This taxon, originally known as Margaritifera monodonta, was removed from the 1996 Red List but kept on the Mollusc SG database as Not Evaluated.

Cumberlandia monodonta has been assessed as Endangered under A2ac, because of estimated and, in parts of its range, observed declines in individuals, populations and area of occupancy of between 30-70% over the past century. Assuming that the average number provides us with a good estimate of decline, and given the long generation length of this species, a 50% decline over the past three generations is inferred. The species is now extirpated from several U.S. states (Indiana, Kansas, Nebraska, Ohio) and many of the remaining populations have poor or no viability. The species has largely been reduced to a relatively few disjunct sites, some of which may not be capable of reproduction either through loss of fish hosts or adverse environmental conditions (e.g., hypolimnetic release from reservoirs). Only the Gasconade and Meramec Rivers of Missouri and perhaps also in the Upper Clinch River, Tennessee are fairly stable for now, with the remaining populations in decline. Further research and protection is required in order to offer this species adequate conservation protection.

In 1996 the species was considered 'Near Threatened' in a review by Bogan and Seddon (Seddon, pers. comm., 2012), on grounds of population loss over the region (see 1996 & 2000 Red List). However this more comprehensive review provides more data on range and decline rates allowing review and confirmation of higher threat status.

Historically, this species is known from 45 streams in twelve states including: the upper Mississippi River system (Mississippi River); the lower Missouri River system, from southern Minnesota and Wisconsin (Cummings and Mayer 1992, Williams et al. 2008) south to the Ouachita River drainage in south-central Arkansas; and in West Virginia downstream to the mouth of the Ohio River, including some tributaries (Cicerello et al. 1991, Cummings and Mayer 1992, Williams et al. 2008); the Cumberland River system (Cumberland River) downstream of Cumberland Falls (Cicerello et al. 1991, Parmalee and Bogan 1998); the Tennessee River system (Tennessee River; Neves 1991, Parmalee and Bogan 1998); and the lower Mississippi River system (Mulberry, Ouachita Rivers; Butler 2003, USFWS 2003).
There has been a decline documented throughout its former range over the last century (Baird 2000), except in the Gasconade River, Missouri. Ahlstedt et al. (2004) recently reported sporadic occurrences (two recent) from the Duck River in a reach less than 30 miles long. It is still widely distributed but absent from many of its historical areas. Many streams have had no reports for decades and several have only single occurrences (Butler 2003).
As a result, extant populations of the species are known from twenty streams in eleven states. These include the following stream systems (with tributaries): the upper Mississippi River system (Mississippi River [St. Croix, (Rush Creek), Chippewa, Meramec (Bourbeuse, Big Rivers) Rivers]; the lower Missouri River system (Gasconade [Big Piney River, Osage Fork] River); the lower Ohio River system (lowermost Ohio River [Kanawha, Green Rivers]); the Cumberland River system (Caney Fork); the Tennessee River system (Tennessee River [Clinch, Nolichucky, Duck Rivers]); and the lower Mississippi River system (Mulberry, Ouachita Rivers).
In terms of state presence, the twenty extant populations occur in the following eleven states (respective streams are given): Alabama (Tennessee River), Arkansas (Mulberry, Ouachita Rivers- both single sites only; Harris et al. 1997), Illinois (Mississippi, Ohio Rivers), Iowa (Mississippi River), Kentucky (Ohio, Green Rivers), Minnesota (Mississippi, St. Croix Rivers; Rush Creek), Missouri (Mississippi, Meramec, Bourbeuse, Big, Gasconade, Big Piney Rivers; Osage Fork), Tennessee (Tennessee, Clinch, Nolichucky, Duck Rivers; Caney Fork), Virginia (Clinch River), West Virginia (Kanawha River), and Wisconsin (Mississippi, St. Croix, Chippewa Rivers) (NatureServe 2009). Based on this and county-level occurrences, the estimated extent of occurrence is likely to be larger than 120,000 km² (this estimate is allowing for large discontinuities in the species' range).

The species is evidently absent from hundreds of river miles and from numerous reaches of habitat in which it occurred historically. Of the twenty extant populations, seven are represented by only a single specimen each and are probably not viable (Butler 2003). Although many populations have been extirpated for decades, most surviving populations are facing significant threats. There are relatively strong populations in the Meramec and Gasconade Rivers in Missouri, in the St. Croix River in Minnesota/Wisconsin, and perhaps also in the Upper Clinch River in Tennessee (see Butler 2003, USFWS 2003). Ahlstedt et al. (2004) recently reported sporadic occurrences (two recent) from the lower Duck River in a reach less than 30 miles long with historical occurrences in the upper Duck as well. Alabama populations are now restricted to Guntersville Dam and Wilson Dam tailwaters only (Williams et al. 2008).

