Strophitus undulatus - (Say, 1817)
Other English Common Names: Squawfoot
Taxonomic Status: Accepted
Related ITIS Name(s): Strophitus undulatus tennesseensis Frierson (TSN 80153) ;Strophitus undulatus undulatus (Say, 1817) (TSN 80152) ;Strophitus undulatus (Say, 1817) (TSN 80151)
French Common Names: strophite nodule
Unique Identifier: ELEMENT_GLOBAL.2.107752
Element Code: IMBIV42030
Informal Taxonomy: Animals, Invertebrates - Mollusks - Freshwater Mussels
Kingdom Phylum Class Order Family Genus
Animalia Mollusca Bivalvia Unionoida Unionidae Strophitus
Genus Size: A - Monotypic genus
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Concept Reference
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: Strophitus undulatus
Taxonomic Comments: The taxonomic status of Strophitus in western Gulf Coast drainages is unclear as Strecker (1931) reported S. subvexus from eastern Texas but Howells et al. (1996) considered all individuals in the state to be S. undulatus. Meanwhile, Vidrine (1993) suggested that Strophitus from western Louisiana (i.e., those in the Calcasieu and Sabine Rivers) represent an undescribed species similar to S. subvexus. Williams et al. (2008) confined S. subvexus to the Tombigbee and Black Warrior River drainages and S. connasaugensis to eastern drainages of the Mobile Basin, however individuals resembling S. subvexus can sometimes be found in eastern reaches of the Mobile basin and individuals resembling S. connasaugaensis can occasionally be found in the Black Warrior and Tombigbee River drainages.
Conservation Status

NatureServe Status

Global Status: G5
Global Status Last Reviewed: 01Aug2017
Global Status Last Changed: 25Nov1996
Ranking Methodology Used: Ranked by inspection
Rounded Global Status: G5 - Secure
Reasons: The species is extremely wide ranging being one of the few North American mussels to occur on both sides of the Appalachian Mountains. It is distributed throughout the Mississippi River and Great Lakes systems, northern Atlantic Coast drainages, and parts of Canadian Interior Basin. Presumably, it occurred throughout the Tennessee River system historically. In Alabama, it reaches its southern limit in a short reach of Bear Creek, Colbert Co., where it may not be viable, otherwise it is considered stable throughout its wide range.
Nation: United States
National Status: N5 (16Jul1998)
Nation: Canada
National Status: N5 (01Aug2017)

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 Alabama (S1), Arkansas (S3), Colorado (SNR), Connecticut (SU), Delaware (S1), District of Columbia (SNR), Georgia (SNR), Illinois (S4), Indiana (S4), Iowa (S2), Kansas (S2), Kentucky (S4S5), Louisiana (S2), Maine (SNR), Maryland (S2), Massachusetts (S3), Michigan (SNR), Minnesota (SNR), Mississippi (S1), Missouri (S4), Nebraska (SNR), New Hampshire (S3S4), New Jersey (S3), New York (S4), North Carolina (S3), North Dakota (SNR), Ohio (S5), Oklahoma (S3), Pennsylvania (S5), Rhode Island (S1), South Carolina (S2), South Dakota (S3), Tennessee (S5), Texas (S1), Vermont (S3), Virginia (S3S4), West Virginia (S3), Wisconsin (S4)
Canada Manitoba (S5), New Brunswick (SU), Nova Scotia (S1), Ontario (S5), Quebec (S3), Saskatchewan (SU)

Other Statuses

American Fisheries Society Status: Currently Stable (01Jan1993)

NatureServe Global Conservation Status Factors

Range Extent: >2,500,000 square km (greater than 1,000,000 square miles)
Range Extent Comments: The creeper is distributed very widely throughout the Ohio and Mississippi Rivers and Great Lakes systems, northern Atlantic Coast drainages, and parts of Canadian Interior Basin as far west as Texas and Saskatchewan (Burch, 1975; Parmalee and Bogan, 1998) and historically into Kansas and Nebraska (Hoke, 2005). Presumably, it occurred throughout the Tennessee River system historically. Colorado reports are in error/unconfirmed (Wu, 1989; Cordeiro, 1999; Clarke et al., 2003).

Area of Occupancy: >12,500 4-km2 grid cells
Area of Occupancy Comments:  

