Epioblasma florentina walkeri - (Wilson and H. W. Clark, 1914)
Tan Riffleshell
Synonym(s): Dysnomia florentina walkeri (Wilson and H. W. Clark, 1914) ;Dysnomia walkeri (Wilson and H. W. Clark, 1914) ;Epioblasma walkeri (Wilson and H. W. Clark, 1914) ;Plagiola florentina walkeri (Wilson and H. W. Clark, 1914)
Taxonomic Status: Accepted
Related ITIS Name(s): Epioblasma florentina walkeri (Wilson and H. W. Clark, 1914) (TSN 80314) ;Epioblasma walkeri (TSN 198394)
Unique Identifier: ELEMENT_GLOBAL.2.113818
Element Code: IMBIV16062
Informal Taxonomy: Animals, Invertebrates - Mollusks - Freshwater Mussels
Image 12004

Public Domain

 
Kingdom Phylum Class Order Family Genus
Animalia Mollusca Bivalvia Unionoida Unionidae Epioblasma
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Concept Reference
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Concept Reference: Turgeon, D.D., J.F. Quinn, Jr., A.E. Bogan, E.V. Coan, F.G. Hochberg, W.G. Lyons, P.M. Mikkelsen, R.J. Neves, C.F.E. Roper, G. Rosenberg, B. Roth, A. Scheltema, F.G. Thompson, M. Vecchione, and J.D. Williams. 1998. Common and scientific names of aquatic invertebrates from the United States and Canada: Mollusks. 2nd Edition. American Fisheries Society Special Publication 26, Bethesda, Maryland: 526 pp.
Concept Reference Code: B98TUR01EHUS
Name Used in Concept Reference: Epioblasma florentina walkeri
Taxonomic Comments: It has been suggested that Epioblasma capsaeformis may be a senior synonym of Epioblasma florentina walkeri (see Buhay et al., 2002), but molecular, morphological, and life history data from Jones (2004) and Jones et al. (2006) suggest they are distinct. A population from the upper Clinch River, Virginia (at Indian Creek), has been described as a separate subspecies, Epioblasma florentina aureola (Jones and Neve 2010). Variation in shell characters along with intergradation of nominal florentina and walkeri in the lower Holston River, suggest walkeri does not warrant subspecific status (Williams et al., 2008).
Conservation Status
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NatureServe Status

Global Status: G1T1
Global Status Last Reviewed: 28Apr2009
Global Status Last Changed: 25Nov1996
Rounded Global Status: T1 - Critically Imperiled
Reasons: This subspecies has declined severely from throughout the Cumberlandian region to only a few occurrences in the Big South Fork Cumberland River in Kentucky and Tennessee as extant populations in the Upper Clinch River in Virginia and Tennessee are likely a distinct undescribed subspecies.
Nation: United States
National Status: N1 (22Jul2003)

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Alabama (SX), Georgia (SX), Kentucky (S1), North Carolina (SX), Tennessee (S1)

Other Statuses

U.S. Endangered Species Act (USESA): LE: Listed endangered (23Aug1977)
U.S. Fish & Wildlife Service Lead Region: R4 - Southeast
IUCN Red List Category: CR - Critically endangered
Convention on International Trade in Endangered Species Protection Status (CITES): Appendix I
American Fisheries Society Status: Endangered (01Jan1993)

NatureServe Global Conservation Status Factors

Range Extent: <100 square km (less than about 40 square miles)
Range Extent Comments: Known from the Cumberland and Tennessee River systems. Specimens were historically collected from the Buffalo River in Perry Co., Tennessee (Parmalee and Bogan, 1998). It inhabited headwaters usually of the Flint River, Hurricane Creek, Bear Creek, main channel Tennessee River at Muscle Shoals, French Broad Creek in North Carolina, possibly Georgia (most of these now extirpated including a few specimens from Lookout Creek in the H.G. Athearn Collection, J. Cordeiro, pers. obs., 2006) (see Parmalee and Bogan, 1998). The federal recovery plan (USFWS, 1984) lists historical sites in the Stones, Harpeth, Middle Fork Holston Rivers, as well. In Kentucky, Cicerello and Schuster (2003) list it as sporadic in the upper Cumberland River below Cumberland Falls. Records of Epioblasma capsaeformis for North Carolina (Ortmann, 1914) have been shown to be misidentified Epiblasma florentina walkeri (J. Ratcliffe, NC NHP, pers. comm., 2007).