Most or all of the 21 known populations of this species face serious threats to their continued existence. Only three or four populations could be characterized as large and viable and each of these faces serious threats (see USFWS 2003). Oesch (1995) cites a fairly large population in the Meramec River and Gasconade River in Missouri. Also the Upper Clinch River in Tennessee may have reasonable viability (USFWS 2003).

Population size is difficult to assess due to the wide range of this species and the fact that there are no accurate assessments of populations at any site. Several recent reports are based on finds of single mussels. TVA data definitely indicates rapidly declining populations in the upper Clinch River. In Arkansas, where this species was once thought extirpated, it is only known from the Ouachita River (two sites represented by one single live specimen each) and a single site in the Mulberry River (also a single live specimen only) (Harris et al. 1997). 

Rapid population declines have been documented throughout its former range, except in the Gasconade River, Missouri. For example, in Illinois where it was formerly present in eight drainages, it is now restricted to the Ohio and Mississippi Rivers, where it is sporadic and very rare (Cummings and Mayer 1997).  In the last century, the species was extirpated from extreme southeastern Nebraska and eastern Kansas both on the Missouri border (Butler 2003). In Alabama it was known only from the Tennessee and Elk Rivers, but is now restricted to Guntersville Dam and Wilson Dam tailwaters only (Williams et al. 2008). 

Declines have been estimated as ranging between 30-70% by NatureServe (2009). Although these declines have occurred over the past century, this is a long lived species with the average age being 20-35 years and the oldest individuals being about 56 years or even older (Baird 2000). There are several large and stable populations (of the 20 or so extant populations, probably 7-10 are viable and many of these are considered abundant) (J. Cordeiro pers. comm. 2012)

The Spectaclecase occurs in large rivers and is a habitat-specialist, relative to other mussel species. This species is confined to flowing water systems only (USFWS 2003). Baird (2000) noted its occurrence on outside river bends below bluff lines. It seems to most often inhabit riverine microhabitats that are sheltered from the main force of current. Utterback's (1915) record of this species in the Northwest Missouri Lakes is puzzling, but may refer to seasonally flooded oxbow lakes along the Missouri River. It occurs in substrates from mud and sand to gravel, cobble, and boulders in relatively shallow riffles and shoals with slow to swift current (Buchanan 1980, Parmalee and Bogan 1998, Baird 2000). According to Stansbery (1967), the Spectaclecase is usually found in firm mud between large rocks in quiet water very near the interface with swift currents. Specimens have also been reported in tree stumps, root masses, and in beds of rooted vegetation (Stansbery 1967, Oesch 1995). Similar to other margaritiferids, the Spectaclecase tends to be found in aggregations (Gordon and Layzer 1989), particularly under slab boulders or bedrock shelves (Call 1900, Hinkley 1906, Buchanan 1980, Parmalee and Bogan 1998, Baird 2000), where they are protected from the current. Unlike most species that move about to some degree, the Spectaclecase may seldom, if ever, move except to burrow deeper; they may die from stranding during droughts (Oesch 1995).

The life history of this species in the Gasconade and Meramec rivers, Missouri, was reported by Baird (2000). That population had a 1:1 sex ratio, no sexual dimorphism in shell morphology and no hermaphroditic individuals. However, occasional hermaphrodites have been reported (van der Schalie 1966). The age at sexual maturity in the Gasconade and Meramec rivers is four to five years for males and five to seven years for females, but inference from growth rate suggests major investment in reproduction may not occur until after about 10 years. Based on maximum ages recorded by Baird (2000) of 56 years, this would put the generation length (average age of parent) at 30-33 years (and three generations at 90-100 years). This species is a long-term brooder. In the Gasconade and Meramec rivers, females brooded eggs between September and December, and mature glochidia in April and May. Conglutinates are white, branched and feathery. Fecundity was reported to range from approximately 2,000,000 to more than 9,000,000 (Baird 2000, Williams et al. 2008). It has been suggested that the species may produce two broods per year (Howard 1915, Gordon and Smith 1990), but Baird (2000) reported no evidence of biannual reproduction.

Baird (2000) reported no successful transformations of glochidia in laboratory host fish trials. However, natural infestations of the species were found on Moxostoma macrolepidotum (Shorthead Redhorse, Catostomidae) and Hybopsis amblops (Bigeye Chub, Cyprinidae) from the Meramec River, Missouri (Baird 2000, Williams et al. 2008).

