Medionidus simpsonianus - Walker, 1905
Ochlockonee Moccasinshell
Other English Common Names: Ochlockonee moccasinshell
Taxonomic Status: Accepted
Related ITIS Name(s): Medionidus simpsonianus Walker, 1905 (TSN 80267)
Unique Identifier: ELEMENT_GLOBAL.2.120661
Element Code: IMBIV28070
Informal Taxonomy: Animals, Invertebrates - Mollusks - Freshwater Mussels
 
Kingdom Phylum Class Order Family Genus
Animalia Mollusca Bivalvia Unionoida Unionidae Medionidus
Genus Size: C - Small genus (6-20 species)
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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: Medionidus simpsonianus
Taxonomic Comments: Clench and Turner (1956) recognized only one species of Medionidus from the Suwannee, Ochlockonee, and Apalachicola River systems. Their records of Medionidus penicillatus from the Ochlockonee River are now recognized as Medionidus simpsonianus, and their Suwannee River records are now recognized as Medionidus walkeri (Johnson, 1977).
Conservation Status
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NatureServe Status

Global Status: G1
Global Status Last Reviewed: 14Jan2014
Global Status Last Changed: 31Aug2000
Rounded Global Status: G1 - Critically Imperiled
Reasons: The species is restricted to only one moderately small river system, with only two mainstem sites documented in recent decades (believed to be extirpated at six of the seven known historical sites).
Nation: United States
National Status: N1 (31Aug2000)

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 Florida (S1), Georgia (SH)

Other Statuses

U.S. Endangered Species Act (USESA): LE: Listed endangered (16Mar1998)
U.S. Fish & Wildlife Service Lead Region: R4 - Southeast
IUCN Red List Category: CR - Critically endangered
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: The species is restricted to a single river system, the Ochlockonee River in Panhandle Florida (Leon and Gadsden counties) and adjacent southern Georgia (Grady and Thomas counties (USFWS, 2003). The species is historically known from 21 collections from seven localities, six of which are on ther river main stem (Johnson, 1977). Based on a recent survey, it appears to be extirpated from the single site from a tributary stream, the Little River in Florida. In 1993, all of the historical occurrences were resurveyed, as well as 66 new sites (J. Brim Box, pers. obs.), and it was found at two of the historical sites.

Area of Occupancy: 1-25 4-km2 grid cells
Area of Occupancy Comments: It is uncertain whether any populations of the Ochlockonee moccasinshell persist. Occupancy estimates are based on fewer than five individuals collected since 1973. Linear occupancy is <4 km.

Number of Occurrences: 1 - 5
Number of Occurrences Comments: It is restricted to a single river system, the Ochlockonee River in Panhandle Florida and adjacent southern Georgia (Grady and Thomas counties). Within this system, it is extant only in the main channel and not tributaries (USFWS, 2003).

Population Size: 1 - 250 individuals
Population Size Comments: Of the 21 historical records known, only two contain more than 20 specimens (i.e., 21 and 24). A comprehensive survey of the Ochlockonee River system in 1993 yielded only one live animal and one shell, although approximately six more individuals have been collected since 1993. This species is one of the rarest eastern Gulf slope unionids.

Number of Occurrences with Good Viability/Integrity: None (zero)
Viability/Integrity Comments: No sites with good viability (Butler and Alam, 1999). Only three live specimens are known to have been collected since 1974 despite repeated search efforts (USFWS, 2003).

