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Cyprogenia aberti

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA MOLLUSCA BIVALVIA UNIONOIDA UNIONIDAE

Scientific Name: Cyprogenia aberti
Species Authority: Conrad, 1850
Common Name(s):
English Western Fanshell, Edible Naiad, Edible Pearly Mussel, Western Fan-shell, Western Fanshell Mussel
Taxonomic Notes: A current taxonomic challenge to Cyprogenia aberti was brought about by a phylogenetic analysis indicating C. aberti is not a monophyletic group and may comprise 2 and possibly 5 distinct taxa, one of which includes the federally endangered Cyprogenia stegaria (Serb, 2003; 2006). In Serb's analysis, there are 2 major clades of fanshells, A and B. Cyprogenia from the Black River (White River system) are closely related to C. stegaria from the Clinch River in Tennessee, and form one clade within clade A. Cyprogenia from the upper Arkansas system also form one well-supported clade within clade A.  A portion of the Cyprogenia from the Ouachita and St. Francis River systems form the final clade in clade A.  Cyprogenia from the St. Francis, White and Ouachita River systems form the two clades within Clade B.  Serb (2006) surmises that the best fit scenario to the phylogenetic results obtained is that C. aberti contains cryptic biological diversity including distinct lineages (species) of unionids on separate evolutionary paths including two distinct non-interbreeding entities occurring sympatrically in the Ouachita System with reproductive barriers.  She does not go so far as to separate the entities into distinct species yet but suggests other independent data (such as life history traits) are needed to support designation of multiple species.  Based on morphology, the above work by Serb, and differences in host specificity and conglutinate morphology, Eckert (2003) and Barnhart and Eckert (2004) believe the type population in the Verdigris River system should retain the name Cyprogenia aberti. Further study of genetics and host requirements of populations in the Black River and populations east of the Mississippi are needed.  In a study of mitochondrial DNA sequences, conglutinate morphology, and host fish compatibility, two different mt DNA clades were found to exist sympatrically within most populations (also diagnosed by at least one morphological character- egg color), but the hypothesis of heritage infidelity of the two different mitochondrial genomes was tested and falsified.  However, populations from the major river systems utilized different host fish suggesting populations are not ecologically exchangeable with one another and may represent different taxa. 

A list of synonyms for this species can be found on The MUSSEL project web site (Graf and Cummings 2011).

Assessment Information [top]

Red List Category & Criteria: Data Deficient ver 3.1
Year Published: 2012
Date Assessed: 2012-03-05
Assessor(s): Cummings, K. & Cordeiro, J.
Reviewer(s): Bohm, M., Collen, B. & Seddon, M.
Contributor(s): Richman, N., 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.
Justification:
The taxonomic status of this species is not entirely resolved, which makes this species difficult to classify. Based on current knowledge, Cyprogenia aberti has been assessed as Data Deficient due to these ongoing taxonomic issues. This species is probably restricted to less than twenty severely fragmented populations where pollution and impoundments are continually degrading the quality of habitat and reducing the number of subpopulations. Some of these populations are genetically distinct, which further limits their viability. There have been documented reductions in range size and extirpations at local and state level. Conservation measures should be carried out to protect C. aberti and its habitat. Depending upon the resolution of this species' taxonomy, it is likely to qualify for a threatened category.
History:
1996 Endangered
1994 Indeterminate (Groombridge 1994)
1990 Endangered (IUCN 1990)
1988 Endangered (IUCN Conservation Monitoring Centre 1988)
1986 Indeterminate (IUCN Conservation Monitoring Centre 1986)

Geographic Range [top]

Range Description: This species has been revised taxonomically which has resulted in its distribution being drastically reduced. It is found in the highlands west of the Mississippi River in the Arkanssas river drainage (Turgeon et al. 1998, Serb 2006, Graf and Cummings 2007) and is only known from a few severely fragmented localities in Big Piney Creek (Davidson et al. 2000) and Point Remove Creek (University of Michigan, Museum of Zoology 2003 - Collection No. 98754). Although its overall range stretches more than 100,000 km2, it has a very discontinuous distribution.
Countries:
Native:
United States (Arkansas, Kansas, Missouri)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: This species is native to the Arkansas River system in Arkansas (Obermeyer et al. 1997) and is known only from approximately 20 localities in Big Piney Creek (Davidson et al. 2000) and Point Remove Creek (University of Michigan, Museum of Zoology 2003 - Collection No. 98754) though these may be different species (Corderio pers.comm 2011) and are in decline.
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: This species is found in gravel, and soft mud bottoms in medium sized rivers in flowing water only (NatureServe 2009). It is generally confined to shallow riffles and runs in predominantly clean, moderately compacted gravel-sand substrata (Obermeyer et al. 1997).

The fish hosts for this species include: the Banded Sculpin (Cottus carolinae), Log Perch (Percina caprodes), Fantail Darter (Etheostoma flabellare) and possibly the Goldfish (Carassius auratus) (Obermeyer et al. 1997).
Systems: Freshwater

Use and Trade [top]

Use and Trade: This species is not utilised.

Threats [top]

Major Threat(s): The species is threatened by impoundments and channelisation, gravel mining, agricultural practices (resulting in siltation and organic inputs), and the spread of the Zebra Mussel (Dreissena polymorpha) which now occurs in the Arkansas River drainage. Obermeyer (2000) found a reduction in the overall range associated with habitat loss due to large impoundments.

St. Francois, Reynolds, and Iron Counties in Missouri are located within the Southeast Missouri Lead Mining District, an area that was mined extensively for lead and zinc for more than a century. As a result of this, large amounts of metals which are toxic to this species, including cadmium, lead, zinc, and nickel were released and are continuing to be released into Missouri's environment (Mosby and Weber 2009).

Conservation Actions [top]

Conservation Actions: This species has been given a NatureServe Global Heritage Status Rank of G2G3Q - Imperilled to Vulnerable, but with questionable taxonomy which may reduce conservation status) (NatureServe 2009), an American Fisheries Society Status of Threatened (1 Jan 1993, Williams et al. in press, from Cummings pers. comm. 2011), and a previous IUCN Red List Category of Endangered (1996 ver 2.3) (Bogan 1996). This species is also listed under the Convention on International Trade in Endangered Species (CITES), Appendix II.

Few occurrences of this species are appropriately protected and managed. One occurrence in Kansas is protected by the Kansas Department of Wildlife and Parks. In southeastern Kansas, this species is protected from commercial harvest in the Verdigris River Freshwater Mussel Refuge (Miller 1993).

A current taxonomic challenge to this species was brought about by a phylogenetic analysis indicating this species is not a monophyletic group and may comprise two and possibly five distinct taxa, one of which includes the federally endangered Cyprogenia stegaria (Serb 2006). Serb (2006) recommends that the Arkansas, Black, and White drainages be managed as separate units for conservation. Conservation management plans for the Ouachita River system will be more complicated, because Ouachita populations contain two distantly related and genetically distinct lineages.

Further research is recommended into the taxonomy of this species, so that conservation efforts can be better directed.

Citation: Cummings, K. & Cordeiro, J. 2012. Cyprogenia aberti. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 01 October 2014.
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