Toxolasma pullus - (Conrad, 1838)
Savannah Lilliput
Other English Common Names: Savannah lilliput
Taxonomic Status: Accepted
Related ITIS Name(s): Toxolasma pullus (Conrad, 1838) (TSN 80367)
Unique Identifier: ELEMENT_GLOBAL.2.112404
Element Code: IMBIV43070
Informal Taxonomy: Animals, Invertebrates - Mollusks - Freshwater Mussels
 
Kingdom Phylum Class Order Family Genus
Animalia Mollusca Bivalvia Unionoida Unionidae Toxolasma
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: Toxolasma pullus
Taxonomic Comments: Toxolasma pullus from the lower Savannah River exhibit slightly different shell morphology: they have a more extensive beak sculpture than members of this species found elsewhere. They were once described as a separate species, Carunculina patrickae (Bates 1966), but C. patrickae was synonymized with C. pulla by Johnson (1970a) and is now known as T. pullus.
Conservation Status
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NatureServe Status

Global Status: G2
Global Status Last Reviewed: 15Dec2018
Global Status Last Changed: 06Mar2007
Ranking Methodology Used: Ranked by calculator
Rounded Global Status: G2 - Imperiled
Reasons: It may be limited to few reproducing populations. It is declining in many of the extant populations. Although widespread, occurrences are largely disjunct with very limited distributions and one change in the environment could cause a population to become extinct. Recent quantitative surveys indicate it represents only a few percent of the total individuals of all species of mussels present in the remaining river systems where it occurs. Some exceptions exist with good viability.
Nation: United States
National Status: N2 (06Mar2007)

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 Georgia (S2), North Carolina (S2), South Carolina (S1)

Other Statuses

IUCN Red List Category: VU - Vulnerable
American Fisheries Society Status: Threatened (01Jan1993)

NatureServe Global Conservation Status Factors

Range Extent: 20,000-200,000 square km (about 8000-80,000 square miles)
Range Extent Comments: This species is distributed from the Altamaha River Basin in Georgia to Neuse River Basin in North Carolina (Johnson 1970a) and includes the Savannah, Cooper-Santee, and Pee Dee River basins (Bogan et al., 2008). The Altamaha in Georgia represents the southern-most extant of the range of this species.

Area of Occupancy: 501-12,500 4-km2 grid cells
Area of Occupancy Comments: In North Carolina, it can be found in in Cape Fear, Lumber, and Yadkin-Pee Dee drainages (Chatham, Columbus, Lee, Montgomery, Moore, Orange, Randolph, Stanly, Union Cos.) (Ratcliffe, 2018), it is known currently from the Pee Dee River Basin in Union Co. (Crooked and Richardson creek subbasins), Montgomery Co. (Densons Creek Subbasin), and Randolph Co. (Little River Subbasin); as well as the Cape Fear River Basin in Orange Co. (University Lake). In South Carolina (Allendale, Calhoun, Clarendon, Orangeburg, Saluda Cos), it has been found in Lake Greenwood and Cloud?s Creek, both in the Saluda River basin, and in the Savannah River. Recently, a few individuals were found in Lake Marion in South Carolina, and three were found in the Ogeechee River in Georgia (Price 2005). In Georgia, the Savannah lilliput is known from the Savannah, Ogeechee, and Altamaha River systems (Bryan, Burke, Chatham, Jeff Davis, Long, Mcduffie, Richmond, Screven, Tattnall, Telfair, Warren, Wayne Cos.) occurring very sporadically (Wisniewski 2018).

