endemic to a single nation
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) This species was once known from the upper Mississippi River drainage and the St. Lawrence River drainage, from western New York west to Michigan, Wisconsin, Iowa, and Kansas, south to Arkansas and Alabama (Burch, 1975). Historically, it occurred throughout much of the Ohio River drainage. It is now quite sporadic with occurrences in the Ohio River and Muskingum River (Watters, 1995) and apparently extirpated from the Wabash and some other tributaries in Ohio. Localized occurrences exist in the Green, Tennessee and Cumberland river reservoirs and a few Tennessee River tributaries. Mathiak (1979) cites it as scattered over 30 (of 641) sites in Wisconsin but noted identification difficulties. It is somewhat widespread in Alabama but is considered a state watch list species due to recent declines (Mirarchi et al., 2004). In Kentucky, it is generally distributed to occasional nearly statewide (Cicerello and Schuster, 2003).
Length: 11.5 cm
The shell is similar to several Pleurobema spp. and Fusconaia ebena (Lea, 1831). The latter species and P.COCCINEUM have more rounded outlines, low broadly rounded posterior ridges, and little, if any, development of the radial sulci anterior to the posterior ridge. Pleurobema plenum has a more angular appearance, broader and more flattened beaks, and a disinctively angular posterior ridge with a narrow and poorly developed radial sulcus (the sulcus is often more strongly developed ventrally). Pleurobema pyramidatum resembles an elongate scaline triangle, almost elliptical in appearance. Its posterior ridge is rounded but distinct with a shallow sulcus anteriorly. These features are most pronounced in the region of the beaks, becoming flattened and obscurred ventrally. Height: 95mm
Habitat and Ecology
Habitat Type: Freshwater
Comments: This species primarily inhabits large rivers but may be found in medium-sized rivers. It is also tolerant of some reservoir environments. In lotic situations it is found in or immediately above riffles in heterogenous assemblages of gravel, cobble, and boulder. It also occurs in some habitats with greater depth and substrates of mud/sand/gravel but seems to require flowing water. In reservoirs, it tends to occur in the sublotic areas of dam tailwaters and may be in some overbank beds (Gordon and Layzer, 1989).
Non-Migrant: No. All populations of this species make significant seasonal migrations.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
This species is probably rather sessile with only limited movement through the substrate. Passive downstream movement may occur when mussels are displaced from the substrate during flooods. Major dispersal occurs while glochidia are encysted on their hosts.
Comments: Larvae (glochidia) of freshwater mussels generally are parasitic on fish and display varying degrees of host specificity. No specific trophic studies have been conducted on this species. General literature claims that mussels are filter-feeders that remove phytoplankton from the water column. These assumptions are based on casual observations on mussels in situ and a few examinations of rectal contents. Baker (1928) speculated that detritus was the primary energy source. This has been substantiated by James (1987) and correlates well with observed microhabitat utilization. This suggests that musssels may occupy a variety of guilds such as postulated for the Sphaeriidae (see Lopez and Holopaien, 1987; Gordon and Layzer, 1989).
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: 81 - 300
Comments: Number of occurrences is difficult to assess with present data. Increasingly, this species is found to be rare in non-impounded areas and occurrences in some reservoirs are poorly documented. Significant declines have been noted in reservoirs with commercial harvest. In Tennessee, where it formerly was widespread in the Cumberland, Tennessee, Little Tennessee, Holston, Nolichucky, Elk, Duck, Clinch, French Broad and Hatchie Rivers, it is now restricted to a limited number of sites within these systems and has been extirpated from the Little Tennessee and French Broad Rivers (Parmalee and Bogan, 1998). In Alabama, it is found throughout the Tennessee River in northern Alabama and was historically the most abundant species there, but today is found only in small numbers in tailwaters of Guntersville and Wilson dams (Mirarchi, 2004; Williams et al., 2008) and Paint Rock River (Ahlstedt, 1996). In Arkansas, it occurs in the Mississippi Alluvian Plain (St. Francis and White River drainages- see Gordon, 1982) Ozark Highlands (White River drainage), and South Central Plains (Ouachita River drainage), although some records may represent Pleurobema rubrum (Anderson, 2006). It has been collected in Kentucky in the Red (Clark, 1988), Middle Green and Barren Rivers (Cochran and Layzer, 1993), but is generally distributed to occasional nearly statewide (Cicerello and Schuster, 2003). Oklahoma distribution for Pleurobema cordatum includes: Chikaskia (as P. coccineum), Little, Kiamichi, Verdigris, Neosho, Poteau, Mountain Fork, and Spring Rivers (Branson, 1983), however the northern to northeast occurrences are likely Pleurobema sintoxia. In Illinois, it is now restricted to the Ohio River where it is generally distributed (Cummings and Mayer, 1997). In Ohio, it is limited to the lower Muskingum River, Big Darby Creek, and a few sites in the Ohio River (Watters, 1995; Watters et al., 2009). This species was recently reported from the first time in Ohio Brush Creek, Ohio (Matter et al., 2006). In West Virginia, it occurs in the Upper Ohio/Kanawha (Zeto et al., 1987). In Kentucky, Cicerello and Schuster (2003) list distribution as generally distributed to occasional nearly statewide while Clark (1987) list it in their study of the Red River drainage. In Wisconsin, Mathiak (1979) cites it from 30 localities across the state including the Mississippi and lower Wisconsin Rivers, and sites in northwestern and southeastern Wisconsin.
