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Pyrgulopsis thompsoni

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA MOLLUSCA GASTROPODA LITTORINIMORPHA HYDROBIIDAE

Scientific Name: Pyrgulopsis thompsoni
Species Authority: Hershler, 1988
Common Name(s):
English Huachuca Springsnail

Assessment Information [top]

Red List Category & Criteria: Near Threatened ver 3.1
Year Published: 2012
Date Assessed: 2012-03-27
Assessor(s): Cordeiro, J.
Reviewer(s): Bohm, M., Seddon, M. & Collen, B.
Contributor(s): Dyer, E., Whitton, F., Soulsby, A.-M., Kasthala, G., McGuinness, S., Milligan, HT, De Silva, R., Herdson, R., Thorley, J., McMillan, K., Collins, A., Offord, S., Duncan, C. & Richman, N.
Justification:
Pyrgulopsis thompsoni has been assessed as Near Threatened. Although the extent of occurrence is less than 5,000 km² and subpopulations appear to be severely fragmented (making unassisted recolonization of sites unlikely if subpopulations went extinct), there is currently no indication of continuing declines in the number of mature individuals, subpopulations, locations or range extent. In fact, additional populations have been discovered, which suggests that the species is much more widespread than originally thought (NatureServe 2009). The species would qualify for Vulnerable under criterion B if a greater knowledge of population data revealed extreme fluctuations or a continuing decline was demonstrated.
History:
2000 Vulnerable
1996 Data Deficient
1994 Indeterminate (Groombridge 1994)

Geographic Range [top]

Range Description: This species is known from springs in the Huachuca Mountains and the San Rafael Valley in Santa Cruz and Conchise, Arizona, USA (Hurt 2004) and Sonora, Mexico (Hershler and Landye 1988). This species occurs at a number of isolated springs within the Santa Cruz and San Pedro River drainages in Arizona (NatureServe 2009). There is potential suitable habitat in surrounding areas that has not yet been surveyed (Hershler and Landye 1988) and the species appears to be more widespread than originally thought (NatureServe 2009). At present, the species' estimated extent of occurrence is likely to be between 450 km² and 5,000 km².
Countries:
Native:
Mexico (Sonora); United States (Arizona)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: This species is locallly abundant (Hershler and Landye 1988). However, subpopulations occur in isolation which makes it unlikely that sites would be recolonized unassistedly if subpopulations went extinct (Arizona Game and Fish Department 2003). This suggests severe fragmentation of the population.
Population Trend: Unknown

Habitat and Ecology [top]

Habitat and Ecology: This species is collected from freshwater springs and ciénagas in marshy areas characterised by plain grassland, oak and pine-oak woodlands, and coniferous forests (Hershler and Landye 1988).
Systems: Freshwater

Use and Trade [top]

Use and Trade: This species is not utilized.

Threats [top]

Major Threat(s): Current threats include loss or degradation of spring and ciénaga habitat due to overgrazing, timber harvest, altered fire regimes, drought, mining, water developments, recreation, and catastrophic fire resulting from human-caused alterations of fire regimes (Arizona Game and Fish Department 2003). However, there is no indication that these threats are causing continuing declines in the numbers of mature individuals, locations, subpopulations, etc. Similarly, there is no information on continuing declines in extent and quality of habitat, although this may in fact be the case. With additional populations having been discovered recently, the species appears to be more widespread than originally thought (NatureServe 2009), which in turn is likely to lower the severity of threats to this species.

Conservation Actions [top]

Conservation Actions: This species has been given a Global Heritage Status Rank of G2 - Imperiled by NatureServe (2009). There are no species-specific conservation measures in place for this species.

Citation: Cordeiro, J. 2012. Pyrgulopsis thompsoni. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 30 October 2014.
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