Number of Occurrences: 21 - 80
Number of Occurrences Comments: Based on a survey by Alderman (1994) there are only seven extant populations of the Savannah lilliput: Ohoopee River in Georgia; Savannah River in South Carolina and Georgia; Richardson Creek (Rocky River basin), Densons Creek and Little River (Pee Dee River basin), Lake Waccamaw, and University Lake (Haw River basin) in North Carolina. Only three of these populations have shown any evidence of reproduction in the last several years. The only stable population in North Carolina is the University Lake population (Haw drainage) in Orange County (Hanlon and Levine 2004). Bogan (2002) cites the Pee Dee, Waccamaw (likely extirpated), Cape Fear, and Neuse River basins (possibly extirpated) in North Carolina in Columbus, Montgomery, Orange, Randolph, and Union Cos. (LeGrand et al. 2006). Bogan and Alderman (2004) list the South Carolina distribution as the Savannah, Cooper-Santee, and Pee Dee River basins. Alderman (2006) documented it in Lake Murray and tributaries in South Carolina. It is currently only reported in four locations in South Carolina primarily in the Saluda River basin (one as relict shells and not in the last 10 years except Lake Marion; others in Lake Greenwood and Cloud's Creek); and an extensive survey at the type locality (the Wateree River in South Carolina) in 2004 failed to find any surviving individuals (Jennifer Price, SC DNR, pers. comm., October 2005). Recently, specimens were collected from a single site in the Ogeechee River in Georgia; and it may still exist in the Altamaha (SC DNR, pers. comm., 2005).

Population Size: 100,000 - 1,000,000 individuals
Population Size Comments: This is a small mussel which may be easily found along stream, lake, or river banks in very localized areas. In fact, there may be many thousands of these mussels, but in very few locations. In 1999, this species was found to comprise 3.18% (relative abundance) of the 14873 mussels collected in surveys of 46 sites in 12 tributary streams of the lower Flint River Basin, Georgia (Gagnon et al., 2006). Only 7 individuals were found in Lake Marion in South Carolina and 3 in the Ogeechee River in Georgia in 2004 (J. Price, SC DNR, pers. comm., 2005).

Number of Occurrences with Good Viability/Integrity: Few (4-12)
Viability/Integrity Comments: The most viable surviving population of Savannah lilliput may be at University Lake in North Carolina; however, this population also appears to have exhibited recent declines (Taxonomic Expertise Committee 2004).

Overall Threat Impact Comments: Alderman (1994) has made a rather complete summary of the threats to each of the extant populations. The Ohoopee River population has declined along with several other species of mussels in the same part of the river. There are no readily identifiable threats. The Savannah River population extends over several miles, but this species seems to be located mainly in the old cutoffs and backwater areas. The U.S. Army Corps of Engineers has cut through many bends in the river, in effect to straighten the Savannah River for navigation. This dredging work seriously impacts the best populations in the world. The Clouds Creek and Asbill Pond population is very localized and any slight change in the flow, in the dam which forms the pond or siltation will easily wipe out this population. This population may also be seriously affected by eutrophication in Asbill Pond. The Richardson Creek population is very small. There are several threats to this population. Several road improvements have occurred on Richardson Creek, there is a wastewater treatment plant discharging in the stream, and the area is being developed. The Densons Creek and Little River populations are also very small. The Troy wastewater treatment plant outfall is between the Densons Creek and Little River populations. The Lake Waccamaw population was considered to be very low in 1979 and 1980 (Porter 1985). A North Carolina Wildlife Resources Commission survey in Lake Waccamaw failed to find any Savannah lilliputs in 1989. Declining water quality is the main threat. The University Lake population has been doing well, but could easily be threatened because it has such a limited distribution in the lake. It is very vulnerable to quick changes in water levels and compaction due to ATVs running along the banks of the waters. This species is also easy prey for raccoons which feed along the shoreline of various waterways. Predation is largest threat to the only remaining viable population in North Carolina at University Lake, Orange County (Hanlon and Levine 2004).

Short-term Trend: Decline of 30-70%
Short-term Trend Comments: The Ohoopee River population has declined along with several other species of mussels in the same part of the river. There are no readily identifiable threats (Aldermann, 1994). According to a survey made in 1996 (Keferl pers. obs. 1996) the Ohoopee River population was reproducing. However, specimens were hard to find. Of the seven extant populations described by Alderman (1994) only three showed any signs of reproduction. The other populations were declining and some may be gone by now (see also Hanlon and Levine, 2004). The species has been lost from the Neuse River basin in North Carolina (formerly in Neuse River in Wake Co.- Johnson 1970a) and likely from the Waccamaw basin as well (Bogan 2002).