Number of Occurrences: > 300
Number of Occurrences Comments: In Alabama, it is only in Bear Creek (Colbert Co.) (Mirarchi et al., 2004; Williams et al., 2008). Tennessee (statewide): upper Clinch, Powell, Watauga, Little, Elk, Big S Fork Cumberland, Stones, Harpeth to Hatchie and W (Parmalee and Bogan, 1998). In Kentucky, Green River E (Cicerello and Schuster, 2003). In Mississippi: Mississippi River S, Yazoo, and Tennessee basins (Jones et al., 2005). It is in the White (rare) (Gordon, 1982; Christian, 1995), lower Arkansas (Gordon, 1985), Ouachita (Posey et al., 1996; Posey, 1997), and Poteau (Vaughn and Spooner, 2004), Arkansas. It is in all Illinois drainages (Cummings and Mayer, 1997; Schanzle and Cummings, 1991; Sietman et al., 2001; Schanzle et al., 2004; Tiemann et al., 2005). In Indiana: E. Fork White (Harmon, 1992), Muscatatuck (Harmon, 1989); Tippecanoe (Cummings and Berlocher, 1990). It is throughout Ohio (Watters, 1995; Lyons et al., 2007; Grabarciewicz, 2008; Hoggarth et al., 2007; Watters et al., 2009). In Louisiana, it is in the N (Cypress Creek, Bayou D'Arbonne, Tensas, Little Corney Bayou, Dugdemona, Sabine, Bayou Pierre) (Vidrine, 1993). In West Virginia: Upper Ohio (Zeto et al., 1987), Upper Potomac (Clayton et al., 2001; Taylor, 1985). In Maryland, it is in the Upper Potomac, Washington Metro, Chester, Choptank drainages (Bogan and Proch, 1995); lower Susquehanna (Ashton, 2009). In Maine, it is uncommon in most basins (absent from Knox, Lincoln, York Cos.) (Nedeau et al., 2000). In Rhode Island, it is in the middle to S (Raithel and Hartenstein, 2006). In Vermont, it is widely distributed; rarely common (Fichtel and Smith, 1995). Connecticut: Connecticut, Housatonic, Thames drainages (Nedeau and Victoria, 2003; J. Cordeiro, pers. obs., 2006). Massachusetts: most drainages (uncommon exc. Connecticut tribs.) (Smith, 2000). In the Delaware basin, it is in all drainages (Middle Delaware- Mongaup- Broadhead, Upper Delaware, E Branch Delaware); New York to Pennsylvania (Strayer and Ralley, 1991). In Minnesota, it is abundant statewide (Sietman, 2003); Red and Lake of the Woods; not Lake Superior (Graf, 1997; Cvancara, 1970). In South Carolina, it is widespead in the Savannah, Cooper-Santee, and Pee Dee basins (Bogan and Alderman, 2004); Great Pee Dee (Catena Group, 2006); Santee (Alderman, 2006). In South Dakota, it is in the Minnesota, Big Sioux (Skadsen and Perkins, 2000), Lake Kampeska, Vermillion (Backlund, 2000), and James (Perkins and Backlund, 2003). In North Carolina, it is widespread in Atlantic slope (Broad, Pee Dee, Cape Fear, Neuse, Pamlico, Roanoke); French Broad (Tennessee basin) (Bogan, 2002; LeGrand et al., 2006- 36 Cos.). Oklahoma: Illinois, Kiamichi, Neosho, Poteau, Clear Boggy Rivers (Branson, 1983); Mountain Fork (Spooner and Vaughn, 2007), Little and Red Rivers (Vaughn and Taylor, 1999; Vaughn, 2000). In Texas, from Guadalupe drainage N and E (Howells et al., 1996) and Cypress Bayou NE (Mather and Bergmann, 1994). In Wisconsin, it is widespread and abundant (Mathiak, 1997). In Kansas, it is in the Neosho, Verdigris, Spring, and Marais des Cygnes basins; historical in Wakarusa (Tiemann, 2006), Ninnescah (AR), Smoky Hill to lower Republican (KS), and S Fork Big Nemaha (MO) (Couch, 1997). In the Little Blue, weathered in Kansas/Nebraska (Hoke, 2004); common in Kansas part of Big Blue (most weathered); and in Big Hemana (E) (Hoke, 2005); also Platte (Hall, Buffalo Cos.) and Niobrara (Sioux Co.) (Freeman and Perkins, 1992; 1997). It is in the Clinton drainage, Michigan (Strayer, 1980; Goodrich and Van der Schalie, 1939) and Lakes Michigan, Huron, St. Clair drainages (Badra and Goforth, 2003). In Canada, it is widespread/abundant in Ontario; sensitive in Manitoba (Assiniboine drainage- Watson, 2000; Pip, 2006) and Quebec, at risk in Nova Scotia (Cumberland, Cape Breton Cos.) (Athearn and Clarke, 1962; Clarke and Rick, 1964); and information lacking on Saskatchewan and New Brunswick (Shediac River- Athearn, 1961) (Metcalfe-Smith and Cudmore-Vokey, 2004).

Population Size: >1,000,000 individuals
Population Size Comments: This species was recently collected in the Opequon River (Potomac watershed) in West Virginia (Vila et al., 2003). Smith and Crabtree (2010) found this species at 8 of 32 sites (unknown how many with recruitment) along the entire length of Pennsylvania's French Creek.

Number of Occurrences with Good Viability/Integrity: Very many (>125)

Short-term Trend: Relatively Stable (<=10% change)
Short-term Trend Comments: This species is extremely rare or extirpated from the North Fork Holston River, Virginia (Jones and Neves, 2007).

Long-term Trend: Decline of <30% to increase of 25%
Long-term Trend Comments: It is historically known from the Upper Clinch River, Virginia (Jones et al., 2001).

Intrinsic Vulnerability: Not intrinsically vulnerable
Intrinsic Vulnerability Comments: Widespread, though not usually common; generalist.

Environmental Specificity: Broad. Generalist or community with all key requirements common.
Environmental Specificity Comments: Habitat generalist.

Other NatureServe Conservation Status Information

Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) The creeper is distributed very widely throughout the Ohio and Mississippi Rivers and Great Lakes systems, northern Atlantic Coast drainages, and parts of Canadian Interior Basin as far west as Texas and Saskatchewan (Burch, 1975; Parmalee and Bogan, 1998) and historically into Kansas and Nebraska (Hoke, 2005). Presumably, it occurred throughout the Tennessee River system historically. Colorado reports are in error/unconfirmed (Wu, 1989; Cordeiro, 1999; Clarke et al., 2003).

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: occurs (regularly, as a native taxon) in multiple nations

U.S. & Canada State/Province Distribution
United States AL, AR, CO, CT, DC, DE, GA, IA, IL, IN, KS, KY, LA, MA, MD, ME, MI, MN, MO, MS, NC, ND, NE, NH, NJ, NY, OH, OK, PA, RI, SC, SD, TN, TX, VA, VT, WI, WV
Canada MB, NB, NS, ON, QC, SK

Range Map
No map available.

