Fusconaia cuneolus 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Mollusca Bivalvia Unionoida Unionidae

Scientific Name: Fusconaia cuneolus (Lea, 1840)
Common Name(s):
English Finerayed Pigtoe, Fine-rayed Pigtoe, Finerayed Pigtoe Pearlymussel, Fine-rayed Pigtoe Pearly Mussel
Taxonomic Notes: Campbell et al. (2005) found this species to be closely related to Fusconaia cor, but held it up as distinct.

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: Endangered B2ab(i,ii,iii,iv) 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., De Silva, R., Milligan, HT, Herdson, R., Thorley, J., McMillan, K., Collins, A., Offord, S. & Duncan, C.
Fusconaia cuneolus has been assessed as Endangered under criterion B2ab(i,ii,iii,iv). The species currently only occurs in four remaining fragmented locations, with an estimated area of occupancy of no more than 500 km2. Because of its sensitivity to changes in water quality, the species has and continues to decline, in terms of reductions in area of occupancy, extent of occurrence, quality of habitat and number of sub-populations, due to river impoundments, siltation, and pollution. It is likely that this species will qualify for Critically Endangered A2ac once sufficient population information is established.
Previously published Red List assessments:

Geographic Range [top]

Range Description:Historically, this species was widespread in tributaries of the Tennessee River system in Tennessee (above the Mussel Shoals area), Virginia, and Alabama including the Tennessee, Flint, Paint Rock, Elk, Nolichucky, Clinch, Emory, Powell, Holston, North Fork Holston Rivers; Big Moccasin Creek (Virginia), Poplar Creek (Tennessee), Bear Creek (Alabama), Limestone Creek (Alabama), Hurricane Creek (Alabama), and Little River (Tennessee) (USFWS 1984). It currently persists in portions of the Clinch and Powell rivers, the North Fork of the Holston, and in the Paint Rock River. The largest population resides in the Clinch River, but it is reproductively isolated from the Powell River population (Neves 1991). It has been extirpated from Tennessee River proper with a population extant in Paint Rock River in Alabama (Mirarchi et al. 2004).
Countries occurrence:
United States (Alabama, Tennessee, Virginia)
Additional data:
Estimated area of occupancy (AOO) - km2:500Continuing decline in area of occupancy (AOO):Yes
Estimated extent of occurrence (EOO) - km2:1000
Continuing decline in extent of occurrence (EOO):Yes
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:No surveys have been conducted throughout the entire range of this species. Surveys in Virginia (1980) indicated that twelve sites were scattered throughout the Clinch River (Jones et al. 2001). It was reported recently in Copper Creek (Upper Clinch drainage) in Virginia (Fraley and Ahlstedt 2000). Populations outside the Clinch River (Powell River, Hancock and Claiborne Cos., Tennessee; see Parmalee and Bogan 1998) are either extirpated, have poor viability, or no viability. Such sites include the North Fork Holston River at Cloud Ford, Tennessee; three sites in the Powell River in Tennessee and Fletcher Ford, Virginia; Elk River, Paint Rock River, Little River (Blount Co., Tennessee), Sequatchie River near Dunlop, Tennessee (USFWS 1984); but all of these have little or no viability. In Alabama, it was once extant across the northern part of the state but is now only found in the Paint Rock River (Mirarchi 2004).

Bruenderman and Neves (1993) conducted life history studies on a healthy population from the Clinch River in Scott Co., Virginia. Here, cohort structure of live specimens and collections of valves indicate populations in the Clinch River are declining (Bruenderman and Neves 1993). Pendleton Island in the Clinch River, Virginia, is a TNC preserve (Bruenderman and Neves 1993) and has a reproducing population (gravid females). These two sites are very close and are essentially one population. Outside the Clinch River, viability generally does not exist (USFWS 1984).

Overall the species has suffered a significant reduction in range. Most former sites in Tennessee no longer maintain populations (Parmalee and Bogan 1998).
Surveys of 201 km of the Elk River from the Alabama border through Tennessee revealed a single site with this species in Lincoln Co., Tennessee (Ahlstedt 1983). It has been extirpated throughout most of its former range in Tennessee, with the last remaining population in the Clinch and Powell Rivers (Hancock and Claiborne Cos.) and survival of these populations remains questionable (Parmalee and Bogan 1998). The only known extant Alabama population of this species is in the Paint Rock River system (Williams et al. 2008).
Current Population Trend:Decreasing
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:This species occurs in shoal habitats of creeks and rivers. Historical distribution data suggest that it occurred in smaller streams than many other species of the genus. It prefers stable gravel substrates in moderate current (Williams et al. 2008), and was recorded as inhabiting clear, high gradient streams in firm cobble and gravel substrates (Neves and Moyer 1988).

