The Texas blind salamander (Eurycea rathbuni) is a rare and endangered cave-dwelling troglobiteamphibian native to San Marcos, Hays County, Texas, specifically the San Marcos Pool of the Edwards Aquifer. This species resembles the olm, another stygofaunal salamander from Europe. Unlike the olm, this amphibian's body is not as elongated, and also has less reduced digits on its limbs (the olm only has three digits on its front limbs, and two on the back).
The species has a broad, flat, snout and head, and vestigial eyes beneath that are covered by skin. Like other neotenous salamanders, it has external gills for absorbing oxygen from the water. The salamander's mature length is around 13 cm (5 in). The forelimbs carry four digits and the hind limbs possess five digits.[5] The species is found to be able to regenerate its tail and limbs if they are lost.[6] Its diet varies by what flows into its cave, and includes blind shrimp (Palaemonetes antrorum), snails, and amphipods.[7][8][9] It is not known if this salamander has any natural predators, however the stygobitic catfish Satan eurystomus also lives in Edwards Aquifer, so it might be a potential predator.[10][11] However, due to the limited range of that fish, it might not come into contact with the amphibian.[11]
Distribution and habitatedit
Specimens have been collected at seven localities in the Purgatory Creek system and along the San Marcos Fault near San Marcos, Texas. Adults and immature larvae are well-adapted for living in underground streams in caves, and many probably inhabit deep recesses that are not accessible to collectors. Specimens have been taken in deep pools with minimal current and nearly constant 21–22 °C (70–72 °F) temperatures. The first specimens of this species were collected in 1895 from a newly constructed well that drew water from 58 metres (190 ft) below the surface.[7]
Breeding and courtshipedit
A Texas blind salamander
The time of breeding is poorly documented. 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.
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. 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.[12] 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.[13]
Conservationedit
Populations of Texas blind salamander are sensitive to groundwater pollution.[1] They are additionally vulnerable to depletion of groundwater resources,[1] which occurs over time when withdrawals for commercial or domestic purposes exceed aquifer recharge through percolation, etc. Long-term groundwater availability is being monitored using the flow of the San Marcos River as a surrogate measure.[14]: 9
As of 2004, the population trend of the Texas blind salamander is stable, according to the IUCN.[1] A five-year review published in 2021 identified all downlisting criteria as being "partially complete," but warned that current groundwater withdrawal limits do not take into account the likelihood of increasing frequency and intensity of droughts due to climate change.[15]
^Frost, Darrel R. (2021). "Eurycea rathbuni (Stejneger, 1896)". Amphibian Species of the World: An Online Reference. Version 6.1. American Museum of Natural History. doi:10.5531/db.vz.0001. Retrieved 5 February 2021.
^Potter, Floyd E. & Sweet, Samuel S. (10 February 1981). "Generic boundaries in Texas cave salamanders, and a redescription of Typhlomolge robusta (Amphibia: Plethodontidae)". Copeia. 1981 (1): 64. doi:10.2307/1444041. JSTOR 1444041.
^Vieira, Warren A et al. “Characterizing the regenerative capacity and growth patterns of the Texas blind salamander (Eurycea rathbuni).” Developmental dynamics : an official publication of the American Association of Anatomists vol. 250,6 (2021): 880-895. doi:10.1002/dvdy.245
^ abHillis, D.M.; Chamberlain, D.A.; Wilcox, T.P. & Chippindale, P.T. (2001). "A new species of subterranean blind salamander (Plethodontidae: Hemidactyliini: Eurycea: Typhlomolge) from Austin, Texas, and a systematic revision of central Texas paedomorphic salamanders". Herpetologica. 57: 266–280.
^Chippindale, P.T.; Price, A.H.; Wiens, J.J. & Hillis, D.M. (2000). "Phylogenetic relationships of central Texas hemidactyliine plethodontid salamanders, genus Eurycea, and a taxonomic revision of the group". Herpetological Monographs. 14: 1–80. doi:10.2307/1467045. JSTOR 1467045.