Area of Occupancy: 1-125 4-km2 grid cells
Area of Occupancy Comments: If occurrences in the upper Clinch River basin (Indian Creek, Middle Fork Holston, Hiwassee River), are accepted as a distinct subspecies (see Jones et al., 2006), this subspecies likely occupies only a small stretch of the Big South Fork Cumberland River.

Number of Occurrences: 1 - 5
Number of Occurrences Comments: A new population was found in the the Upper Clinch River and Indian Creek, Virginia (Jones et al., 2001). A population also exists in the Big South Fork Cumberland River, Tennessee and Kentucky and in Indian Creek (tributary of the upper Clinch River), Virginia (Jones, 2004; Jones et al., 2006). It was reported in the upper South Fork Holston (Stansbery and Clench, 1978) in Virginia. Additional populations may persist in the Hiwassee River, Polk Co., Tennessee (Clinch River drainage) (Jones, 2004). The other population from the Middle Fork Holston River in Virginia may no longer be extant but one male was collected live in 1997 (anonymous, 1997). A fresh dead female was collected in the Duck River in 1988 (OSM 29072). Based on molecular, morphological, and life history data, a population from the upper Clinch River, Virginia (at Indian Creek), is tentatively proposed as a separate subspecies [to be described as Epioblasma florentina aureola] based upon distinctiveness of molecular genetic markers, coloration of the mantle pad, glocidial size, and allopatric ranges in the Cumberlandian Region (Jones, 2004; Jones et al., 2006).

Population Size: Unknown
Population Size Comments: The population in Indian Creek was determined to be ~2000 adults (Rogers et al., 2001).

Number of Occurrences with Good Viability/Integrity: None to very few (0-3)
Viability/Integrity Comments: The Big South Fork Cumberland River populations in Tennessee and Kentucky are uncommon but reproducing as is the Indian Creek, Virginia population (which may be a separate subspecies) (Jones, 2004; Jones et al., 2006).

Overall Threat Impact: Very high - high
Overall Threat Impact Comments: The chemical Octocure 554, a rubber accelerant, was accidentally spilled into the Clinch River possible eliminating the only reproducing population (Hylton, 1998). Smith (1971) ranked the causes of extirpation or declines in fish species as follows: siltation, drainage of bottomland lakes, swamps, and prairie marshes, desiccation during drought, species introductions, pollution, impoundments, and increased water temperatures. All of these factors render habitats unsuitable, cause extirpations, and lead to the isolation of populations thereby increasing their vulnerability to extirpation for many aquatic species (including mussels) throughout North America. Zebra mussels, Dreissena polymorpha, have destroyed mussel populations in the Great Lakes and significantly reduced mussels in many of the large rivers of eastern North America. Zebra mussels have the potential to severely threaten other populations especially if they make their way into smaller streams. Pollution through point (industrial and residential discharge) and non-point (siltation, herbicide and fertilizer run-off) sources is perhaps the greatest on-going threat to this species and most freshwater mussels. Lowered dissolved oxygen content and elevated ammonia levels (frequently associated with agricultural runoff and sewage discharge) have been shown to be lethal to some species of freshwater naiads (Horne and McIntosh, 1979). Residential, mineral and industrial development also pose a significant threat. Rotenone, a toxin used to kill fish in bodies of water for increased sport fishery quality, has been shown to be lethal to mussels as well (Heard, 1970). Destruction of habitat through stream channelization and maintenance is still a threat in the Middle Fork Holston River (Dennis in Neves 1991). Dredging of streams has an immediate effect on existing populations by physically removing and destroying individuals. Dredging also affects the long-term recolonization abilities by destroying much of the potential habitat, making the substrates and flow rates uniform throughout the system. Industrial development in the towns of Marion and Chilhowie, Virginia also poses a threat. Natural predators include raccoons, otter, mink, muskrats, turtles and some birds (Simpson 1899; Boepple and Coker 1912; Evermann and Clark 1918; Coker, et al. 1921; Parmalee 1967; Snyder and Snyder 1969). Domestic animals such as hogs can root mussel beds to pieces (Meek and Clark 1912). Fishes, particularly catfish, Ictalurus spp.. and Ameirus spp., and freshwater drum, Aplodinotus grunniens, also consume large numbers of unionids.