Comments: Population size is difficult to assess due to the area involved and lack of quantitative estimates. Sharp declines have been noted in both general occurrence and in commercial harvests. Some populations may not be reproducing successfully. Scruggs (1960) estimated it comprised almost 53% of the mussel fauna in Guntersville Dam tailwaters in the Tennessee River (20,566,000 individuals in an 8 mile stretch below the dam in 1956-1957); while in 1997 it comprised only 6% of the fauna (J. Garner in Williams et al., 2008) (no individuals in 1991- Ahlstedt and McDonough, 1993).
No ecological studies have specifically considered this species. Representative densities of disturbed populations have been estimated in Jenkinson (1988) and Jenkinson and Ahlstedt (1988), and data relative to several environmental parameters were presented in Yokley (1972) but were not correlated to the specific occurrence of mussels. Williams and Schuster (1989) considered demographics of Ohio River populations.
Life History and Behavior
Comments: Little is known concerning the phenology of mussels other than when eggs/glochidia are held in the branchial marsupia. Being poikilothermic, activity levels would expectedly be reduced greatly during cold temperature months.
Pleurobema cordatum is a short-termed brooder with embryonic or larval forms reported from echtobranchous marsupia between April and August. Previously, Notropis ardens (rosefin shiner)was the only fish on which successful metemorphosis of glochidia has been reported (Yokley, 1972; Fuller, 1974). Previously, Lepomis macrochirus (bluegill) had been also considered to serve as a host (Fuller, 1974; Gordon and Lazer, 1989), but this was from a report in Surber (1913) for "Quadrula solida" (= Pleurobema catillua) which is a junior synonym of Pleurobema coccineum. The distribution of P. cordatum is considerably larger and occupies a greater range of habitats than Notropis ardens, indicating that other hosts exist for this mussel. Recently, other host fish were found to be creek chub (Semotilus atromaculatus), guppy (Lebistes reticulatus), brook stickleback (Culaea inconstans); also no support for previously reported bluegill (Lepomis macrochirus) (Watters and Kuehn, 2004). New host fish confirmation from Watters et al. (2005) include: brook stickleback (Culaea inconstans), creek chub (Semotilus atromaculatus), and guppy (Lebistes reticulatus).
Molecular Biology and Genetics
Barcode data: Pleurobema cordatum
There are 3 barcode sequences available from BOLD and GenBank. Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species. See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
Statistics of barcoding coverage: Pleurobema cordatum
Public Records: 3
Specimens with Barcodes: 3
Species With Barcodes: 1
IUCN Red List Assessment
Red List Category
Red List Criteria
- Needs updating
National NatureServe Conservation Status
Rounded National Status Rank: N4 - Apparently Secure
NatureServe Conservation Status
Rounded Global Status Rank: G4 - Apparently Secure
Reasons: This species has become increasingly rare in occurrence and density. Of the remaining populations, some may be incapable of successful reproduction and long-term viability of many populations is questionable. However, despite sharp declines in numbers, it is still relatively wide-spread in its historic range across much of the United States with subnational extirpations in the far northeastern portion of its range.