^Langecker, Thomas G.; Longley, Glenn (1993). "Morphological Adaptations of the Texas Blind Catfishes Trogloglanis pattersoni and Satan eurystomus (Siluriformes: Ictaluridae) to Their Underground Environment". Copeia. Copeia, Vol. 1993, No. 4. 1993 (4): 976–986. doi:10.2307/1447075. JSTOR 1447075.
^ abFroese, Rainer; Pauly, Daniel (eds.) (2011). "Satan eurystomus" in FishBase. December 2011 version.
^Bechler, D.L. (1988). "Courtship behavior and spermatophore deposition by the subterranean salamander, Typhlomolge rathbuni (Caudata, Plethodontidae)". Southwestern Naturalist. 33 (1): 124–126. doi:10.2307/3672107. JSTOR 3672107.
^Glass Campbell, L., Anderson, K. A., & Marcec-Greaves, R. (2022). Topical application of hormone gonadotropin-releasing hormone (GnRH-A) stimulates reproduction in the endangered Texas blind salamander (Eurycea rathbuni). Conservation Science and Practice, 4( 3), e609. https://doi.org/10.1111/csp2.609
^"Recovery Plan Amendments for Eleven Southwest Species" (PDF). Albuquerque, New Mexico: U.S. Fish and Wildlife Service Southwest Region. 6 December 2019. Retrieved 27 April 2023.
^"Texas Blind Salamander (Typhlomolge rathbuni) 5-Year Review: Summary and Evaluation" (PDF). Austin, Texas: U.S. Fish and Wildlife Service, Austin Ecological Services Field Office. 26 April 2021. Retrieved 27 April 2023.
External linksedit
University of Michigan Museum of Zoology
December 18, 2023
texas, blind, salamander, eurycea, rathbuni, rare, endangered, cave, dwelling, troglobite, amphibian, native, marcos, hays, county, texas, specifically, marcos, pool, edwards, aquifer, this, species, resembles, another, stygofaunal, salamander, from, europe, u. The Texas blind salamander Eurycea rathbuni is a rare and endangered cave dwelling troglobite amphibian native to San Marcos Hays County Texas specifically the San Marcos Pool of the Edwards Aquifer This species resembles the olm another stygofaunal salamander from Europe Unlike the olm this amphibian s body is not as elongated and also has less reduced digits on its limbs the olm only has three digits on its front limbs and two on the back Texas blind salamanderConservation statusCritically Endangered IUCN 3 1 1 Endangered ESA 2 3 Scientific classificationDomain EukaryotaKingdom AnimaliaPhylum ChordataClass AmphibiaOrder UrodelaFamily PlethodontidaeGenus EuryceaSpecies E rathbuniBinomial nameEurycea rathbuni Stejneger 1896 Synonyms 4 Typhlomolge rathbuni Stejneger 1896 Contents 1 Description 2 Distribution and habitat 3 Breeding and courtship 4 Conservation 5 See also 6 References 7 External linksDescription editThe species has a broad flat snout and head and vestigial eyes beneath that are covered by skin Like other neotenous salamanders it has external gills for absorbing oxygen from the water The salamander s mature length is around 13 cm 5 in The forelimbs carry four digits and the hind limbs possess five digits 5 The species is found to be able to regenerate its tail and limbs if they are lost 6 Its diet varies by what flows into its cave and includes blind shrimp Palaemonetes antrorum snails and amphipods 7 8 9 It is not known if this salamander has any natural predators however the stygobitic catfish Satan eurystomus also lives in Edwards Aquifer so it might be a potential predator 10 11 However due to the limited range of that fish it might not come into contact with the amphibian 11 Distribution and habitat editSpecimens have been collected at seven localities in the Purgatory Creek system and along the San Marcos Fault near San Marcos Texas Adults and immature larvae are well adapted for living in underground streams in caves and many probably inhabit deep recesses that are not accessible to collectors Specimens have been taken in deep pools with minimal current and nearly constant 21 22 C 70 72 F temperatures The first specimens of this species were collected in 1895 from a newly constructed well that drew water from 58 metres 190 ft below the surface 7 Breeding and courtship edit nbsp A Texas blind salamanderThe time of