water from {{convert|58|m|ft}} below the surface.<ref name=hillis/>
==Breeding and courtship== [[File:Eurycea rathbuni FWS 20426.jpg|thumb|A Texas blind salamander]] The time of breeding is poorly documented. [[Emmett Reid Dunn|Dunn]] (1926) noted a specimen maintained in the laboratory laid a few eggs on March 15 and a specimen collected in early fall had the [[spermatheca]] packed with [[spermatozoa]]. Very small juveniles have been found throughout the year, suggesting a seasonal breeding pattern.
[[David L. Bechler|Bechler]] (1988) observed one complete and two partial courtship bouts in captive specimens in which the female initiated courtship and the male remained passive initially. Courtship begins when the female approaches the male and rubs her chin on his [[Dorsum (anatomy)|dorsum]]. The female may also rub her [[cloaca]] on nearby rocks while rocking to and fro. If the male does not respond, the female may nip the male along the sides or engage in kicking behavior in which gravel is scratched with the hind limbs. The female eventually straddles the tail of the male and rubs her snout above the tail base. The male responds by arching his pelvic region and fanning his tail between her legs.
The female then rubs her snout more rapidly over the base of the tail. The male may lead the female forward and repeat the same cycle while slowly vibrating the anterior third of the tail. The male eventually bends the body laterally and moves the tail laterally at a right angle to the body while the female continues rubbing the base of the tail. The male then leads the female forward, bends his body into an S-shaped pattern, and deposits a spermatophore on the substrate. He next leads the female forward with the tail extended laterally until she picks up the spermatophore cap with her cloacal lips. The spermatophore consists of a crescent-shaped white sperm cap over a clear, gelatinous base that is about four times longer than it is wide.<ref>{{cite journal |last=Bechler|first=D.L.|year=1988|title=Courtship behavior and spermatophore deposition by the subterranean salamander, ''Typhlomolge rathbuni'' (Caudata, Plethodontidae)|journal=Southwestern Naturalist |volume=33|issue=1|pages=124–126|doi=10.2307/3672107|jstor=3672107 |bibcode=1988SWNat..33..124B }}</ref> The species is found to have a delayed reproductive maturity and low reproductive output, with females found to produce 5 small egg clutches on average per year.<ref>{{cite journal | last1=Glass Campbell | first1=Lindsay | last2=Anderson | first2=Kelsey A. | last3=Marcec-Greaves | first3=Ruth | title=Topical application of hormone gonadotropin-releasing hormone (GNRH-A) stimulates reproduction in the endangered Texas blind salamander (''Eurycea rathbuni'') | journal=Conservation Science and Practice | date=2022 | volume=4 | issue=3 | article-number=e609 | doi=10.1111/csp2.609 | bibcode=2022ConSP...4E.609G | doi-access=free }}</ref>
==Conservation== Populations of Texas blind salamander are sensitive to harsh changes in their environment. Continuous pumping of groundwater for commercial or domestic purposes leaves the salamanders vulnerable to predators and can eventually lead to their extinction. The Edwards Aquifer is becoming polluted from stormwater runoff and chemical spills.<ref>{{Cite report |url=https://pubs.usgs.gov/publication/wri004149 |title=Vulnerability of ground water to contamination, Edwards Aquifer recharge zone, Bexar County, Texas, 1998 |last=Clark |first=Allan K. |date=2000 |publisher=U.S. Geological Survey |issue=2000-4149 |doi=10.3133/wri004149 |language=en}}</ref> Potential drought is also a primary concern.<ref name=":1">{{Cite web |date=2022-08-05 |title=Texas Blind Salamander |url=https://storymaps.arcgis.com/stories/0308010162764eb19ba36b0c87ce4258 |access-date=2026-04-28 |website=ArcGIS StoryMaps |language=en-us}}</ref> Long-term groundwater availability is being monitored using the flow of the [[San Marcos River]] as a surrogate measure.<ref>{{cite web|url=https://ecos.fws.gov/docs/recovery_plan/Final%20RP%20Amendment_San%20Marcos%20and%20Comal%20Springs_508%20Compliant.pdf|title=Recovery Plan Amendments for Eleven Southwest Species|date=6 December 2019|access-date=27 April 2023|publisher=U.S. Fish and Wildlife Service Southwest Region|location=Albuquerque, New Mexico}}</ref>
The salamanders were listed as an endangered species on March 11th, 1967, and their population status continues to be unstable. Recovery plans are currently underway to help save the species. The Edwards Aquifer Habitat Conservation Plan (EAHCP) is a program designed to help these organisms thrive. The EAHCP is taking action by preserving, restoring, and monitoring water sources.<ref name=":1" />
Other efforts to stabilize this population are public education on the effects of overconsumption of water and pollution. Overconsumption of water and pollution causes decline in habitual environments for species like the Texas blind salamander.<ref>{{Cite web |date=2018-05-21 |title=Save Our Salamanders |url=https://www.austinmonthly.com/save-our-salamanders/ |access-date=2026-05-20 |website=Austin Monthly Magazine |language=en-US}}</ref>
==See also==
* [[Axolotl]] * [[Blanco blind salamander]] * [[Olm]]
==References== {{Reflist|refs= <ref name=Frost>{{cite web |url=https://amphibiansoftheworld.amnh.org/Amphibia/Caudata/Plethodontidae/Hemidactyliinae/Eurycea/Eurycea-rathbuni |title=''Eurycea rathbuni'' (Stejneger, 1896) |author=Frost, Darrel R. |year=2021 |work=Amphibian Species of the World: An Online Reference. Version 6.1 |publisher=American Museum of Natural History |doi=10.5531/db.vz.0001 |access-date=5 February 2021}}</ref> }}
==External links== *[https://animaldiversity.org/site/accounts/information/Eurycea_rathbuni.html University of Michigan Museum of Zoology]
{{Taxonbar|from=Q1499777}}
[[Category:Eurycea|rathbuni]] [[Category:Cave salamanders]] [[Category:Amphibians of the United States]] [[Category:Endemic fauna of Texas]] [[Category:San Marcos, Texas]] [[Category:Amphibians described in 1896]] [[Category:Taxa named by Leonhard Stejneger]]