Bruenderman and Neves (1993) detailed the life history of the species in the Clinch River, southwestern Virginia. It is a short-term brooder, apparently spawning in early May, with females gravid from mid-May through early August. Developing embryos are bound in conglutinates and change color from pink to orange to light peach as they mature. However, mature glochidia are discharged in a loose, gelatinous matrix instead of well-defined conglutinates. Fecundity was assessed in one gravid female, which contained approximately 113,000 embryos. Glochidia were recovered from stream drift as early as late May and as late as mid-August. Ortmann (1921) reported a similar gravid period for the species, from mid-May through mid-July (Williams et al. 2008).

Fishes on which natural infestations of glochidia have been observed and confirmed in laboratory conditions include Cyprinella galactura (Whitetail Shiner), Nocomis micropogon (River Chub) and Notropis leuciodus (Tennessee Shiner, Cyprinidae; Bruenderman and Neves 1993). Additional species found to serve as glochidial hosts in laboratory trials are Cottus bairdii (Mottled Sculpin, Cottidae); and Campostoma anomalum (Central Stoneroller), Luxilus albeolus (White Shiner), Notropis telescopus (Telescope Shiner) and Pimephales notatus (Bluntnose Minnow, Cyprinidae; Bruenderman and Neves 1993, Williams et al. 2008).

Based on examination of thin sections of shell, this species was found to live at least 32 years (Bruenderman and Neves 1993, Williams et al. 2008).


Continuing decline in area, extent and/or quality of habitat:Yes
Congregatory:Congregatory (and dispersive)

Use and Trade [top]

Use and Trade: This species is not utilised.

Threats [top]

Major Threat(s): This species is sensitive to changes in water quality and has declined due to impoundments, siltation, and pollution. The remnant population in the Powell River may be threatened by oil and gas drilling and coal mining (Neves 1991). The Clinch River population was reduced by toxic discharges and spills prior to 1972. The invasion of the Asian clam, and the possible invasion of the zebra mussel, also threaten remaining populations. Reasons for decline listed in the recovery plan include: impoundment, siltation, and pollution (USFWS 1984).

Conservation Actions [top]

Conservation Actions: This species was listed as Endangered in 1976 throughout its range, except in the free-flowing reach of the Tennessee River from the base of Wilson Dam downstream to the backwaters of Pickwick Reservoir and the lower 5 river miles of all tributaries to this reach in Colbert and Lauderdale Counties, Alabama (USFWS 2001). Williams et al. (2010) lists this species as endangered according to the AFS assessment.

A recovery plan (USFWS 1984) was created which outlines the following objectives: (1) preserve populations and habitats in the North Fork Holston, Powell, Clinch (including tributaries Little River and Copper Creek), Elk, Paint Rock, Little, and Sequatchie Rivers, (2) conduct life history research on the species, to include gametogenesis, fish host identification, age class structure, growth rate, life tables, and mortality factors, (3) determine the feasibiltiy of introducing the species into one additional stream/river or establishing a viable population in an appropriate section of a stream/river where it currently resides; implement such an activity where feasible, (4) outline and implement a schedule to monitor population levels and trends in extant and introduced populations and population centers, (5) evaluate the success of individual activities and overall success of the recovery program; recommend revisions or additional actions as necessary to recover the species.

The USFWS (2006), in cooperation with the State of Tennessee and Conservation Fisheries, Inc., proposes to reintroduce this species into its historical habitat in the free-flowing reach of the French Broad River below Douglas Dam to its confluence with the Holston River, Knox County Tennessee, and in the free-flowing reach of the Holston River below Cherokee Dam to its confluence with the French Broad River (USFWS 2006).

Nonessessential Experimental Populations (NEPs) have been established in the Tennessee River below Wilson Dam, Colbert and Lauderdale Cos., Alabama, extending 13.4 km and including the lower 8 km of all tributaries that enter the Wilson Dam tailwaters (USFWS 2001). Nonessessential Experimental Populations (NEPs) have been proposed for reintroduction into the free-flowing reach of the French Broad River below Douglas Dam (Knox and Sevier Cos., Tennessee) to its confluence with the Holston River, Knox Co., Tennessee, and in the free-flowing reach of the Holston River below Cherokee Dam to its confluence with the French Broad River (Knox, Grainger, and Jefferson Cos., Tennessee), where this species currently does not exist (USFWS 2006). Pendleton Island in the Clinch River, Virginia, is a TNC preserve (Bruenderman and Neves 1993) and has a reproducing population (gravid females).

Further research regarding the taxonomy, ecology, population and threats impacting this species is required. The implementation of conservation strategies are also needed to protect this species, including site and species national protection and population establishment and augmentation where appropriate.

Citation: Cummings, K. & Cordeiro, J. 2012. Fusconaia cuneolus. The IUCN Red List of Threatened Species 2012: e.T8773A3146130. . Downloaded on 23 June 2018.
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