Long-term Trend: Decline of 70-90%
Long-term Trend Comments: It is presently considered extirpated from the Neuse; and Waccamaw river basins (J. Aldermann, pers. comm., July 2002 in Bogan and Alderman 2008). In South Carolina, it has been lost from the Neuse basin and is declining rapidly throughout its range. The species was originally described from the Wateree River in South Carolina, but an extensive survey of this drainage in 2004 failed to find any surviving individuals (J. Alderman, pers. comm. in Price, 2005).

Intrinsic Vulnerability: Highly vulnerable
Intrinsic Vulnerability Comments: This species has very widely disjunct populations that are isolated from one another. The extremely low numbers of this species at so few sites make it particularly vulnerable; entire populations may be lost due to one smallscale event. The dispersal of this species appears to be limited by dams and old navigational structures in some locations (Taxonomic Expertise Committee 2004; Price 2005)

Environmental Specificity: Moderate. Generalist or community with some key requirements scarce.
Environmental Specificity Comments: The Savannah lilliput tends to inhabit shallow water, usually at the edges of streams, rivers and lakes; it may also be found in backwaters. This mussel is rarely found in deeper lake waters and it tends to be found in mud or silty sand. It will move up and down as the water levels flucuate (Bogan and Alderman 2004; Bogan 2002).

Other NatureServe Conservation Status Information

Inventory Needs: Inventory needs include: (1) Encourage more widespread sampling along shorelines of the many ponds, lakes and reservoirs, streams and rivers in Georgia, South Carolina and North Carolina; (2) Conduct additional surveys for the Savannah lilliput, especially in Lake Greenwood and Lake Marion, where the species has been reported, but population numbers not assessed; (3) Additional surveys are needed in areas where the savannah lilliput was historically found to determine if populations are extant.

Protection Needs: Protection needs include: (1) Investigate the need to list the Savannah lilliput as endangered in South Carolina, based on surveys and genetic investigations; (2) Closely monitor water levels and discourage shallow water activities at sites where the Savannah lilliput is found; (3) Investigate the potential for removing dams and old navigation structures that limit the dispersal of the Savannah lilliput. Alternatively, provide fish ladders (identity of fish host still unknown) or other methods allowing the potential dispersal of the mussel.

Protect critical habitats for the Savannah lilliput from future development and further habitat degradation by following best management practices and protecting and purchasing riparian areas; (4) Promote land stewardship practices through educational programs both within critical habitats with healthy populations and other areas that contain available habitat for the Savannah lilliput; (5) Encourage responsible land use planning; (6) Consider species needs when participating in the environmental permit review process; (7) Educate off-road motor vehicle operators of the negative affects of crossing streams at multiple locations and using stream bottoms as trails; (8) Conduct further research to determine the degree of sensitivity of the Savannah lilliput to various point and non-point source pollution sources and land use impacts.

Distribution
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Global Range: (20,000-200,000 square km (about 8000-80,000 square miles)) This species is distributed from the Altamaha River Basin in Georgia to Neuse River Basin in North Carolina (Johnson 1970a) and includes the Savannah, Cooper-Santee, and Pee Dee River basins (Bogan et al., 2008). The Altamaha in Georgia represents the southern-most extant of the range of this species.

