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Leptoxis taeniata

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA MOLLUSCA GASTROPODA SORBEOCONCHA PLEUROCERIDAE

Scientific Name: Leptoxis taeniata
Species Authority: (Conrad, 1834)
Common Name(s):
English Painted Rocksnail

Assessment Information [top]

Red List Category & Criteria: Endangered B1ab(i,ii,iii) ver 3.1
Year Published: 2012
Date Assessed: 2011-10-26
Assessor(s): Bogan, A. & Cordeiro, J.
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:
Leptoxis taeniata has been assessed as Endangered due to its restricted range (estimated extent of occurrence of between 100–1,000 km², depending on whether or not discontinuities within the range are eliminated from the calculation), small number of isolated populations (currently known from three locations) and continuing decline in the extent of habitat available to it. It should be noted that the estimated extent of occurrence for the species may fall within the threshold for the Critically Endangered category if following the procedure of discounting discontinuities within the species' range from the calculation, in which case it is only the number of locations which causes the species to fall within the Endangered category. As such, it is possible, due to the potential impacts from continuing threat processes to the species, that it may in future be placed within the Critically Endangered category if declines continue and lead to disappearance of more subpopulations. Severe range reductions have been observed, which are likely to be ongoing unless threats are ameliorated, although there is uncertainty over the time scale of observed declines and how range reductions scale up to population reductions within this species.
History:
1996 Vulnerable
1994 Indeterminate (Groombridge 1994)

Geographic Range [top]

Range Description: This species is endemic to the U.S. state of Alabama. Historically, it had the largest range of any rocksnail in the Mobile River Basin (Goodrich 1922), and was known from the Alabama and Coosa rivers and their tributaries, and also a short distance along the Cahaba River (Burch 1989). It has now disappeared from 90% of its former range (USFWS 2005) and is currently only known from three populations in the lower reaches of three Coosa River tributaries - Choccolocco Creek, Talladega County; Buxahatchee Creek, Shelby County (Bogan and Pierson 1993); and Ohatchee Creek, Calhoun County (Pierson in litt. 1993 from USFWS 2005). This equates to an estimated extent of occurrence of around 1,000 km², although if discontinuities in range are accounted for, this is likely to be reduced to less than 100 km².
Countries:
Native:
United States (Alabama)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: Population estimates are not known for this species, but due to the reduction in its range size of over 90%, it is thought that there has been a severe population decline of  up to 90% (USFWS 2005). However, there is uncertainty about the precise timescale of the decline and whether declines in range caused equal declines in population numbers within this species.
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: This species is found in riverine systems in the fast-flowing currents of riffles and shoals, attached to hard substrates such as cobble or gravel (Goodrich 1922). It is usually found attached to bedrock ledges and boulders and grazes on biofilm (Miriarchi et al. 2004). Mature individuals are fairly inanimate, and it is thought that females glue eggs to nearby stones (Goodrich 1922). It is said to be more tolerant of siltation than other Leptoxis species in the Mobile Basin (Mirarchi et al.2004)
Systems: Freshwater

Use and Trade [top]

Use and Trade: This species is not utilized.

Threats [top]

Major Threat(s): The already very restricted range of this species is under threat from increasing construction of water reservoirs in the area (NatureServe 2009). USFWS (2000) states that as well as potential future threats from land use change and increasing human population density, isolated populations in the Mobile River basin are likely to be vulnerable to random events both from anthropogenic activities (i.e. toxic spills) and natural catastrophic events (i.e. droughts or floods).

Conservation Actions [top]

Conservation Actions: This species has been given a NatureServe Global Heritage Status Rank of G1 - Critically Imperiled (NatureServe 2006).

There are currently no species-specific conservation measures in place for this species. However, a USFWS (2004, 2005) Recovery Plan exists for six Mobile River basin aquatic snails and outlines conservation objectives for six species, including Leptoxis taeniata, in the Mobile River basin. The recovery criteria outlined in the plan include delisting for all six species which will require the confirmation of at least three stable or increasing populations for each species for 10 or more years. Before either reclassification or delisting may be considered, threats to the species will be removed, and plans should be developed and implemented to protect and monitor water and habitat quality in the watersheds where they occur. The Recovery plan also includes conservation actions that are needed for the six species - (1) Protect habitat integrity and water quality. (2) Develop mitigation strategies that give high priority to avoidance and restoration. (3) Promote increased levels of voluntary stewardship to reduce non-point pollution from private land use. (4) Encourage and support community based watershed stewardship planning and action. (5) Develop and implement public education programs and materials defining ecosystem management and stewardship responsibilities. (6) Conduct basic research on endemic species and apply the results of this research to management. (7) Develop and implement technology for maintaining and propagating endemic species in captivity. (8) Reintroduce imperilled aquatic species into restored habitats, as appropriate. (9) Monitor listed species populations. (10) Coordinate ecosystem management actions and species recovery efforts (USFWS 2000). In addition, Mirarchi et al. (2004) suggest that captive breeding and reintroduction should be considered and a survey conducted in order to locate potential reintroduction sites within the Mobile River drainage that can be utilized where necessary.

Citation: Bogan, A. & Cordeiro, J. 2012. Leptoxis taeniata. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 24 July 2014.
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