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Elimia variata

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA MOLLUSCA GASTROPODA SORBEOCONCHA PLEUROCERIDAE

Scientific Name: Elimia variata
Species Authority: (I. Lea, 1861)
Common Name(s):
English Squat Elimia
Taxonomic Notes: Elimia showalteri, Elimia variata, and Elimia olivula may only be clinal variants of a single-species (Bogan and Pierson 1993).

Assessment Information [top]

Red List Category & Criteria: Near Threatened ver 3.1
Year Published: 2012
Date Assessed: 2012-03-12
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.
Justification:
Elimia variata has been assessed as Near Threatened. It nearly qualifies as Vulnerable under criterion B, because of a restricted extent of occurrence of less than 250 km2, demonstrable continuing declines (for example in the number of sites occupied), but the number of locations in which it occurs is likely to exceed ten locations. Further taxonomic work is needed on three similar species in order to assess validity at species level or whether these species represent clinal variants. However, this is unlikely to change the listing of this species, as these species are all found in the same stretch of river. The level of decline is unclear but is listed as Endangered in AL and classified as G1Q by NatureServe - critically imperiled with further research the status of this species may change.
History:
1996 Data Deficient
1994 Indeterminate (Groombridge 1994)

Geographic Range [top]

Range Description: Historically, this species was known from the Cahaba River and tributaries in Shelby and Bibb Counties, and in small numbers in the middle Cahaba River in Jefferson County, Alabama (Burch 1989). It was historically reported in Alabama from Peavine, Buck, and Town Creeks, Shelby Co.; Little Cahaba River, Jefferson Co.; and Cahaba River between the mouth of Buck Creek and Lily Shoals, Shelby and Bibb Cos. Recently, it has only been reported from Buck and Shoal Creeks, Bibb Co.; and Cahaba River at Booths Ford, Shelby Co. (Mirarchi et al. 2004). This is approximately a 100 km stretch, with the total number of locations recorded for E. showalteri being 13 and 3 for olivula.

Further work is required to ascertain taxonomic issues, however if clinal variants turned out to be the same species, the range would still remain small as they are all found in the same stretch of river.
Countries:
Native:
United States (Alabama)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: This species occurs in Cahaba River basin tributaries. Goodrich (1934) cites three shoals in the middle Cahaba River, about 20 miles apart, the Little Cahaba River in Bibb Co., Buck Creek and Bishop Creek, and streams in Montevallo, Shelby Co., Alabama. The species was identified at nine sites by Bogan and Pierson (1993). Actual occurrences may not equal the number of sites/locations after closer examination of actual occurrences. Although historically reported in Alabama from Peavine, Buck, and Town Creeks (Shelby Co.), Little Cahaba River (Jefferson Co.), and Cahaba River between mouth of Buck Creek and Lily Shoals (Shelby and Bibb Cos.), it has only recently been reported from Buck and Shoal Creeks (Bibb Co.), and Cahaba River at Booths Ford (Shelby Co.) (Mirarchi et al. 2004).

This species is declining, but the full extent of the decline (possibly somewhere between 10-50%) has not been determined. In Alligator Creek, Huryn et al. (1994) found the species to be locally abundant, making up 95% of biomass in some stream patches (50-591 individuals per m2).
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: This species occurs in moderate to fast current over shoals on cobble, gravel, and bedrock substrata in small to medium streams and the Cahaba River (Mirarchi et al. 2004). This species reaches maturity at 2-3 years and lives up to 6 years old (Huryn et al. 1994).
Systems: Freshwater

Use and Trade [top]

Use and Trade: This species is not utilized.

Threats [top]

Major Threat(s): This species is somewhat tolerant of non-destructive intrusion but declines have been observed. General threats to its habitat include siltation, sedimentation, pollution and any other processes that cover shoals and prevent feeding.

Conservation Actions [top]

Conservation Actions: This species has been assigned a NatureServe Global Heritage Status Rank of G2Q - Imperiled, but with questionable taxonomy that may reduce conservation priority, and a State/Province Status Rank of S1Q - Critically Imperiled, but with questionable taxonomy that may reduce conservation priority (NatureServe 2009). Further work is needed to resolve the taxonomy of the three possibly clinal species. More information is needed on population trends and threats.

Citation: Cordeiro, J. & Perez, K. 2012. Elimia variata. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 02 September 2014.
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