U.S. Distribution by County Help
State County Name (FIPS Code)
DE Kent (10001)
IA Allamakee (19005), Black Hawk (19013), Bremer (19017), Buchanan (19019), Carroll (19027), Cerro Gordo (19033), Chickasaw (19037), Clayton (19043), Clinton (19045), Delaware (19055), Des Moines (19057), Dubuque (19061), Floyd (19067), Franklin (19069), Greene (19073), Hamilton (19079), Hardin (19083), Howard (19089), Humboldt (19091), Jackson (19097), Johnson (19103), Jones (19105), Linn (19113), Louisa (19115), Mitchell (19131), Muscatine (19139), Sac (19161), Scott (19163), Story (19169), Washington (19183), Webster (19187), Winneshiek (19191)
KS Allen (20001), Anderson (20003), Bourbon (20011), Chase (20017), Chautauqua (20019), Cherokee (20021), Coffey (20031), Cowley (20035), Dickinson (20041), Elk (20049), Franklin (20059), Greenwood (20073), Jackson (20085), Labette (20099), Lyon (20111), Marion (20115), Marshall (20117), Miami (20121), Montgomery (20125), Morris (20127), Neosho (20133), Shawnee (20177), Wabaunsee (20197), Wilson (20205)
LA Claiborne (22027), Lincoln (22061)*, Madison (22065), Rapides (22079), Union (22111)*
MA Berkshire (25003), Bristol (25005)*, Franklin (25011), Hampden (25013), Hampshire (25015), Middlesex (25017), Norfolk (25021), Plymouth (25023), Worcester (25027)
MD Allegany (24001), Caroline (24011), Carroll (24013), Cecil (24015), Frederick (24021), Garrett (24023), Harford (24025), Howard (24027), Kent (24029), Montgomery (24031), Prince Georges (24033), Queen Annes (24035), Talbot (24041), Washington (24043)
MS Coahoma (28027), Copiah (28029), Issaquena (28055), Marshall (28093), Montgomery (28097), Tishomingo (28141)
NC Alamance (37001), Alexander (37003), Anson (37007), Buncombe (37021), Burke (37023), Cabarrus (37025), Caldwell (37027), Caswell (37033), Catawba (37035), Chatham (37037), Davidson (37057)*, Durham (37063), Edgecombe (37065), Forsyth (37067), Franklin (37069), Gaston (37071), Granville (37077), Halifax (37083), Harnett (37085)*, Henderson (37089), Johnston (37101), Jones (37103), Lee (37105), Mecklenburg (37119), Montgomery (37123), Moore (37125), Nash (37127), Orange (37135), Person (37145), Pitt (37147), Polk (37149)*, Randolph (37151), Richmond (37153), Rockingham (37157), Stanly (37167), Surry (37171), Transylvania (37175), Union (37179), Vance (37181), Wake (37183), Warren (37185), Wilkes (37193), Wilson (37195), Yadkin (37197)
NJ Bergen (34003), Gloucester (34015), Hunterdon (34019), Mercer (34021), Morris (34027), Passaic (34031), Salem (34033), Somerset (34035), Sussex (34037), Warren (34041)
OK Le Flore (40079), McCurtain (40089), Nowata (40105), Pushmataha (40127)
SC Chesterfield (45025), Edgefield (45037), Lancaster (45057), McCormick (45065), Richland (45079), Saluda (45081)
SD Brookings (46011), Davison (46035), Deuel (46039), Grant (46051), Hamlin (46057), Hutchinson (46067), Lincoln (46083), McCook (46087)*, Minnehaha (46099), Moody (46101), Roberts (46109), Turner (46125)*, Union (46127), Yankton (46135)
TN Hancock (47067)
TX Anderson (48001), Angelina (48005), Bexar (48029), Cass (48067), Cherokee (48073), Harrison (48203), Marion (48315), Nacogdoches (48347), Panola (48365), San Augustine (48405)
VA Scott (51169)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
01 Nashua (01070004)+, Concord (01070005)+, Middle Connecticut (01080201)+, Miller (01080202)+, Deerfield (01080203)+*, Chicopee (01080204)+, Westfield (01080206)+, Farmington (01080207)+, Charles (01090001)+, Cape Cod (01090002)+, Blackstone (01090003)+, Narragansett (01090004)+*, Quinebaug (01100001)+, Housatonic (01100005)+
02 Rondout (02020007)+, Hackensack-Passaic (02030103)+, Raritan (02030105)+, Middle Delaware-Mongaup-Brodhead (02040104)+, Middle Delaware-Musconetcong (02040105)+, Lower Delaware (02040202)+, Cohansey-Maurice (02040206)+, Lower Susquehanna (02050306)+, Chester-Sassafras (02060002)+, Choptank (02060005)+, Patuxent (02060006)+, North Branch Potomac (02070002)+, Cacapon-Town (02070003)+, Conococheague-Opequon (02070004)+, Middle Potomac-Catoctin (02070008)+, Monocacy (02070009)+, Middle Potomac-Anacostia-Occoquan (02070010)+
03 Middle Roanoke (03010102)+, Lower Dan (03010104)+, Upper Tar (03020101)+, Fishing (03020102)+, Lower Tar (03020103)+, Upper Neuse (03020201)+, Contentnea (03020203)+, Lower Neuse (03020204)+, Haw (03030002)+, Deep (03030003)+, Upper Cape Fear (03030004)+*, Upper Yadkin (03040101)+, Lower Yadkin (03040103)+, Upper Pee Dee (03040104)+, Rocky, North Carolina, (03040105)+, Lower Pee Dee (03040201)+, Lynches (03040202)+, Upper Catawba (03050101)+, Upper Broad (03050105)+*, Lower Broad (03050106)+, Saluda (03050109)+, Stevens (03060107)+
05 Youghiogheny (05020006)+
06 Upper French Broad (06010105)+, Upper Clinch (06010205)+, Bear (06030006)+
07 Upper Minnesota (07020001)+, Lac Qui Parle (07020003)+, Coon-Yellow (07060001)+, Upper Iowa (07060002)+, Grant-Little Maquoketa (07060003)+, Turkey (07060004)+, Apple-Plum (07060005)+, Maquoketa (07060006)+, Lower Wisconsin (07070005)+, Copperas-Duck (07080101)+, Upper Wapsipinicon (07080102)+, Flint-Henderson (07080104)+, South Skunk (07080105)+, Skunk (07080107)+, Upper Cedar (07080201)+, Shell Rock (07080202)+, Winnebago (07080203)+, West Fork Cedar (07080204)+, Middle Cedar (07080205)+, Lower Cedar (07080206)+, Upper Iowa (07080207)+, Lower Iowa (07080209)+, Middle Des Moines (07100004)+, Boone (07100005)+, North Raccoon (07100006)+
08 Lower Mississippi-Greenville (08030100)+, Coldwater (08030204)+, Big Sunflower (08030207)+, Bayou D'arbonne (08040206)+, Tensas (08050003)+, Upper Big Black (08060201)+, Bayou Pierre (08060203)+, Bayou Teche (08080102)+
09 Bois De Sioux (09020101)+
10 Lower James (10160011)+, Vermillion (10170102)+*, Upper Big Sioux (10170202)+, Lower Big Sioux (10170203)+, Boyer (10230007)+, Lower Smoky Hill (10260008)+, Upper Kansas (10270101)+, Middle Kansas (10270102)+, Delaware (10270103)+, Lower Big Blue (10270205)+, Upper Marais Des Cygnes (10290101)+, Little Osage (10290103)+, Marmaton (10290104)+
11 Kaw Lake (11060001)+, Upper Verdigris (11070101)+, Fall (11070102)+, Middle Verdigris (11070103)+, Elk (11070104)+, Caney (11070106)+, Neosho headwaters (11070201)+, Upper Cottonwood (11070202)+, Lower Cottonwood (11070203)+, Upper Neosho (11070204)+, Middle Neosho (11070205)+, Spring (11070207)+, Kiamichi (11140105)+, Upper Little (11140107)+, Caddo Lake (11140306)+
12 Middle Sabine (12010002)+, Upper Neches (12020001)+, Upper Angelina (12020004)+, Lower Angelina (12020005)+, Upper San Antonio (12100301)+
+ 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
Reproduction Comments: The creeper is a long-term brooder, with eggs fertilized in the summer and glochidia released the following spring. Van Snik Gray et al. (2002) found glochidia released 26 April to 2 June in laboratory conditions mimicking Pennsylvania stream habitats. Laboratory studies by Ellis and Keim (1918) revealed plains killifish (Fundulus zebrinus) and green sunfish (Lepomis cyanellis) as glochidial hosts as well as creek chub (Semotilus atromaculatus) according to Baker (1928). Later studies by Hillegass and Hove (1997) found the following fish to be suitable hosts: black bullhead (Ameiurus melas), largemouth bass (Micropterus salmoides), green sunfish (Lepomis cyanellus), black bullhead (Ameirus natalis), and yellow perch (Perca flavescens). Previous studies by Hove (1995) and Hove et al. (1997) also revealed fathead minnow (Pimephales promelas), spotfin shiner (Cyprinella spiloptera), walleye (Stizostedion vitreum), and bluegill (Lepomis macrochirus) as glochidial hosts. Wicklow and Beisheim (1998) found the following fish to be suitable hosts: the longnose dace (Rhinichthys cataractae), fallfish (Semotilus corporalis), golden shiner (Notemigonus crysoleucas), and slimy sculpin (Cottus cognatus). They also found that the larvae of the northern two-lined salamander (Eurycea bislineata) was a suitable glochidial host. Watters et al. (1998a; 1998b; 1999) documented other hosts including fantail darter (Etheostoma flabellare), banded darter (Etheostoma zonale), sand shiner (Notropis lundibundus), bluntnose minnow (Pimephales notatus), and white crappie (Pomoxis annularis). Van Snik Gray et al. (1999; 2002) found 15 hosts (10 of which were previously unknown) bringing the total number to 29, second only to Pyganodon grandis at 32. New host species reported by Van Snik Gray et al. (1999; 2002) include: Acipenser oxyrhynchus- Atlantic sturgeon, Campostoma anomalum- central stoneroller, Luxilus cornutus- common shiner, Nocomis micropogon- river chub, Rhinichthys atratulus- blacknose dace, Oncorhynchus mykiss- rainbow trout, Salvelinus fontinalis- brook charr, Ambloplites rupestris- rock bass, Etheostoma olmstedi- tessellated darter, and Notophthalmus viridescens- red-spotted newt. Recent studies (include those mentioned above) are contrary to early reports (Lefevre and Curtis, 1911) that this species may metamorphose without a host. This species utilizes amphibians as well as fish for hosts. Cliff et al. (2001) futher documented central stoneroller (Campestoma anomalum), brook stickleback (Culaea inconstans), rainbow darter (Etheostoma caeruleum), Iowa darter (Etheostoma exile), Johnny darter (Etheostoma nigrum), channel catfish (Ictalurus punctatus), pumpkinseed (Lepomis gibbosus), burbot (Lota lota), smallmouth bass (Micropteris dolomieu), spottail shiner (Notropis hudsonius), logperch (Percina caprodes), blackside darter (Percina maculata), slenderhead darter (Percina phoxocephala), northern redbelly dace (Phoxinus eos), black crappie (Pomoxis nigromaculatus), blacknose dace (Rhinichthys atratulus), creek chub (Semotilus atromaculatus), and central mudminnow (Umbra limi). New host fish confirmation from Watters et al. (2005): rainbow darter (Etheostoma caeruleum), red-eared sunfish (Lepomis microlophus). Watters et al. (2006) include Ameirus nebulosus brown bullhead, Etheostoma zonale banded darter, and Percina caprodes logperch as hosts. Hove (1995) and Hove et al. (1997) list Cyprinella spiloptera spotfin shiner
Habitat Type: Freshwater
Non-Migrant: N
Locally Migrant: N
Long Distance Migrant: N
Riverine Habitat(s): BIG RIVER, CREEK, Low gradient, MEDIUM RIVER, Moderate gradient, Pool, Riffle
Lacustrine Habitat(s): Shallow water
Special Habitat Factors: Benthic
Habitat Comments: This species is a habitat generalist, with a wide distribution. It is usually found in streams and rivers in a range of flow conditions (rarely in high-gradient streams of mountainous regions) but can tolerate lakes and ponds, particularly in outlets.
Economic Attributes Not yet assessed
Management Summary Not yet assessed
Population/Occurrence Delineation
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 ( for a complete list of freshwater mussel taxa sorted by flow regime.
Population/Occurrence Viability
U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
NatureServe Conservation Status Factors Edition Date: 31Dec2011
NatureServe Conservation Status Factors Author: Cordeiro, J.
Element Ecology & Life History Edition Date: 31Dec2011
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).