Short-term Trend: Decline of >70%
Short-term Trend Comments: This subspecies once occurred throughout the Cumberlandian Region but is now confined to a few surviving populations (Jones, 2004; Jones et al., 2006).

Long-term Trend: Decline of >90%
Long-term Trend Comments: The status of the remaining populations is presently unknown due to the rarity of the mussel (Dennis in Neves, 1991). This species was once widespread throughout the Tennessee River drainage and had been collected fro the upper Clinch River, Tazewell Co., Virginia, Middle Fork Holston River in Smyth and Washington Cos., Virginia, and in the South Fork Holston River, Washington Co., Virginia. Tributaries of the Tennessee River in Alabama once contained populations of Epioblasma florentina florentina, including the Flint River and Hurricane Creek, a tributary of the Flint River in Madison Co., and Bear Creek, Franklin Co., Alabama. The only collections of E. f. florentina from the main channel of the Tennessee River were from the Muscle Shoals area and in archaeological deposits in Lauderdale and Colbert Cos., Alabama. Epioblasma florentina ranged throughout several of the tributaries of the Cumberland, but its total distribution is not well known (it was collected from Buck Creek, Pulaski Co., and Beaver Creek, Russell Co., and in the Cumberland River, Pulaski and Russel Cos., Kentucky). Another subspecies, Epioblasma florentina curtisi, is known from southwestern Missouri and northwestern Arkansas and may represent a disjunct population that was once continuous with the subspecies east of the Mississippi River. E. f. florentina is now extinct while E. f. curtisi and E. f. walkeri are extremely rare (Parmalee and Bogan, 1998). All former Georgia records are believed to be extirpated (J. Wisniewski, GA NHP, pers. comm., January 2007).

Environmental Specificity: Very narrow. Specialist or community with key requirements scarce.
Environmental Specificity Comments: The decline in the overall range of this species suggests that it is not tolerant of poor water quality. Sensitive to pollution, siltation, habitat perturbation, inundation, and loss of glochidial hosts.

Other NatureServe Conservation Status Information

Distribution
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Global Range: (<100 square km (less than about 40 square miles)) Known from the Cumberland and Tennessee River systems. Specimens were historically collected from the Buffalo River in Perry Co., Tennessee (Parmalee and Bogan, 1998). It inhabited headwaters usually of the Flint River, Hurricane Creek, Bear Creek, main channel Tennessee River at Muscle Shoals, French Broad Creek in North Carolina, possibly Georgia (most of these now extirpated including a few specimens from Lookout Creek in the H.G. Athearn Collection, J. Cordeiro, pers. obs., 2006) (see Parmalee and Bogan, 1998). The federal recovery plan (USFWS, 1984) lists historical sites in the Stones, Harpeth, Middle Fork Holston Rivers, as well. In Kentucky, Cicerello and Schuster (2003) list it as sporadic in the upper Cumberland River below Cumberland Falls. Records of Epioblasma capsaeformis for North Carolina (Ortmann, 1914) have been shown to be misidentified Epiblasma florentina walkeri (J. Ratcliffe, NC NHP, pers. comm., 2007).

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map
Endemism: endemic to a single nation

U.S. & Canada State/Province Distribution
United States ALextirpated, GAextirpated, KY, NCextirpated, TN