Overall Threat Impact: Very high - high
Overall Threat Impact Comments: This species is highly restricted in distribution, occurs in generally small subpopulations, and shows little evidence of recovering from historical habitat losses without significant positive human intervention. Principal causes of decline include impoundments, channelization, pollution, and sedimentation that have altered or eliminated those habitats that are essential to the long-term viability of many riverine mussel populations. Detailed information on these threats can be found in USFWS (2003) and include: (1) exploitation by native Americans and for pearls and pearl buttons plus overcollection for scientific purposes (very localized, low impact, historical only), (2) habitat alteration- impoundment causing loss of habitat, loss of shoal habitat, thermal alterations, daily discharge fluctuations, bank sloughing, seasonal oxygen deficiencies, coldwater releases, turbulence, high silt loads, and altered host fish distribution (widespread, high impact, ongoing); (3) impoundment- channelization for navigation and maintenance causing sedimentation and contamination (moderate scope, high impact, historical and ongoing); (4) habitat alteration- gravel mining causing riparian forest clearing, channel modification, disrupted flow, water quality modification, impacts on host fish populations, substrate disturbance/siltation, pollution (moderate scope, high impact, historical and ongoing); (5) contaminants- heavy metals, arsenic and ammonia from poultry and animal feedlots, industrial/municipal effluent, agricultural nutrient enrichment from poultry farms and livestock feedlots, herbicides/pesticides, nutrients from aquaculture ponds, urban stormwater runoff, municipal waste discharge (high-moderate scope, high impact, historical and ongoing); (6) sedimentation- from agricultural, silvicultural, and roadway activities, clearing of riparian vegetation, and flood control activities, gravel mining, livestock grazing (high-moderate scope, high impact, historical and ongoing); (7) urbanization- highways, infrastructure, recreational activities (low scope, moderate-low impact, historical and ongoing); (8) "deadhead logging"- disruption of habitat, increased sediment (localized in Florida only, moderate impact, potential future threat); (9) water withdrawel- mostly for irrigation (moderate impact, moderate scope, ongoing); (10) introduced species- Asiatic clam, zebra mussel, black carp (moderate-low scope, moderate impact, ongoing). Many of the impacts discussed in USFWS (2003) occurred in the past as unintended consequences of human development in the Apalachicolan Region. However, the species and its habitats continue to be impacted by excessive sediment bed loads of smaller sediment particles, changes in turbidity, increased suspended solids (primarily resulting from nonpoint-source loading from poor land-use practices, lack of BMPs, and maintenance of existing BMPs), and pesticides. Siltation from various sources, including poorly conducted agricultural and silvicultural activities (particularly in the Little River system); agricultural and silvicultural runoff, chicken farm litter nutrients (?); Localized municipal and residential pollution; watershed development (e.g., bridges, highways); competition from Asiatic clam (CORBICULA) is a possibility, due to the great density of CORBICULA at upper Ochlockonee sites. Overharvest by shell collectors and biologists may have contributed to already stressed populations, at least in the 1960's and 1970's. The creation of Talquin Reservoir destroyed much riverine habitat, including probably the once productive occurrence at the upstream end of the reservoir.

Short-term Trend: Decline of >70%
Short-term Trend Comments: This species is apparently declining, like most regional endemics. Drastic population declines have occurred at all of the historical localities, and it appears to be extirpated from five of them. This species is now known from two sites (at most) on the Ochlockonee River mainstem. Only three live individuals have been found since 1974 (Butler and Alam, 1999).

Long-term Trend: Decline of >90%
Long-term Trend Comments: Long-term decline of nearly 100% of former historic occurrences (possibly one extant subpopulation) has occurred (USFWS, 2003).

Intrinsic Vulnerability: Highly vulnerable
Intrinsic Vulnerability Comments: Freshwater mussels are inherently vulnerable to threats from siltation, pollution, eutrophication, channelization, impoundment, collection, drought and water withdrawal, competiton from invasive non-native mussels, and changes to larval host fish populations. This diminutive species is probably highly sensitive to sedimentation and habitat modifications. The species has been reduced to a point where recruitment and dispersal are severely hindered.

Environmental Specificity: Narrow. Specialist or community with key requirements common.

Other NatureServe Conservation Status Information

Inventory Needs: Resurvey selected sites of the main stem of the Ochlockonee River for evidence of presence and recruitment (i.e., the presence of juvenile mussels).