  • Baker, F.C. 1928b. The freshwater Mollusca of Wisconsin: Part II. Pelecypoda. Bulletin of the Wisconsin Geological and Natural History Survey, University of Wisconsin, 70(2): 1-495.

  • Becker, A.J., R. Gauza, and J.A. Smith. 2006. A summary of Freshwater Mussel data collected by the Maryland Biological Stream Survey 1995-2006. MD DNR-MBSS, Annapolis. 28 pp.

  • 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 T. Proch. 1995. Manual of the freshwater bivalves of Maryland. Prepared for a workshop held at Versar, Inc., Columbia, Maryland, 9 March 1995. 68 pp.

  • Branson, B.A. 1966a. A partial biological survey of the Spring River drainage in Kansas, Oklahoma and Missouri. Part I, collecting sites, basic limnological data, and mollusks. Transactions of the Kansas Academy of Science 69(3/4): 242-293.

  • Burch, J.B. 1975. Freshwater unionacean clams (mollusca: pelecypoda) of North America. Malcological Publications. Hamburg, Michigan. 204 pp.




  • Christian, A.D. 1995. Analysis of the commercial mussel beds in the Cache and White Rivers in Arkansas. M.S. Thesis, Arkansas State University. 210 pp.

  • Clark, C.F. 1988. Some fresh-water mussels from the Red River drainage, Kentucky. Malacology Data Net, 2(3/4): 100-104.

  • Clarke, A.H. 1981a. The freshwater mollusks of Canada. National Museum of Natural Sciences, National Museums of Canada, D. W. Friesen and Sons, Ltd.: Ottawa, Canada. 446 pp.

  • Clarke, A.H. and C.O. Berg. 1959. The freshwater mussels of central New York. Cornell University Agricultural Experiment Station Memoir 367.

  • Clarke, A.H., P. Hovingh, and J.J. Clarke. 2003. A survey of the freshwater mollusks and crayfishes of eastern Colorado, at altitudes of less than 6000 feet, carried out during 2001 and 2002. Final Report to Colorado Division of Wildlife, State of Colorado, contract PSC-701-2001, 25 June 2003. 61 pp. + tabs. + app.

  • Clayton, J.L., C.W. Stihler, and J.L. Wallace. 2001. Status of and potential impacts to the freshwater bivalves (Unionidae) in Patterson Creek, West Virginia. Northeastern Naturalist 8(2):179-188.

