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Tryonia brunei

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA MOLLUSCA GASTROPODA LITTORINIMORPHA COCHLIOPIDAE

Scientific Name: Tryonia brunei
Species Authority: Taylor, 1987
Common Name(s):
English Brune Spring Snail, Brune's Tryonia

Assessment Information [top]

Red List Category & Criteria: Critically Endangered B1ab(i,ii,iii) ver 3.1
Year Published: 2012
Date Assessed: 2012-03-05
Assessor(s): Cordeiro, J. & Perez, K.
Reviewer(s): Bohm, M., Collen, B. & Seddon, M.
Contributor(s): Dyer, E., Soulsby, A.-M., Whitton, F., Kasthala, G., McGuinness, S., Milligan, HT, De Silva, R., Herdson, R., Thorley, J., McMillan, K., Collins, A., Offord, S., Duncan, C. & Richman, N.
Justification:
Tryonia brunei has been assessed as Critically Endangered under criterion B1ab(i,ii,iii). This species is only found in one spring/lake (Phantom Lake) which has an extent of occurrence of less than 100 km2 . The lake was impounded and is still undergoing declines in size and quality due to drought and water abstraction. This species was last observed in 1993 (Hershler 2001) when the lake was surveyed, but no specimens were found since then despite two targeted surveys. There is a chance that individuals survive in the marshes at the type locality, so that further surveys are recommended. In the meantime, we flag this species as possibly extinct.
History:
1996 Data Deficient
1994 Indeterminate (Groombridge 1994)

Geographic Range [top]

Range Description: This species is only known from a single spring lake (Phantom Lake, part of the Balmorhea spring system) in Jeff Davis County, Texas, United States of America (Texas Parks and Wildlife Department 2009). The estimated extent of occurrence is less than 100 km2.
Countries:
Possibly extinct:
United States (Texas)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: This species was abundant on firm substratum prior to modification of the habitat (see threat section) (Texas Parks and Wildlife Department 2009). The species was last observed in 1993, and Hershler (2001) found no living specimens. Targeted surveys have been carried out, but there is still a possibility that the snail might survive in non-viable populations in the marshes at the type locality (K. Perez pers. comm. 2012).
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: This species has been collected from a single freshwater spring - Phantom Lake, part of the Balmorhea spring system in Jeff Davis County, Texas (Texas Parks and Wildlife Department 2009).
Systems: Freshwater

Use and Trade [top]

Use and Trade: This species is not utilised.

Threats [top]

Major Threat(s): There has been a significant decline in the freshwater flow from these springs as a result of water withdrawal for irrigation (Young et al. 1993). Water has been diverted for irrigation and urban use for ca. 30 years from this lake (K. Perez pers. comm. 2010).

Phantom Lake contains several species of endangered fish (two federally listed). Serious recent declines (since 1993) have occurred due to drought and water withdrawal. This lake was dammed and diverted in 1946 (Bureau of Reclamation) and turned from a freshwater marsh to an impounded lake. Although the species may still be present, the range is probably contracted since impoundment and habitat modification.

Although a pump has been installed to keep the habitat filled, the long-term status is not secure.

Conservation Actions [top]

Conservation Actions: This species has been given a Global Heritage Status Rank of G1 - Critically Imperiled by NatureServe (2009). There are no species-specific conservation measures in place for this species. This species has not been seen since 1993, despite two targeted surveys to locate the species. Further surveys are recommended to establish whether populations still exist in the marshes at the type locality.

Citation: Cordeiro, J. & Perez, K. 2012. Tryonia brunei. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 01 September 2014.
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