Protection Needs: Maintain high water and benthic habitat (substrate) qualities, as well as adequate flow regimes, throughout the Ochlockonee River system. This may be partially accomplished via establishment of buffers and streamside management zones for all agricultural, silvicultural, mining, and developmental activities; protection of floodplain forests and adjoining upland habitat is paramount. Best management practices to follow include employing forestry practices that cause minimal soil erosion; preventing access of livestock to natural surface waters and drains; situating roads at least 0.25 mi. (0.4 km) from heads of all tributaries, even more on steep slopes; using silt fencing and vegetation to control runoff and siltation at all stream crossings, especially during construction and maintenance; using and maintaining sewer systems rather than septic tanks and stream-dumping for management of wastewater; and avoiding use of agricultural pesticides on porous soils near streams. Prevent damming, dredging, and pollution throughout drainages, but especially near recorded sites. Remove existing dams, but with great care to limit downstream sedimentation. Limit withdrawal of surface and subterranean waters as necessary to maintain normal stream flows, especially during drought. Prevent or limit establishment of invasive species (including zebra mussel, Dreissena polymorpha) to the extent possible. Where appropriate, protect populations through acquisitions and easements over streamside lands by working with government agencies and conservation organizations. If found alive, facilitate prompt emergency federal listing as an endangered species.
Also, consider propagation for future reintroduction. For more, see detailed recovery plan (Butler et al., 2003).

Distribution
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Global Range: (<100 square km (less than about 40 square miles)) The species is restricted to a single river system, the Ochlockonee River in Panhandle Florida (Leon and Gadsden counties) and adjacent southern Georgia (Grady and Thomas counties (USFWS, 2003). The species is historically known from 21 collections from seven localities, six of which are on ther river main stem (Johnson, 1977). Based on a recent survey, it appears to be extirpated from the single site from a tributary stream, the Little River in Florida. In 1993, all of the historical occurrences were resurveyed, as well as 66 new sites (J. Brim Box, pers. obs.), and it was found at two of the historical sites.

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 FL, GA

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
FL Gadsden (12039)*, Leon (12073)*, Liberty (12077)*, Wakulla (12129)*
GA Grady (13131)*
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
03 Upper Ochlockonee (03120002), Lower Ochlockonee (03120003)+, New (03130013)+*
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
U.S. Distribution by Watershed (based on multiple information sources) Help
Ecology & Life History
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Basic Description: A small, elongate, sculptured freshwater mussel.
General Description: See Johnson (1977) and Deyrup and Franz (1994). This species is slightly elongate-elliptical in outline, the posterior end obtusely rounded at the shell's median line and the ventral margin broadly curved. The posterior ridge is moderately angular and covered in its entire length with well developed, irregular ridges. Sculpture may also extend onto the disk below the ridge. Surface texture is smooth. Color is light brown to yellowish green, with dark green rays formed by a series of connected chevrons or undulating lines across the length of the shell. Lateral teeth are thin and straight and pseudocardinal teeth are compressed. There are two laterals and two pseudocardinals in the left valve and one lateral and one pseudocardinal tooth in the right valve. Nacre is bluish white (Butler and Alam, 1999).
Diagnostic Characteristics: Unique outline with ventral margin broadly curved, posterior point medial in position, dark shell with dark green rays forming chevrons, some sculpture on posterior slope.
Reproduction Comments: Life history unknown due to extreme rarity and the glochidial host is not known (Butler and Alam, 1999; USFWS, 2003).
Ecology Comments: A high habitat quality species of stream channels. Probably was always uncommon, as may be the host fish (fishes).
Habitat Type: Freshwater
Non-Migrant: N
Locally Migrant: N
Long Distance Migrant: N
Mobility and Migration Comments: Greatest potential during glochidial stage on fish. Adults of this species are essentially sessile however some passive movement downstream may occur during high flows.
Riverine Habitat(s): CREEK, Low gradient, MEDIUM RIVER, Riffle
Special Habitat Factors: Benthic
Habitat Comments: It has been reported from muddy sand and sand in moderate current (Heard, 1979), and from sand and gravel substrates in moderate current (Deyrup and Franz, 1994). Deyrup and Franz (1994) also reported it from large creeks, although the basis for that observation is not clear, since there is only one historical record of this species from a tributary stream. In recent surveys it was found in large creeks of the Ochlockonee River main stem in areas with current in sandy substrates with some light gravel in mid-channel areas (J. Brim Box, pers. obs.; USFWS, 2003).
Adult Food Habits: Detritivore
Immature Food Habits: Parasitic
Food Comments: Presumably fine particulate organic matter, primarily detritus, and/or zooplankton, and/or phytoplankton (Fuller, 1974). Larvae (glochidia) of freshwater mussels are generally parasitic on fish and there may be a specificity among some species.
Length: 4.4 centimeters
Economic Attributes Not yet assessed
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Management Summary
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Stewardship Overview: This species was added to the U.S. federal endangered species list in 1998 (USFWS, 1998). A recovery plan was created for this species (USFWS, 2003).