  • Cliff, M., M. Hove, and M. Haas. 2001. Creeper glochidia appear to be host generalists. Ellipsaria, 3(1): 19-20.

  • Cordeiro, J. 1999. Distribution and habitat of freshwater mussels (Bivalvia: Unionoida: Unionidae) in Colorado. Natural History Inventory of Colorado, 19: 1-56.

  • Cummings, K.S. and J.M. Berlocher. 1990. The naiades or freshwater mussels (Bivalvia: Unionidae) of the Tippecanoe River, Indiana. Malacological Review 23:83-98.

  • Cvancara, A.M. 1970. Mussels (Unionidae) of the Red River Valley in North Dakota and Minnesota, U.S.A.. Malacologia, 10(1): 57-92.

  • Davis, D.S. 1999. Reports of museum visits and field collections related to studies of the distribution of the freshwater mussels Lampsilis cariosa (Say, 1817) and Leptodea ochracea (Say, 1817), Mollusca, Unionidae in New Brunswick and Nova Scotia in 1999. Unpublished, 23 pp.

  • Davis, M. 1987. Freshwater mussels (Mollusca: Bivalvia: Unionidae) of the Cannon River drainage in southeastern Minnesota. Final report submitted to the Nongame Wildlife Program, Minnesota Department of Natural Resources. 21 pp. + figures and original data sheets.

  • Davis, Mike. 1987. Freshwater Mussels (Mollusca: Bivalvia: Unionidae) of the Cannon River Drainage in Southeastern Minnesota. Funded by the MN DNR, Section of Wildlife, Nongame Research Program. Results in unpublished report.

  • Ecological Specialists, Inc. 1996. Unionid Mussel Survey of the Blue River, Indiana. Prepared for The Nature Conservancy. 23 pp.

  • Ellis, M.M. and M. Keim. 1918. Notes on the glochidia of Strophitus edentulus pavonius (Lea) from Colorado. The Nautilus, 32(1): 17-18.


  • Freeman, P.W. and K. Perkins. 1992. Survey of mollusks of the Platte River: Final Report. Report to the U.S. Fish and Wildlife Service, Grand Island, Nebraska, March 1992. 28 pp. + app.

  • Freeman, P.W. and K. Perkins. 1997. Survey of mollusks of the Niobrara River. Final Report to the U.S. Fish and Wildlife Service, Grand Island, Nebraska, September 1997. 22 pp.

  • General Status 2015, Environment Canada. 2015. Manitoba Mollusk species list and subnational ranks proposed by an expert.

  • Harmon, J.L. 1992. Naiades (Bivalvia: Unionidae) of Sugar Creek, east fork White River drainage, in central Indiana. Malacology Data Net 3(1-4):31-42.

  • Hillegass, K.R. and M.C. Hove. 1997. Suitable fish hosts for glochidia of three freshwater mussels: strange floater, ellipse, and snuffbox. Triannual Unionid Report, 13: 25.

  • Hoke, E. 2004. The freshwater mussels (Mollusca: Bivalvia: Unionidae) of the Little Blue River drainage of northeastern Kansas and southeastern Nebraska. Transactions of the Nebraska Academy of Sciences, 29: 7-24.

  • Hoke, E. 2005b. The unionid mussels (Mollusca: Bivalvia: Unionidae) of the Big Blue River basin of northeastern Kansas and southeastern Nebraska. Transactions of the Nebraska Academy of Sciences, 30: 33-57.

  • Hove, M.C. 1995. Early life history research on the squawfoot, Strophitus undulatus. Triannual Unionid Report, 7: 28-29.

  • Hove, M.C., R.A. Engelking, M.E. Peteler, E.M. Peterson, A.R. Kapuscinski, L.A. Sovell, and E.R. Evers. 1997. Suitable fish hosts for glochidia of four freshwater mussels. Pages 21-25 in: K.S. Cummings, A.C. Buchanan, C.A. Mayer, and T.J. Naimo (eds.). Conservation and Management of Freshwater Mussels II. Proceedings of a UMRCC Symposium, 16-18 October 1995, St. Louis, Missouri. 293 pp.

  • Howard, A.D. 1914. A second case of metamorphosis without parasitism in the Unionidae. Science, 40: 353-355.

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

  • Jones, J.W. and R.J. Neves. 2007. Freshwater mussel status: Upper North Fork Holston River, Virginia. Northeastern Naturalist, 14(3): 471-480.

  • Jones, J.W., R.J. Neves, M.A. Patterson, C.R. Good, and A. DiVittorio. 2001. A status survey of freshwater mussel populations in the upper Clinch River, Tazewell County, Virginia. Banisteria, 17: 20-30.

  • Kesler, D. H., D. Manning, N. Van Tol, L. Smith, and B. Sepanski. 2001. Freshwater mussels (Unionidae) of the Wolf River in western Tennessee and Mississippi. Journal of the Tennessee Academy of Science 76(1):38-46.

  • 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. 1911. Metamorphosis without parasitism in the Unionidae. Science, 33(857): 863-865.

  • 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.

  • Lyons, M.S., R.A. Krebs, J.P. Holt, L.J. Rundo, and W. Zawiski. 2007. Assessing causes of change in the freshwater mussels (Bivalvia: Unionidae) in the Black River, Ohio. American Midland Naturalist, 158: 1-15.


  • Mather, C.M., and J.A M. Bergmann. 1994. Freshwater mussels of the Cypress Bayou system, northeast Texas. Malacology Data Net, 3(5/6): 139-145.

  • Mohler, J.W., P. Morrison, and J. Haas. 2006. The mussels of Muddy Creek on Erie National Wildlife Refuge. Northeastern Naturalist 13(4):569-582.

  • 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.

  • Nedeau, E.J., M.A. McCollough, and B.I. Swartz. 2000. The Freshwater Mussels of Maine. Maine Department of Inland Fisheries and Wildlife, Augusta, Maine. 118 pp.

  • Nickens, T. 1994. Printout of all computerized District of Columbia mollusk specimens at the U.S. National Museum. Printout of 22 December. 4 pp.


  • Ortmann, A.E. 1919. Monograph of the naiades of Pennsylvania. Part III. Systematic account of the genera and species. Memoirs of the Carnegie Museum 8(1):1-385.

  • Ortmann, A.E. and B. Walker. 1922. On the nomenclature of certain North American naiades. Occasional Papers of the Museum of Zoology, University of Michigan, 112: 1-75.



  • Parmalee, P.W. and A.E. Bogan. 1998. The freshwater mussels of Tennessee. University of Tennessee Press, Knoxville, Tennesee. 328 pp.