Global Short Term Trend: Decline of 10-30%
Comments: This species has been extirpated from or occurs in greatly reduced numbers through considerable portions of its historical range (e.g., Cummings et al., 1987, 1988; Pardue, 1981; Jenkinson, 1988; Jenkinson and Ahlstedt, 1988; Mirarchi et al., 2004). For example, Pleurobema cordatum in the Kentucky Resevoir section of the Tennessee River has declined from the dominant mussel species (Scruggs, 1960) to a rather rare component of the fauna (Layzer and Gordon, 1990). Williams and Schuster (1989) have documented temporal changes in relative abundance in the Ohio River bordering Kentucky, and it appears to have been extirpated completely from the Wabash River basin. Parmalee and Bogan (1998) claim it has been extirpated from the Little Tennessee and French Broad Rivers and is now a relict population in the Tennessee River upstream from Chattanooga. It is now quite sporadic with occurrences in the Ohio River and Muskingum River (Watters, 1995) and apparently extirpated from the Wabash and some other tributaries in Ohio. Scruggs (1960) estimated it comprised almost 53% of the mussel fauna in Guntersville Dam tailwaters in the Tennessee River (20,566,000 individuals in an 8 mile stretch below the dam in 1956-1957); while in 1997 it comprised only 6% of the fauna (J. Garner in Williams et al., 2008) (no individuals in 1991- Ahlstedt and McDonough, 1993).
Global Long Term Trend: Decline of 30-50%
Comments: This species is extirpated in Pennsylvania (Bogan, 1993; Spoo, 2008) where it formerly occurred in the Upper Ohio, Middle Allegheny-Redbank, and Lower Monongahela drainages (Ortmann, 1919) as well as New York where it formerly occurred in the far western portion of the state (Strayer and Jirka, 1997). In Alabama, it is found throughout the Tennessee River in northern Alabama and was historically the most abundant species there, but today is found only in small numbers in tailwaters of Guntersville and Wilson dams (Mirarchi, 2004).
Degree of Threat: B : Moderately threatened throughout its range, communities provide natural resources that when exploited alter the composition and structure of the community over the long-term, but are apparently recoverable
Comments: Chemical and organic pollution, alteration and inundation of river channels (including loss of glochidial hosts), siltation from various sources, toxic run-off from mines, die-offs of various unidentified causes (Yokley, 1972; Neves, 1987) and commercial harvest of shells have and continue to severely impact this species. It is also considered a prime commercial shell. Impoundment has caused the decline of this species in many areas (Parmalee and Bogan, 1998).
Biological Research Needs: Determine habitat preferences and environmental tolerances, particularily to pollutants and siltation. Re-examine and continue research on reproductive biology and potential glochidial hosts.
Global Protection: Few (1-3) occurrences appropriately protected and managed
Comments: Apparently, this species persists at TNC's Pendleton Island Preserve. It also may occur in some of the mussel preserves on the Tennessee and Cumberland rivers. Moratoria on commercial shelling may be placed on sections of Green River. Although once an important commercial species, it was removed from the list of legally harvestable mussels in Alabama in 2004 (Williams et al., 2008).
Needs: All populations should receive protection through acquisition, easement, registry, and working with local, state, and federal government agencies on issues relating to development, water quality, river designation, etc. Besides preservation and restoration of habitat, commercial harvesting should be strictly controlled or curtailed.
- Bogan, A.E. & Seddon, M.B. 1996. Pleurobema cordatum. 2006 IUCN Red List of Threatened Species. Downloaded on 7 August 2007.
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Names and Taxonomy
Comments: Is part of a complex of closely related species or ecophenotypes that includes P. cordatum, P. coccineum, P. plenum, and P. rubrum (Strayer and Jirka 1997). The identity of this species has been confused at times because of lumping by some authors of several closely related species either as synonyms under, or as subspecies of, Pleurobema cordatum (e.g., Ortmann, 1918; Burch, 1975). As a result, museum collections labeled as this species may contain only it, a jumble of several subspecies, or other species excluding P. cordatum. Published records also must be suspect.er species excluding P. cordatum. Published records also must be suspect.
The members of the genus Pleurobema are among the most difficult to identify in North America. Arguments arise even among taxonomists regarding the "species" represented in the genus Pleurobema. Stansbery (1983) summarized many of the problems and identified a few of the shell characters used to separate Pleurobema sintoxia from the morphologically similar and often co-occurring Pleurobema plenum, Pleurobema cordatum, and Pleurobema rubrum. A few "morphs" have been variously identified and named but no rigorous genetic, anatomic, or conchologic study has ever been published on this group to help elucidate species boundaries or relationships.