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
AL Limestone (01083)*, Madison (01089)*
KY McCreary (21147), Pulaski (21199)*, Russell (21207)*, Todd (21219)*, Wayne (21231)*
TN Davidson (47037)*, Marshall (47117)*, Maury (47119), Polk (47139), Robertson (47147)*, Rutherford (47149)*, Scott (47151), Sullivan (47163)*
VA Smyth (51173)*, Tazewell (51185)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
05 Upper Cumberland-Lake Cumberland (05130103)+*, South Fork Cumberland (05130104)+, Stones (05130203)+*, Harpeth (05130204)+*, Red (05130206)+*
06 South Fork Holston (06010102)+*, Upper Clinch (06010205)+, Hiwassee (06020002)+, Wheeler Lake (06030002)+*, Lower Elk (06030004)+*, Upper Duck (06040002)+, Lower Duck (06040003)+*
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: A medium-sized (7 cm) freshwater mussel with a brown to yellow colored shell with numerous green rays.
Reproduction Comments: Watson and Neves (1996; 1997) report the following fish as suitable glochidial hosts: Cottus spp., Etheostoma blennioides (greenside darter), Etheostome flabellare (fantail darter), Etheostoma rufilineatum (redline darter), and Etheostoma simoterum (snubnose darter). This species (population from Big South Fork Holston River, Tennessee/Kentucky) transformed in greatest numbers on the fantail darter Etheostoma flabellare, producing an average of 73% of juveniles and infrequently on the greenside darter, Etheostoma blennioides (10%) and redline darter, Etheostoma rufilineatum (17%) (Jones, 2004; Jones et al., 2006). Mantle pad descriptions and fish lures are described in Jones (2004) and Jones et al. (2006). Rogers et al. (2001) examined host suitability of the Indian Creek population and determined that glochidia transformed on E. flabellare, E. blennioides, E. rufilineatum, E. simoterum, and either Cottus bairdi or Cottus carolinae.
Habitat Type: Freshwater
Non-Migrant: N
Locally Migrant: N
Long Distance Migrant: N
Riverine Habitat(s): CREEK, MEDIUM RIVER, Riffle
Special Habitat Factors: Benthic
Habitat Comments: Found in headwaters, riffles, and shoals in sand and gravel substrates. (Bogan & Parmalee, 1983)
Economic Attributes Not yet assessed
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Management Summary Not yet assessed
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Population/Occurrence Delineation
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Group Name: Freshwater Mussels

Use Class: Not applicable
Minimum Criteria for an Occurrence: Occurrences are based on some evidence of historical or current presence of single or multiple specimens, including live specimens or recently dead shells (i.e., soft tissue still attached and/or nacre still glossy and iridescent without signs of external weathering or staining), at a given location with potentially recurring existence. Weathered shells constitute a historic occurrence. Evidence is derived from reliable published observation or collection data; unpublished, though documented (i.e. government or agency reports, web sites, etc.) observation or collection data; or museum specimen information.
Mapping Guidance: Based on the separation distances outlined herein, for freshwater mussels in STANDING WATER (or backwater areas of flowing water such as oxbows and sloughs), all standing water bodies with either (1) greater than 2 km linear distance of unsuitable habitat between (i.e. lotic connections), or (2) more than 10 km of apparently unoccupied though suitable habitat (including lentic shoreline, linear distance across water bodies, and lentic water bodies with proper lotic connections), are considered separate element occurrences. Only the largest standing water bodies (with 20 km linear shoreline or greater) may have greater than one element occurrence within each. Multiple collection or observation locations in one lake, for example, would only constitute multiple occurrences in the largest lakes, and only then if there was some likelihood that unsurveyed areas between collections did not contain the element.

For freshwater mussels in FLOWING WATER conditions, occurrences are separated by a distance of more than 2 stream km of unsuitable habitat, or a distance of more than 10 stream km of apparently unoccupied though suitable habitat. Standing water between occurrences is considered suitable habitat when calculating separation distance for flowing water mussel species unless dispersal barriers (see Separation Barriers) are in place.

Several mussel species in North America occur in both standing and flowing water (see Specs Notes). Calculation of separation distance and determination of separation barriers for these taxa should take into account the environment in which the element was collected. Juvenile mussels do not follow this pattern and juveniles are typically missed by most standard sampling methods (Hastie and Cosgrove, 2002; Neves and Widlak, 1987), therefore juvenile movement is not considered when calculating separation distance.