breeding is poorly documented 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 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 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 12 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 13 Conservation editPopulations of Texas blind salamander are sensitive to groundwater pollution 1 They are additionally vulnerable to depletion of groundwater resources 1 which occurs over time when withdrawals for commercial or domestic purposes exceed aquifer recharge through percolation etc Long term groundwater availability is being monitored using the flow of the San Marcos River as a surrogate measure 14 9 As of 2004 the population trend of the Texas blind salamander is stable according to the IUCN 1 A five year review published in 2021 identified all downlisting criteria as being partially complete but warned that current groundwater withdrawal limits do not take into account the likelihood of increasing frequency and intensity of droughts due to climate change 15 See also editAxolotl Blanco blind salamander OlmReferences edit a b c d IUCN SSC Amphibian Specialist Group 2023 Eurycea rathbuni IUCN Red List of Threatened Species 2023 e T39262A118975720 Texas blind salamander Eurycea rathbuni Environmental Conservation Online System U S Fish amp Wildlife Service Retrieved 27 April 2023 32 FR 4001 Frost Darrel R 2021 Eurycea rathbuni Stejneger 1896 Amphibian Species of the World An Online Reference Version 6 1 American Museum of Natural History doi 10 5531 db vz 0001 Retrieved 5 February 2021 Potter Floyd E amp Sweet Samuel S 10 February 1981 Generic boundaries in Texas cave salamanders and a redescription of Typhlomolge robusta Amphibia Plethodontidae Copeia 1981 1 64 doi 10 2307 1444041 JSTOR 1444041 Vieira Warren A et al Characterizing the regenerative capacity and growth patterns of the Texas blind salamander Eurycea rathbuni Developmental dynamics an official publication of the American Association of Anatomists vol 250 6 2021 880 895 doi 10 1002 dvdy 245 a b Hillis D M Chamberlain D A Wilcox T P amp Chippindale P T 2001 A new species of subterranean blind salamander Plethodontidae Hemidactyliini Eurycea Typhlomolge from Austin Texas and a systematic revision of central Texas paedomorphic salamanders Herpetologica 57 266 280 Texas Blind Salamander Herps of Texas Chippindale P T Price A H Wiens J J amp Hillis D M 2000 Phylogenetic relationships of central Texas hemidactyliine plethodontid salamanders genus Eurycea and a taxonomic revision of the group Herpetological Monographs 14 1 80 doi 10 2307 1467045 JSTOR 1467045 Langecker Thomas G Longley Glenn 1993 Morphological Adaptations of the Texas Blind Catfishes Trogloglanis pattersoni and Satan eurystomus Siluriformes Ictaluridae to Their Underground Environment Copeia Copeia Vol 1993 No 4 1993 4 976 986 doi 10 2307 1447075 JSTOR 1447075 a b Froese Rainer Pauly Daniel eds 2011 Satan eurystomus in FishBase December 2011 version Bechler D L 1988 Courtship behavior and spermatophore deposition by the subterranean salamander Typhlomolge rathbuni Caudata Plethodontidae Southwestern Naturalist 33 1 124 126 doi 10 2307 3672107 JSTOR 3672107 Glass Campbell L Anderson K A amp Marcec Greaves R 2022 Topical application of hormone gonadotropin releasing hormone GnRH A stimulates reproduction in the endangered Texas blind salamander Eurycea rathbuni Conservation Science and Practice 4 3 e609 https doi org 10 1111 csp2 609 Recovery Plan Amendments for Eleven Southwest Species PDF Albuquerque New Mexico U S Fish and Wildlife Service Southwest Region 6 December 2019 Retrieved 27 April 2023 Texas Blind Salamander Typhlomolge rathbuni 5 Year Review Summary and Evaluation PDF Austin Texas U S Fish and Wildlife Service Austin Ecological Services Field Office 26 April 2021 Retrieved 27 April 2023 External links editUniversity of Michigan Museum of Zoology Retrieved from https en wikipedia org w index php title Texas blind salamander amp oldid 1189537048, 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