The decline of the Spectaclecase in the Mississippi River system and overall declines of other mussel species in the eastern United States is primarily the result of habitat loss and degradation. These losses have been well documented since the mid-19th century (Higgins 1858). Chief among the causes of decline are impoundments, channelization, chemical contaminants, mining, and sedimentation (Williams et al. 1993, Neves 1993, Neves et al. 1997, Watters 2000). Less serious are the following: (1) the Spectaclecase is not a commercially valuable species, but may be increasingly sought by collectors as it becomes more rare; (2) disease or predation of which little is known may have greater impact on this species because it is particularly long-lived (Butler 2003); (3) invasive species (Asiatic Clam, Zebra Mussel, Black Carp). The immediacy of threats varies among Spectaclecase populations. Threats to some populations, such as those isolated and downstream of persistent coldwater releases, clearly have placed them in jeopardy of extirpation (i.e., threats are imminent and the likelihood of survival and recovery are marginal). Seven populations seem to be clearly unviable and another four may also be unviable due to isolation and a lack of recruitment (Butler 2003). Threats and risk of extirpation are clearly imminent for these eleven populations. On the other hand, ten populations are reproducing or may be supported via immigration from large, viable populations. Three or four of these populations may be described as large and viable, although each of these also faces serious threats. Populations in the Gasconade and Meramec Rivers of Missouri and perhaps also in the Upper Clinch River, Tennessee, are also large and viable. Although these are threatened in various ways, none of these threats currently seem to place them in imminent danger of extirpation. The Service should closely monitor and work to alleviate the immediacy of threats to these important Spectaclecase populations (see U.S. Fish and Wildlife Service, 2003).

The likelihood that some populations of the Spectaclecase are below the effective population size necessary to adapt to environmental change and persist in the long-term seems high. Many small Spectaclecase populations may be reproducing at levels too low to persist despite high adult survival. These populations may also be too isolated to be sustained by recruits from other populations. This species was widespread throughout much of the upper two-thirds of the Mississippi River system and in several tributary systems, and there were likely no or few natural barriers to prevent migration (via fish hosts) among suitable habitats. Construction of dams, primarily during the first half of the 20th century, destroyed Spectaclecase populations and isolated others (USFWS 2003).

This species is generally not utilized, though might become a target to collectors by becoming rare.

The recovery objectives for this species are: 1) Maintenance of high quality habitat, consisting of flowing water sites in medium-to-large rivers with good water quality (new national wildlife refuge on Clinch River planned; modified reservoir releases from some dams to improve water quality by Tennessee Valley Authority may allow for potential reintroduction). 2) Monitoring and regulating land use upstream to minimize erosion of silt to rivers. 3) Maintenance of ongoing conservation outreach program focused on the St. Croix River and its mussel fauna (including The St. Croix River Research Rendezvous group).

The St. Croix River population of the spectaclecase occurs within the St. Croix National Scenic Riverway, Minnesota and Wisconsin (SCNSR). Several state-owned properties (e.g., Chengwatana, Governor Knowles, St. Croix State Forests; Minnesota Interstate, St. Croix, St. Croix Wild River, William O'Brien, Wisconsin Interstate State Parks; St. Croix Islands Wildlife Area; Rock Creek Wildlife Management Area) lie adjacent to some sections of the SCNSR. The Upper Mississippi River National Wildlife and Fish Refuge manages scores of islands and shoreline acreage throughout a significant portion of the upper Mississippi. In-holdings of the refuge extend from the mouth of the Chippewa River downstream to Muscatine, Iowa. Between Muscatine and Keithsburgs, Illinois, the Mark Twain National Wildlife Refuge (MTNWR), Keithsburgs Division, has numerous in-holdings. A small disjunct portion of MTNWR, the Gardner Division, occurs in the Canton and La Grange, Missouri, area. Parts of the lower Big Piney River and significant reaches of the upper Gasconade River flow adjacent or through the Mark Twain National Forest; the lower Big Piney also flows through Ft. Leonard Wood Military Reservation. Small units of public land along the Meramec River include Meramec, Pacific Palisades, and River Round Conservation Areas, and Meramec, Onandaga Cave, and Robertsville State Parks. The Nature Conservancy (TNC) has created bioreserves along two stream systems harbouring extant populations of the Spectaclecase: the upper Clinch/Powell River, Tennessee and Virginia; and upper Green River, Kentucky. A small portion of the Clinch River watershed (e.g., several small tributaries) is located in the Jefferson National Forest. (see USFWS 2003).

This species is listed as Endangered by the American Fisheries Society (Williams et al. 2010). Further research regarding the taxonomy, population trends and ecology of this species is required.