Separation Barriers: Separation barriers within standing water bodies are based solely on separation distance (see Separation Distance-suitable, below). Separation barriers between standing water bodies and within flowing water systems include lack of lotic connections, natural barriers such as upland habitat, absence of appropriate species specific fish hosts, water depth greater than 10 meters (Cvancara, 1972; Moyle and Bacon, 1969) or anthropogenic barriers to water flow such as dams or other impoundments and high waterfalls.
Separation Distance for Unsuitable Habitat: 2 km
Separation Distance for Suitable Habitat: 10 km
Alternate Separation Procedure: None
Separation Justification: Adult freshwater mussels are largely sedentary spending their entire lives very near to the place where they first successfully settled (Coker et al., 1921; Watters, 1992). Strayer (1999) demonstrated in field trials that mussels in streams occur chiefly in flow refuges, or relatively stable areas that displayed little movement of particles during flood events. Flow refuges conceivably allow relatively immobile mussels to remain in the same general location throughout their entire lives. Movement occurs with the impetus of some stimulus (nearby water disturbance, physical removal from the water such as during collection, exposure conditions during low water, seasonal temperature change or associated diurnal cycles) and during spawning. Movement is confined to either vertical movement burrowing deeper into sediments though rarely completely beneath the surface, or horizontal movement in a distinct path often away from the area of stimulus. Vertical movement is generally seasonal with rapid descent into the sediment in autumn and gradual reappearance at the surface during spring (Amyot and Downing, 1991; 1997). Horizontal movement is generally on the order of a few meters at most and is associated with day length and during times of spawning (Amyot and Downing, 1997). Such locomotion plays little, if any, part in the distribution of freshwater mussels as these limited movements are not dispersal mechanisms. Dispersal patterns are largely speculative but have been attributed to stream size and surface geology (Strayer, 1983; Strayer and Ralley, 1993; van der Schalie, 1938), utilization of flow refuges during flood stages (Strayer, 1999), and patterns of host fish distribution during spawning periods (Haag and Warren, 1998; Watters, 1992). Lee and DeAngelis (1997) modeled the dispersal of freshwater into unoccupied habitats as a traveling wave front with a velocity ranging from 0.87 to 2.47 km/year (depending on mussel life span) with increase in glochidial attachment rate to fish having no effect on wave velocity.

Nearly all mussels require a host or hosts during the parasitic larval portion of their life cycle. Hosts are usually fish, but a few exceptional species utilize amphibians as hosts (Van Snik Gray et al., 2002; Howard, 1915) or may metamorphose without a host (Allen, 1924; Barfield et al., 1998; Lefevre and Curtis, 1911; 1912). Haag and Warren (1998) found that densities of host generalist mussels (using a variety of hosts from many different families) and displaying host specialists (using a small number of hosts usually in the same family but mussel females have behavioral modifications to attract hosts to the gravid female) were independent of the densities of their hosts. Densities of non-displaying host specialist mussels (using a small number of hosts usually in the same family but without host-attracting behavior) were correlated positively with densities of their hosts. Upstream dispersal of host fish for non-displaying host specialist mussels could, theoretically, transport mussel larvae (glochidia) over long distances through unsuitable habitat, but it is unlikely that this occurs very often. D. Strayer (personal communication) suggested a distance of at least 10 km, but a greater distance between occurrences may be necessary to constitute genetic separation of populations. As such, separation distance is based on a set, though arbitrary, distance between two known points of occurrence.

Date: 18Oct2004
Author: Cordeiro, J.
Notes: Contact Jay Cordeiro (jay_cordeiro@natureserve.org) for a complete list of freshwater mussel taxa sorted by flow regime.
Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 02Jan2007
NatureServe Conservation Status Factors Author: Cordeiro, J.
Element Ecology & Life History Edition Date: 24Jan2008
Element Ecology & Life History Author(s): Cordeiro, J.

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

References
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  • Anonymous. 1997. Endangered Species Technical Bulletin, 22(2): .

  • Bogan, A.E. and P.W. Parmalee. 1983. Tennessee's rare wildlife. Vol. 2: The mollusks. Tennessee Wildlife Resources Agency and the Tennessee Conservation Department: Nashville, Tennessee. 123 pp.

  • Buhay, J.E., J.M. Serb, C. R. Dean, Q. Parham, and C. Lydeard. 2002. Conservation genetics of two endangered unionid bivalve species, Epioblasma florentina walkeri and E. capsaeformis (Unionidae: Lampsilini). Journal of Molluscan Studies, 68: 385-391.

  • Cicerello, R.R. and G.A. Schuster. 2003. A guide to the freshwater mussels of Kentucky. Kentucky State Nature Preserves Commission Scientific and Technical Series 7:1-62.

  • Frierson, L.S. 1927. A Classified and Annotated Checklist of the North American Naiades. Baylor University Press: Waco, Texas. 111 pp.

  • Jones, J.W. 2004. A holistic approach to taxonomic evaluation of two closely related endangered freshwater mussel species, the oyster mussel (Epioblasma capsaeformis) and tan riffleshell (Epioblasma florentina walkeri) (Bivalvia: Unionidae). MS Thesis, Virginia Polytechnic Institute and State University, Blacksburg, Virginia. 178 pp.