The recovery plan (USFWS. 2003) outlines the following objectives for recovery: (1) preserve extant subpopulations and currently occupied habitats and ensure subpopulation viability, (2) search for additional subpopulations of the species and suitable habitat, (3) determine through research and propagation technology the feasibility of augmenting extant subpopulations and reintroducing the species into historical habitat, (4) evaluate efforts and monitor subpopulation levels and habitat conditions of existing subpopulations, as well as newly discovered, introduced, or expanding subpopulations, (5) develop and implement cryogenic techniques to preserve genetic material until such time as conditions are suitable for reintroduction, (6) develop and utilize a public outreach and environmental education program, (7) assess the overall success of the recovery program and recommend actions (e.g., changes in recovery objectives, delist, implement new measures, conduct additional studies).


Critical habitat has been designated for 177.3 km of the Upper Ochlockonee River, Florida and Georgia (USFWS, 2006).

Biological Research Needs: Host fish identification. Based on other Medionidus spp., the host fish is probably a species of darter, but research is needed to confirm this speculation. Determine viability of extant populations (if any), microhabitat requirements, and sensitivity to excess sedimentation and chemical pollution.
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: 14Jan2014
NatureServe Conservation Status Factors Author: Jackson, D. R. (2014); Cordeiro, J. (2007)
Element Ecology & Life History Edition Date: 13Feb2007
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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  • BUTLER, ROBERT S. 1993. RESULTS OF A STATUS SURVEY FOR EIGHT FRESHWATER MUSSELS ENDEMIC TO EASTERN GULF SLOPE DRAINAGES OF THE APALACHICOLAN REGION OF SOUTHEAST ALABAMA, SOUTHWEST GEORGIA, AND NORTH FLORIDA. USFWS RPT. 30PP + MAPS, FIGS.

  • Burch, J.B. 1975c. Freshwater Unionacean Clams (Mollusca: Pelecypoda) of North America: Biota of Freshwater Ecosystems, Identification Manual No 11. Environmental Protection Agency, Washington, D.C. 176 pp.

  • Clench, W.J. and R.D. Turner. 1956. Freshwater mollusks of Alabama, Georgia, and Florida from the Escambia to the Suwanee River. Bulletin of the Florida State Museum Biological Sciences, 1(3): 97-239.

  • Clench, William J., and Ruth D. Turner. 1956. Freshwater mollusks of Alabama, Georgia, and Florida from the Escambia to the Suwanee River. Bulletin of the Florida State Museum Biological Sciences. I(3):180-181.

  • Deyrup, M. and R. Franz. 1994. Rare and Endangered Biota of Florida, Volume IV. Invertebrates. University Press of Florida: Gainesville, Florida. 798 pp.

  • Deyrup, M., and R. Franz. 1994. Rare and Endangered Biota of Florida, Volume IV: Invertebrates. University Press of Florida, Gainesville. 798 pp.

  • Fuller, S.L.H. 1974. Chapter 8: Clams and mussels (Mollusca: Bivalvia). Pages 215-273 in: C.W. Hart, Jr. and S.L.H. Fuller (eds.) Pollution Ecology of Freshwater Invertebrates. Academic Press: New York. 389 pp.

  • Heard, W.H. 1979. Identification manual of the fresh water clams of Florida. State of Florida, Department of Environmental Regulation, Technical Series, 4(2): 1-82.

  • Howard, A.D. 1915. Some exceptional cases of breeding among the Unionidae. The Nautilus 29:4-11.