  • Perkins III, K. and D.C. Backlund. 2003. A survey for winged mapleleaf (Quadrula fragosa) and scaleshell (Leptodea leptodon) in the James River, South Dakota. South Dakota Game, Fish and Parks, Pierre, South Dakota, Report GFP 2003-17. 21 pp.

  • Pip, E. 2000. The decline of freshwater molluscs in southern Manitoba. Canadian Field Naturalist 114(4):555-560.

  • Pip, E. 2006. Littoral mollusc communities and water quality in southern Lake Winnipeg, Manitoba, Canada. Biodiversity and Conservation, 15: 3637-3652.

  • Posey, W.R., III, J.L. Harris, and G.L. Harp. 1996b. An evaluation of the mussel community in the Lower Ouachita River. Report to the Arkansas Game and Fish Commission, Arkansas. 28 pp.





  • Schanzle, R.W. and K.S. Cummings. 1991. A survey of the freshwater mussels (Bivalvia: Unionidae) of the Sangamon River basin, Illinois. Illinois Natural History Survey Biological Notes, 137: 1-25.

  • Schanzle, R.W., G.W. Kruse, J.A. Kath, R.A. Klocek, and K.S. Cummings. 2004. The freshwater mussels (Bivalvia: Unionidae) of the Fox River basin, Illinois and Wisconsin. Illinois Natural History Biological Notes, 141: 1-35.

  • Sethi, S.A., A.R. Selle, M.W. Doyle, E.H. Stanley, and H.E. Kitchel. 2004. Response of unionid mussels to dam removal in Koshkonong Creek, Wisconsin (USA). Hydrobiologia, 525: 157-165.

  • Skadsen, D.R. and K. Perkins III. 2000. Unionid mussels of the Big Sioux River and tributaries: Moody, Minnehaha, Lincoln, and Union Counties, South Dakota. GFP Report 2000-9 to the South Dakota Department of Game, Fish, and Parks, Pierre, South Dakota. 52 pp.

  • Smith, D.G. 2000a. Keys to the Freshwater Macroinvertebrates of Southern New England. Douglas G. Smith: Sunderland, Massachusetts. 243 pp.

  • Smith, T.A. and D. Crabtree. 2010. Freshwater mussel (Unionidae: Bivalvia) distributions and densities in French Creek, Pennsylvania. Northeastern Naturalist 17(3):387-414.

  • Spoo, A. 2008. The Pearly Mussels of Pennsylvania. Coachwhip Publications: Landisville, Pennsylvania. 210 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. 1991. The freshwater mussels (Bivalvia: Unionoidea) of the upper Delaware River drainage. American Malacological Bulletin 9(1):21-25.

  • 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.

  • Strayer, David L. 1987. Ecology and zoogeography of the freshwater mollusks of the Hudson River basin. Malacological Review 20:1-68.

  • Strayer, David L. and K.J. Jirka. 1997. The Pearly Mussels (Bivalva: Unionoidea) of New York State. New York State Museum Memoir 26. The New York State Education Department.

  • Strecker, J.K. 1931. The naiades or pearly fresh-water mussels of Texas. Baylor University Museum Special Bulletin, 2: 1-71.

  • The Catena Group. 2006. Freshwater mussel surveys of the Pee Dee River basin in South Carolina. Unpublished report prepared for the Nature Conservancy- South Carolina Chapter, January 3, 2006. 47 pp.

  • Turgeon, D.D., A.E. Bogan, E.V. Coan, W.K. Emerson, W.G. Lyons, W.L. Pratt, C.F.E. Roper, A. Scheltema, E.G. Thompson, and J.D. Williams. 1988. Common and scientific names of aquatic invertebrates from the US and Canada: mollusks. Am. Fish. Soc. Spec. Publ. 16:1-277.

  • 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 Snik Gray, E.S., W.A. Lellis, J.C. Cole, and C.S. Johnson. 1999. Hosts of Pyganodon cataracta (eastern floater) and Strophitus undulatus (squawfoot) from the Upper Susquehanna River basin, Pennsylvania. Triannual Unionid Report, 18: 6.

  • Van Snik Gray, E.V.S., W.A. Lellis, J.C. Cole, and C.S. Johnson. 2002. Host identification for Strophitus undulatus (Bivalvia: Unionidae), the creeper, in the upper Susquehanna River basin, Pennsylvania. American Midland Naturalist, 147: 153-161.

  • 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.

  • Vaughn, C.C. 2000. Changes in the mussel fauna of the middle Red River drainage: 1910 - present. Pages 225-232 in R.A. Tankersley, D.I. Warmolts, G.T. Watters, B.J. Armitage, P.D. Johnson, and R.S. Butler (eds.). Freshwater Mollusk Symposia Proceedings. Ohio Biological Survey, Columbus, Ohio. 274 pp.

  • Vaughn, C.C. and D.E. Spooner. 2004. Status of the mussel fauna of the Poteau River and implications for commercial harvest. American Midland Naturalist, 152: 336-346.

  • Vaughn, C.C., and C.M. Taylor. 1999. Impoundments and the decline of freshwater mussels: a case study of an extinction gradient. Conservation Biology 13(4):912-920.

  • Vila, P., R. Villella, and L. Bailey. 2003. Distribution and diversity of native freshwater mussels in the Sleepy and Opequon Creek watersheds in the eastern panhandle, West Virginia. Abstract of the North American Benthological Society Annual Meeting, Athens, Georgia.

  • Watson, E.T., L.C. Graham, and W.G. Franzin. 1998. The distribution of Unionidae (Mollusca: Bivalvia) in the Assiniboine River drainage in Manitoba. Canadian Technical Report of Fisheries and Aquatic Sciences 2232. Central and Arctic Region, Department of Fisheries and Oceans, Winnipeg, MB. 32 p.

  • Watters, G. Thomas. 1994. An Annotated Bibliography of the Reproduction and Propogation of the Unionoidea (Primarily of North America). Ohio Biological Survey, College of Biological Sciences, The Ohio State University. In cooperation with Ohio Division of Wildlife. 158 pp.

  • Watters, G. Thomas. 1996. 1996 Survey of the Mussels of the Fish Creek Drainage. Final Report to the Indiana Chapter of The Nature Conservancy.

  • Watters, G.T, S.H. O'Dee, and S. Chordas. 1998b. A 'kinetic' conglutinate in Strophitus undulatus (Say, 1817). Triannual Unionid Report, 16: 27.

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

  • Watters, G.T. 1992b. Distribution of the Unionidae in south central Ohio. Malacology Data Net 3(1-4):56-90.