  • Jones, J.W., R.J. Neves, M.A. Patterson, C.R. Good, and A. DiVittorio. 2001. A status survey of freshwater mussel populations in the upper Clinch River, Tazewell County, Virginia. Banisteria, 17: 20-30.

  • Jones, J.W., R.J. Neves, S.A. Ahlstedt, and E.M. Hallerman. 2006. A holistic approach to taxonomic evaluation of two closely related endangered freshwater mussel species, the oyster mussel Epioblasma capsaeformis and tan riffleshell Epioblasma florentina walkeri (Bivalvia: Unionidae). Journal of Molluscan Studies, 72: 267-283.

  • Matthews, J.R. and C.J. Moseley (eds.). 1990. The Official World Wildlife Fund Guide to Endangered Species of North America. Volume 1. Plants, Mammals. xxiii + pp 1-560 + 33 pp. appendix + 6 pp. glossary + 16 pp. index. Volume 2. Birds, Reptiles, Amphibians, Fishes, Mussels, Crustaceans, Snails, Insects, and Arachnids. xiii + pp. 561-1180. Beacham Publications, Inc., Washington, D.C.

  • Ortmann, A.E. 1914. Studies in naiades (in partim). The Nautilus, 28: 28-34.

  • Ortmann, A.E. 1924. The naiad fauna of Duck River in Tennessee. The American Midland Naturalist, 9: 18-62.

  • Parmalee, P.W. and A.E. Bogan. 1998. The Freshwater Mussels of Tennessee. University of Tennessee Press: Knoxville, Tennessee. 328 pp.

  • Parmalee, P.W. and A.E. Bogan. 1998. The freshwater mussels of Tennessee. University of Tennessee Press, Knoxville, Tennesee. 328 pp.

  • Rogers, S.O., B.T. Watson, and R.J. Neves. 2001. Life history and population biology of the endangered tan riffleshell (Epioblasma florentina walkeri) (Bivalvia: Unionidae). Journal of the North American Benthological Society, 20(4): 582-594.

  • Stansbery, D. H. and W. J. Clench. 1977 [1978]. The Pleuroceridae and Unionidae of the Upper South Fork Holston River in Virginia. Bulletin of the American Malacological Union 1977:75-79.

  • Turgeon, D.D., J.F. Quinn, Jr., A.E. Bogan, E.V. Coan, F.G. Hochberg, W.G. Lyons, P.M. Mikkelsen, R.J. Neves, C.F.E. Roper, G. Rosenberg, B. Roth, A. Scheltema, F.G. Thompson, M. Vecchione, and J.D. Williams. 1998. Common and scientific names of aquatic invertebrates from the United States and Canada: Mollusks. 2nd Edition. American Fisheries Society Special Publication 26, Bethesda, Maryland: 526 pp.

  • U.S. Fish and Wildlife Service (USFWS) (Neves, R.J.). 1984. Recovery plan for the tan riffle shell mussel; Epioblasma walkeri. U.S. Fish and Wildlife Service, Region 4, Atlanta, Georgia.

  • Watson, B.T. and R.J. Neves. 1996. Host fishes for two federally endangered species of mussels. Triannual Unionid Report, 10: 13.

  • Watson, B.T. and R.J. Neves. 1997. Life history characteristics of two federally endangered freshwater mussels (family Unionidae). Association of Southeastern Biologists Bulletin, 44(2): 110.

  • Williams, J. D., A. E. Bogan, and J. T Garner. 2008. Freshwater mussels of Alabama & the Mobile Basin in Georgia, Mississippi, & Tennessee. University of Alabama Press, Tuscaloosa, Alabama. 908 pages.

  • Williams, J.D., A.E. Bogan, and J.T. Garner. 2008. Freshwater Mussels of Alabama & the Mobile Basin in Georgia, Mississippi & Tennessee. University of Alabama Press: Tuscaloosa, Alabama. 908 pp.

  • Williams, J.D., M.L. Warren, Jr., K.S. Cummings, J.L. Harris, and R.J. Neves. 1993b. Conservation status of freshwater mussels of the United States and Canada. Fisheries 18(9): 6-22.

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