Marstonia castor


Taxonomy [top]

Kingdom Phylum Class Order Family

Scientific Name: Marstonia castor
Species Authority: F.G. Thompson, 1977
Common Name(s):
English Beaverpond Marstonia, Beaver Pond Marstonia
Pyrgulopsis castor (Thompson, 1977)
Taxonomic Notes: The genus Marstonia formerly was relegated to synonymy with Pyrgulopsis by Hershler and Thompson (1987). But Thompson and Hershler (2002) later re-evaluated eastern North American species assigned to Pyrgulopsis and recognized them as distinct species of the genus Marstonia (J. Cordeiro pers. comm. 2010).

Assessment Information [top]

Red List Category & Criteria: Critically Endangered B1ab(v) ver 3.1
Year Published: 2012
Date Assessed: 2012-04-11
Assessor(s): Cordeiro, J. & Perez, K.
Reviewer(s): Bohm, M., Seddon, M. & Collen, B.
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.
Marstonia castor has been assessed as Critically Endangerd under criterion B1. It is only known from one locality and has an extent of occurrence of less than 4 km2. The species is likely to be in decline in terms of number of mature individuals, since surveys in 1995 of 22 sites (including the type locality) were unsuccessful in finding this species, compared to over 50 collected specimens in 1973. Further surveys are recommended to corroborate these declines, and also to establish their causes, as there is currently no information available on what processes might be threatening this species.
1996 Data Deficient
1994 Indeterminate (Groombridge 1994)

Geographic Range [top]

Range Description: This species has only ever been known from the type locality, a creek in Crisp Co., Georgia (Burch 1989, Hershler 1994, Watson 2000). The extent of occurrence is 4 km2.
United States (Georgia)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: This species is only known from the type locality, Cedar Creek (which empties into the east side of Lake Blackshear reservoir) on the Flint River in Crisp Co., Georgia (Hershler 1994). Surveys in 1995 of 22 sites (including the type locality) on tributaries of the Flint River between Andersonville and Albany, Georgia, were unsuccessful in finding this species (Watson 2000), compared to over 50 collected specimens in 1973. This suggests a population decline.
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: This species is found only in quiet, clear, cool freshwater on aquatic plants in a single creek (O'Connor 1975).
Systems: Freshwater

Use and Trade [top]

Use and Trade: This species is not utilized.

Threats [top]

Major Threat(s): Threats impacting the global population of this species are unknown, so if suspected declines are corroborated, it is unclear what is causing these.

Conservation Actions [top]

Conservation Actions: This species has been assigned a NatureServe Global Heritage Status of G1 - Critically Imperiled, due to its extremely limited distribution (NatureServe 2009). There are no conservation measures in place for this species. Further research is needed in order to ascertain the population trends and the impact of threats to this species.

Citation: Cordeiro, J. & Perez, K. 2012. Marstonia castor. The IUCN Red List of Threatened Species. Version 2014.3. <>. Downloaded on 28 March 2015.
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