  • Watters, G.T. 2002. The kinetic conglutinate of the creeper freshwater mussel, Strophitus undulatus (Say, 1817). Journal of Molluscan Studies, 68: 155-158.

  • Watters, G.T., S.H. O'Dee, and S. Chordas. 1998a. New potential hosts for: Strophitus undulatus- Ohio River drainage; Strophitus undulatus- Susquehanna River drainage; Alasmidonta undulata- Susquehanna River drainage; Actinonaias ligamentina- Ohio River drainage; and Lasmigona costata- Ohio River drainage. Triannual Unionid Report 15: 27-29.

  • Watters, G.T., S.W. Chordas, S.H. O'Dee, and J. Reiger. 1999. Host identification studies for six species of Unionidae. Pages 75-76 in Program Guide & Abstract of the First Symposium of the Freshwater Conservation Society, 17-19 March 1999, Chattanooga, Tennessee. 92 pp.

  • Watters, G.T., T. Menker, B. Smith, K. Harraman, and K. Kuehnl. 2006. Host identifications or confirmations. Ellipsaria, 8(2): 8.

  • Watters, G.T., T. Menker, S. Thomas, and K. Luehnl. 2005. Host identifications or confirmations. Ellipsaria, 7(2): 11-12.

  • Wendeln, K.L., J.R. Runkle, and G.T. Watters. 2009. The freshwater mussels (Unionidae) of Twin Creek, Southwest Ohio. Journal of Freshwater Ecology 24(3):451-460. DOI: 10.1080/02705060.2009.9664318

  • Wicklow, B.J. and P.M. Beisheim. 1998. Life history studies of the squawfoot mussel Strophitus undulatus in the Piscataquog River watershed, New Hampshire. Page 41 in Conservation, Captive Care, and Propagation. Freshwater Mussels Symposium Program and Abstracts, 6-8 March 1998, Columbus, Ohio. 43 pp.

  • 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.

  • Wu, S.-K. 1989. Colorado freshwater mollusks. Natural History Inventory of Colorado 11: 1-117.

References for Watershed Distribution Map
  • Ahlstedt, S.A. and J.J. Jenkinson. 1991. Distribution and abundance of Potamilus capax and other freshwater mussels in the St. Francis River system, Arkansas and Missouri, U.S.A. Walkerana, 5(14): 225-261.

  • 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.

  • Ashton, M. 2009. Recent mussel surveys in the Susquehanna River, below Conowingo Dam, Maryland. Ellipsaria 11(3):12.

  • Athearn, H.D. 1961. Additions to the New Brunswick checklist. Sterkiana 4:33-34.

  • Athearn, H.D. and A.H. Clarke, Jr. 1962. The freshwater mussels of Nova Scotia. National Museum of Canada Bulletin 183:11-41.

  • Backlund, D.C. 2000. Summary of current known distribution and status of freshwater mussels (Unionoida) in South Dakota. Central Plains Archaeology, 8(1): 69-77.

  • Badra, P.J. and R.R. Goforth. 2003. Freshwater mussel surveys of Great Lakes tributary rivers in Michigan. Report Number MNFI 2003-15 to the Michigan Department of Environmental Quality, Coastal Zone Management Unit, Lansing, Michigan. 40 pp.

  • Bogan, A.E. 1993a. Workshop on freshwater bivalves of Pennsylvania. Workshop hosted by Aquatic Systems Corporation, Pittsburgh, Pennsylvania, held at Carnegie Museum of Natural History, Pittsburgh, Pennsylvania, 6-7 May 1993. 80 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.

  • Branson, B.A. 1983. The mussels (Unionacea: Bivalvia) of Oklahoma - Part II: the Unioninae, Pleurobemini, and Anodontini. Proceedings of the Oklahoma Academy of Science, 63: 49-59

  • Chapman, E.J. and T.A. Smith. 2008. Structural community changes in freshwater mussel populations of Little Mahoning Creek, Pennsylvania. American Malacological Bulletin, 26: 161-169.

  • Cicerello, R.R. and G.A. Schuster. 2003. A guide to the freshwater mussels of Kentucky. Kentucky State Nature Preserves Commission Scientific and Technical Series 7:1-62.

  • Clarke, A.H. 1992. Ontario's Sydenham River, an important refugium for native freshwater mussels against competition from the zebra mussel, Dreissena polymorpha. Malacology Data Net, 3(1-4): 43-55.

  • Clarke, A.H. and A.M. Rick. 1963 [1964]. Supplementary records of Unionacea from Nova Scotia with a discussion of the identity of Anodonta fragilis Lamarck. National Museum of Canada Bulletin, Biological Science Series, 199(72): 15-27.

  • Clench, W.J. and K.J. Boss. 1967. Fresh water Mollusca from James River, VA, and a new name for Mudalia of authors. The Nautilus, 80(3): 99-102.

  • Cordeiro, J. 2003c. Freshwater Mussels of the New York Metropolitan Region and New Jersey. A Guide to Their Identification, Biology and Conservation. American Museum of Natural History, New York. Available online:

  • Couch, K.J. 1997. An Illustrated Guide to the Unionid Mussels of Kansas. Karen J. Couch. [Printed in Olathe, Kansas]. 124 pp.

  • Cummings, K.S. and C.A. Mayer. 1997. Distributional checklist and status of Illinois freshwater mussels (Mollusca: Unionacea). Pages 129-145 in: K.S. Cummings, A.C. Buchanan, C.A. Mayer, and T.J. Naimo (eds.) Conservation and management of freshwater mussels II: initiatives for the future. Proceedings of a UMRCC Symposium, October 1995, St. Louis, Missouri. Upper Mississippi River Conservation Committee, Rock Island, Illinois.

  • Cvancara, A.M. 1983. Aquatic mollusks of North Dakota. Report of Investigation No. 78, North Dakota Geological Survey. Kay's, Inc., Jamestown, North Dakota. 141 pp.

  • Fichtel, C. and D.G. Smith. 1995. The freshwater mussels of Vermont. Nongame and Natural Heritage Program, Vermont Fish and Wildlife Department. Technical Report 18. 54 pp.

  • Gabriel, M. 1995. Freshwater mussel distribution in the rivers and streams of Cheshire, Hillsborough, Merrimack & Rockingham Counties, New Hampshire. Unpublished report to New Hampshire Fish and Game Department, Concord, New Hampshire. 61 pp.

  • Galbraith, H.S., D.E. Spooner, and C.C. Vaughn. 2008. Status of rare and endangered freshwater mussels in southeastern Oklahoma. The Southwestern Naturalist, 53(1): 45-50.