  • JOHNSON, R.I. 1970. THE SYSTEMATICS AND ZOOGEOGRAPHY OF THE UNIONIDAE OF THE SOUTHERN ATLANTIC SLOPE REGION. BULL. MUS. COMP. ZOOL., HARVARD UNIV., CAMBRIDGE, MA. 140(6):263-450.

  • Johnson, R.I. 1970a. The systematics and zoogeography of the Unionidae (Mollusca: Bivalvia) of the southern Atlantic slope region. Bulletin of the Museum of Comparative Zoology, Harvard University 140(6): 263-449.

  • Johnson, R.I. 1977. Monograph of the genus Medionidus (Bivalvia: Unionidae) mostly from the Apalachicolan region, southeastern United States. Occasional Papers on Mollusks, 4(56): 161-187.

  • Lefevre, G. and W.T. Curtis. 1912. Studies on the reproduction and artificial propogation of fresh-water mussels. Bulletin of the Bureau of Fisheries 30:102-201.

  • Moyle, P. and J. Bacon. 1969. Distribution and abundance of molluscs in a fresh water environment. Journal of the Minnesota Academy of Science 35(2/3):82-85.

  • Strayer, D. 1983. The effects of surface geology and stream size on freshwater mussel (Bivalvia, Unionidae) distribution in southeastern Michigan, U.S.A. Freshwater Biology 13:253-264.

  • Strayer, D.L. 1999a. Use of flow refuges by unionid mussels in rivers. Journal of the North American Benthological Society 18(4):468-476.

  • Strayer, D.L. and J. Ralley. 1993. Microhabitat use by an assemblage of stream-dwelling unionaceans (Bivalvia) including two rare species of Alasmidonta. Journal of the North American Benthological Society 12(3):247-258.

  • Turgeon, D.D., A.E. Bogan, E.V. Coan, W.K. Emerson, W.G. Lyons, W.L. Pratt, C.F.E. Roper, A. Scheltema, F.G. Thompson, and J.D. Williams. 1988. Common and scientific names of aquatic invertebrates from the United States and Canada: mollusks. American Fisheries Society Special Publication 16: viii + 277 pp., 12 pls.

  • 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) (Butler, R.S., J. Ziewitz, S.K. Alam, and H.N. Blalock-Herod). 2003. Agency draft recovery plan for endangered fat threeridge (Amblema neislerii), shinyrayed pocketbook (Lampsilis subangulata), gulf moccasinshell (Medionidus penicillatus), ochlockonee moccasinshell (Medionidus simpsonianus), oval pigtoe (Pleurobema pyriforme) and threatened chipola slabshell (Elliptio chipolaensis), and purple bankclimber (Elliptoideus sloatianus). United States Fish and Widllife Service, Atlanta, Georgia. 144 pp.

  • U.S. Fish and Wildlife Service (USFWS). 1999. Technical/agency draft recovery plan for endangered fat threeridge (Amblema neislerii), shinyrayed pocketbook (Lampsilis subangulata), gulf moccasinshell (Medionidus penicillatus), ochlockonee moccasinshell (Medionidus penicillatus), oval pigtoe (Pleurobema pyriforme), and purple bankclimber (Elliptoideus sloatianus) and threatened chipola slabshell (Elliptio chipolaensis), and purple bankclimber (Elliptoideus sloatianus). U.S. Fish and Wildlife Service: Atlanta, Georgia. 106 pp.

  • U.S. Fish and Wildlife Service (USFWS). 2003. Recovery plan for endangered fat threeridge (Amblema neislerii), shinyrayed pocketbook (Lampsilis subangulata), gulf moccasinshell (Medionidus penicillatus), Ochlockonee moccasinshell (Medionidus simpsonianus), and oval pigtoe (Pleurobema pyriforme); and threatened chipola slapshell (Elliptio chipolaensis), and purple bankclimber (Elliptoideus sloatianus). U.S. Fish and Wildlife Service, Atlanta, Georgia. 142 pp.