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 GA, NC, SC

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
GA Bryan (13029), Burke (13033), Chatham (13051), Jeff Davis (13161), Long (13183), Mcduffie (13189), Richmond (13245), Screven (13251), Tattnall (13267), Telfair (13271), Warren (13301), Wayne (13305)
NC Chatham (37037), Columbus (37047), Lee (37105), Montgomery (37123), Moore (37125), Orange (37135), Randolph (37151), Stanly (37167), Union (37179)
SC Allendale (45005), Calhoun (45017), Clarendon (45027), Orangeburg (45075), Saluda (45081)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
03 Upper Neuse (03020201)*, Haw (03030002)+, Deep (03030003)+, Lower Yadkin (03040103)+, Upper Pee Dee (03040104)+, Rocky, North Carolina, (03040105)+, Waccamaw (03040206)+, Lower Catawba (03050103)*, Wateree (03050104)*, Saluda (03050109)+, Lake Marion (03050111)+, Middle Savannah (03060106)+, Brier (03060108)+, Lower Savannah (03060109)+, Upper Ogeechee (03060201), Lower Ogeechee (03060202)+, Lower Ocmulgee (03070104)+, Altamaha (03070106)+, Ohoopee (03070107)+
+ 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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Reproduction Comments: This species is a long-term brooder, brooding in August with hybrid bluegill (Lepomis macrochirus x Lepomis cyanellus) suitable as fish hosts (Hanlon and Levine 2004). Gravid females have been observed between late April through early August, but not during mid-September. Glochidia successfully transformed on hybrid sunfish (Lepomis sp.). Successful transformation likely occurs on other Lepomis species. Toxolasma pullus appears to be a long-term brooder, brooding into August. Hybrid bluegill (Lepomis macrochirus L. cyanellus) are suitable hosts for T. pullus, however, other Lepomis species may also serve as hosts. The sex ratio of the population was 1:1. Most specimens of T. pullus were between 4 and 6 years old; the oldest specimen was 9 years of age (Hanlon and Levine 2004).
Habitat Type: Freshwater
Non-Migrant: Y
Locally Migrant: N
Long Distance Migrant: N
Riverine Habitat(s): CREEK, Pool
Lacustrine Habitat(s): Shallow water
Special Habitat Factors: Benthic
Habitat Comments: The Savannah lilliput tends to inhabit shallow water, usually at the edges of streams (often very shallow), rivers and lakes; it may also be found in backwaters. This mussel is rarely found in deeper lake waters and it tends to be found in soft substrates like mud or silty sand. It will move up and down as the water levels fluctuate (Johnson 1970a; Bogan and Alderman 2004; Bogan 2002).
Adult Phenology: Circadian
Phenology Comments: Hanlon and Levine (2004) found oldest specimen to be 9 y.o.
Economic Attributes Not yet assessed
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Management Summary
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Stewardship Overview: Conduct additional surveys for the Savannah lilliput, especially in Lake Greenwood and Lake Marion, where the species has been reported, but population numbers not assessed. Additional surveys are needed in areas where the species was historically found to determine if populations are extant. Conduct genetic analysis across the range to determine if populations in the Savannah River described as Carunculina patrickae (Bates 1966), are genetically distinct from other populations and if they warrant classification as a separate species. Investigate the need to list the Savannah lilliput as endangered in the three state region, based on surveys and genetic investigations. Closely monitor water levels and discourage shallow water activities at sites where the species is found. Alternatively, provide fish ladders (identity of fish host still unknown) or other methods allowing the potential dispersal of the mussel. Work with other state agencies (DHEC) to determine appropriate minimum flows to protect the Savannah lilliput. Also, recommend minimum flows during the FERC relicensing process. Protect critical habitats from future development and further habitat degradation by following best management practices and protecting and purchasing riparian areas. Promote land stewardship practices through educational programs both within critical habitats with healthy populations and other areas that contain available habitat for the Savannah lilliput. Encourage responsible land use planning. Consider species needs when participating in the environmental permit review process. Educate off-road motor vehicle operators of the negative effects of crossing streams at multiple locations and using stream bottoms as trails. Conduct further research to determine the degree of sensitivity of the Savannah lilliput to various point and non-point source pollution sources and land use impacts.
Biological Research Needs: Research needs include: (1) Conduct genetic analysis across the range of the Savannah lilliput to determine if populations in the Savannah River described as Carunculina patrickae (Bates 1966), are genetically distinct from other populations and if they warrant classification as a separate species; (2) Investigate suitable host fish and life history information.
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: 15Dec2018
NatureServe Conservation Status Factors Author: Cordeiro, J.R.
Management Information Edition Date: 19Jan2019
Management Information Edition Author: Cordeiro, J.R.
Element Ecology & Life History Edition Date: 15Dec2018
Element Ecology & Life History Author(s): Cordeiro, J.R.