  • U.S. Fish and Wildlife Service (USFWS). 2006. Endangered and Threatned Wildlife and Plants; Critical Habitat for five endangered and two threatened mussels in four northeast Gulf of Mexico drainages; proposed rule. Federal Register, 71(108): 32746-32795.

  • Van der Schalie, H. 1938a. The naiad fauna of the Huron River in southeastern Michigan. Miscellaneous Publication of the Museum of Zoology, University of Michigan 40:7-78.

  • Watters, G.T. 1992a. Unionids, fishes, and the species-area curve. Journal of Biogeography 19:481-490.

  • Williams, J. D., A. E. Bogan, R. S. Butler, K. S. Cummings, J. T. Garner, J. L. Harris, N. A. Johnson, and G. T. Watters. 2017. A revised list of the freshwater mussels (Mollusca: Bivalvia: Unionida) of the United States and Canada. Freshwater Mollusk Biology and Conservation 20:33-58.

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

  • Williams, J. D., R. S. Butler, G. L. Warren, and N. A. Johnson.  2014.  Freshwater Mussels of Florida.  University of Alabama Press, Tuscaloosa.  498 pp.

  • Williams, J.D. and R.S. Butler. 1994. Freshwater mussels. Vol. 6, Invertebrates. R Frantz, ed. Rare and endangered biota of Florida. FL Committee on Rare and Endangered Plants and Animals, Univ. Presses of FL.

  • 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.

  • Williams, James, D., Robert S. Butler, Gary L. Warren, Nathan A. Johnson. 2014. Freshwater Mussels of Florida. University of Alabama Press, Sep 30, 2014

  • van der Schalie, H. 1940. The naiad fauna of the Chipola River in northwestern Florida. Lloydia 3(3):191-208.

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Note: All species and ecological community data presented in NatureServe Explorer at http://explorer.natureserve.org were updated to be current with NatureServe's central databases as of March 2019.
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Citation for data on website including State Distribution, Watershed, and Reptile Range maps:
NatureServe. 2019. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available http://explorer.natureserve.org. (Accessed:

Citation for Bird Range Maps of North America:
Ridgely, R.S., T.F. Allnutt, T. Brooks, D.K. McNicol, D.W. Mehlman, B.E. Young, and J.R. Zook. 2003. Digital Distribution Maps of the Birds of the Western Hemisphere, version 1.0. NatureServe, Arlington, Virginia, USA.

Acknowledgement Statement for Bird Range Maps of North America:
"Data provided by NatureServe in collaboration with Robert Ridgely, James Zook, The Nature Conservancy - Migratory Bird Program, Conservation International - CABS, World Wildlife Fund - US, and Environment Canada - WILDSPACE."

Citation for Mammal Range Maps of North America:
Patterson, B.D., G. Ceballos, W. Sechrest, M.F. Tognelli, T. Brooks, L. Luna, P. Ortega, I. Salazar, and B.E. Young. 2003. Digital Distribution Maps of the Mammals of the Western Hemisphere, version 1.0. NatureServe, Arlington, Virginia, USA.

Acknowledgement Statement for Mammal Range Maps of North America:
"Data provided by NatureServe in collaboration with Bruce Patterson, Wes Sechrest, Marcelo Tognelli, Gerardo Ceballos, The Nature Conservancy-Migratory Bird Program, Conservation International-CABS, World Wildlife Fund-US, and Environment Canada-WILDSPACE."

Citation for Amphibian Range Maps of the Western Hemisphere:
IUCN, Conservation International, and NatureServe. 2004. Global Amphibian Assessment. IUCN, Conservation International, and NatureServe, Washington, DC and Arlington, Virginia, USA.

Acknowledgement Statement for Amphibian Range Maps of the Western Hemisphere:
"Data developed as part of the Global Amphibian Assessment and provided by IUCN-World Conservation Union, Conservation International and NatureServe."

NOTE: Full metadata for the Bird Range Maps of North America is available at:
http://www.natureserve.org/library/birdDistributionmapsmetadatav1.pdf.

Full metadata for the Mammal Range Maps of North America is available at:
http://www.natureserve.org/library/mammalsDistributionmetadatav1.pdf.

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