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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  • Adams, W.F., J.M. Alderman, R.G. Biggins, A.G. Gerberich, E.P. Keferl, H.J. Porter, and A.S. van Davender (eds.) 1990. A report on the conservation status of North Carolina's freshwater and terrestrial molluscan fauna. Report to NCWRC by Scientific Council on Freshwater and Terrestrial Mollusks. 246 pp.

  • Alderman, J. 1994. Status survey for the Savannah lilliput Toxolasma pullus (Conrad, 1838). U.S. Fish and Wildlife Service, Cooperative Agreement No. 14-16-004-89-954.

  • Bogan, A.E. and J.M. Alderman. 2004. Workbook and key to the freshwater bivalves of South Carolina. North Carolina Museum of Natural Sciences: Raleigh, North Carolina. 64 pp.

  • Bogan, A.E. and J.M. Alderman. 2008. Workbook and key to the freshwater bivalves of South Carolina. Revised second edition. North Carolina Museum of Natural Sciences: Raleigh, North Carolina. 66 pp.

  • Gagnon, P., W. Michener, M. Freeman, and J. Brim Box. 2006. Unionid habitat and assemblage composition in coastal plain tributaries of Flint River (Georgia). Southeastern Naturalist, 5(1): 31-52.

  • Hanlon, S.D. and J.F. Levine. 2004. Notes on the life history and demographics of the Savannah lilliput (Toxolasma pullus) (Bivalvia: Unionidae) in University Lake, NC. Southeastern Naturalist, 3(2): 289-296.

  • Hayes, G.F. and D.W. Taylor. 2006. Chorizanthe pungens var. pungens Endangered Species Fact Sheet. Elkhorn Slough Coastal Training Program. Online. Available: http://www.elkhornsloughctp.org/factsheet/factsheet.php?SPECIES_ID=37 (accessed 25 May 2009).

  • 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.

  • KEFERL, E.P. 1981. A SURVEY OF THE NAIADES OF THE OHOOPEE RIVER, GEORGIA. THE BULLETIN OF THE AMERICAN MALACOLOGICAL UNION, INC., 1981, PP. 11-15.

  • LeGrand, H.E., Jr., S.P. Hall, S.E. McRae, and J.T. Finnegan. 2006. Natural Heritage Program List of the Rare Animal Species of North Carolina. North Carolina Natural Heritage Program, Raleigh, North Carolina. 104 pp.

  • 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.

  • Porter, H. J. 1985. Rare and endangered fauna of Lake Waccamaw, North Carolina Watershed System. Molluscan census and ecological interrelationships. North Carolina Endangered Species Restoration Final Report to the North Carolina Wildlife Resouces Commission.

  • Ratcliffe, J. 2018. Natural Heritage Program List of Rare Animal Species of North Carolina. North Carolina Natural Heritage Program Report. 169 pp.

  • SEPKOSKI, J.J., AND M.A. REX. 1974. DISTRIBUTION OF FRESHWATER MUSSELS: COASTAL RIVERS AS BIOGEOGRAPHIC ISLANDS. SYST. ZOOL., 23(2):165-188.

  • South Carolina Department of Natural Resources (SCDNR). 2013. An Overview of the Eight Major River Basins of South Carolina. South Carolina Department of Natural Resources. 30 pp.

  • 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., 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.

  • 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., 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.

  • Wisniewski, J. 2018. Toxolasma pullus Species Fact Sheet. Georgia Department of Natural Resources, Wildlife Resources Division. 4 pp. Available: https://georgiabiodiversity.org/natels/profile.html?es_id=18950&fus_tab_id=1LVfJtQ01Mh9k6a9tCr4dsfqiFr9Fvh2sZW5WkJ3K&group=mollusk; Accessed 15 December 2018.

References for Watershed Distribution Map
  • Alderman, J. 2006. Reconnaissance survey of the freshwater mussel fauna of the Lower Saluda and Congaree Rivers, Lake Murray, and selected tributaries. Report prepared for Kleinschmidt Associates, West Columbia, South Carolina, 31 October 2006. 166 pp.

  • Bogan, A.E. 2002. Workbook and key to the freshwater bivalves of North Carolina. North Carolina Museum of Natural Sciences: Raleigh, North Carolina. 101 pp.

  • 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.

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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.

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