  • Goodrich, C. and H. van der Schalie. 1939. Aquatic mollusks of the upper peninsula of Michigan. Miscellaneous Publications of the Museum of Zoology, University of Michigan, 43: 1-45.

  • Gordon, M.E. 1982. Mollusca of the White River, Arkansas and Missouri. The Southwestern Naturalist, 27(3): 347-352.

  • Gordon, M.E. 1985. Mollusca of Frog Bayou, Arkansas. The Nautilus, 99(1): 6-9.

  • Grabarkiewicz, J.D. 2008. Three years of unionid surveys in Swan Creek, Lower Maumee River watershed, Lucas Co., OH. Final Report to the Ohio Division of Wildlife, Toledo Naturalists' Association, and Metroparks of the Toledo Area, Toledo, Ohio. 18 pp. + app.

  • Graf, D.L. 1997. Distribution of unionoid (Bivalvia) faunas in Minnesota, USA. The Nautilus, 110(2): 45-54.

  • Harmon, J.L. 1989. Freshwater bivalve mollusks (Bivalvia: Unionidae) of Graham Creek, a small southeastern Indiana stream. Malacology Data Net, 2(5/6): 113-121.

  • Hoggarth, M.A., D.A. Kimberly, and B.G. Van Allen. 2007. A study of the mussels (Mollusca: Bivalvia: Unionidae) of Symmes Creek and tributaries in Jackson, Gallia and Lawrence Counties, Ohio. Ohio Journal of Science 107(4):57-62.

  • Howells, R.G., R.W. Neck, and H.D. Murray. 1996. Freshwater Mussels of Texas. Texas Parks and Wildlife Press: Austin, Texas. 218 pp.

  • Jones, R.L., W.T. Slack, and P.D. Hartfield. 2005. The freshwater mussels (Mollusca: Bivalvia: Unionidae) of Mississippi. Southeastern Naturalist, 4(1): 77-92.

  • Mathiak, H.A. 1979. A river survey of the unionid mussels of Wisconsin, 1973-1977. Sand Shell Press: Horicon, Wisconsin. 75 pp.

  • Metcalfe-Smith, J.L. and B. Cudmore-Vokey. 2004. National general status assessment of freshwater mussels (Unionacea). National Water Research Institute / NWRI Contribution No. 04-027. Environment Canada, March 2004. Paginated separately.

  • Mirarchi, R.E., J.T. Garner, M.F. Mettee, and P.E. O'Neil. 2004b. Alabama wildlife. Volume 2. Imperiled aquatic mollusks and fishes. University of Alabama Press, Tuscaloosa, Alabama. xii + 255 pp.

  • Morris, T.J. and J. Di Maio. 1999. Current distributions of freshwater mussels (Bivalvia: Unionidae) in rivers of southwestern Ontario. Malacological Review, 31/32(1): 9-17.

  • Mulcrone, R.S. and C. Mehne. 2001. Freshwater mussels of the Kalamazoo River, Michigan, from Battle Creek to Saugatuck. Report prepared for U.S. Fish and Wildlife Service, East Lansing, Michigan. 15 pp.

  • Nedeau, E.J. and J. Victoria. 2003. A Field Guide to the Freshwater Mussels of Connecticut. Connecticut Department of Environmental Protection, Hartford, Connecticut. 31 pp.

  • Oesch, R.D. 1995. Missouri Naiades. A Guide to the Mussels of Missouri. Second edition. Missouri Department of Conservation: Jefferson City, Missouri. viii + 271 pp.

  • Parmalee, P.W. and A.E. Bogan. 1998. The Freshwater Mussels of Tennessee. University of Tennessee Press: Knoxville, Tennessee. 328 pp.

  • Posey II, W.R. 1997. Location, species composition and community estimates for mussel beds in the St. Francis and Ouachita Rivers, Arkansas. M.S. Thesis, Arkansas State University. 178 pp.

  • Raithel, C.J. and R.H. Hartenstein. 2006. The status of freshwater mussels in Rhode Island. Northeastern Naturalist 13(1):103-116.

  • Schmidt, J.E. and M.A. Zeto. 1986. Naiad distribution in the Mud River drainage, southwestern West Virginia. Malacology Data Net, 1(4): 69-78.

  • Sietman, B.E. 2003. Field Guide to the Freshwater Mussels of Minnesota. Minnesota Department of Natural Resources: St. Paul, Minnesota. 144 pp.

  • Sietman, B.E., S.D. Whitney, D.E. Kelner, K.D. Blodgett, and H.L. Dunn. 2001. Post-extirpation recovery of the freshwater mussel (Bivalvia: Unionidae) fauna in the Upper Illinois River. Journal of Freshwater Ecology, 16(2): 273-281.

  • Spooner, D.E. and C.C. Vaughn. 2007. Mussels of the Mountain Fork River, Arkansas and Oklahoma. Publications of the Oklahoma Biological Survey, 2nd series, 8: 14-18.

  • Strayer, D. 1980. The freshwater mussels (Bivalvia: Unionidae) of the Clinton River, Michigan, with comments on man's impact on the fauna, 1870-1978. The Nautilus 94(4):142-149.

  • Strayer, D.L. and K.J. Jirka. 1997. The Pearly Mussels of New York State. New York State Museum Memoir 26. The University of the State of New York. 113 pp. + figures.

  • Taylor, R.W. 1985. Comments on the distribution of freshwater mussels (Unionacea) of the Potomac River headwaters in West Virginia. The Nautilus 99(2-3):84-87.

  • Tiemann, J.S., R.E. Szafoni, and K. Roman. 2005. Freshwater mussel (Bivalvia: Unionidae) survey of Kyte River, Ogle County, Illinois. Transactions of the Illinois State Academy of Science 98(3-4):159-169.

  • Tiemann, J.S.. 2006. Freshwater mussel (Bivalvia: Unionidae) survey of the Wakurusa River basin, Kansas. Transaction of the Kansas Academy of Science, 109(3/4): 221-230.

  • Trdan, R.J. and W.R. Hoeh. 1993. Relocation of two state-listed freshwater mussel species (Epioblasma torulosa rangiana and Epioblasma triquetra) in Michigan. Pages 100-105 in K.S. Cummings, A.C. Buchanan, and L.M. Koch. (eds.). Conservation and Management of Freshwater Mussels. Proceedings of a UMRCC Symposium, 12-14 October 1992, St. Louis, Missouri. Upper Mississippi River Conservation Committee, Rock Island, Illinois. 189 pp.

  • Vidrine, M.F. 1993. The Historical Distributions of Freshwater Mussels in Louisiana. Gail Q. Vidrine Collectibles: Eunice, Louisiana. xii + 225 pp. + 20 plates.

  • Watson, E.T. 2000. Distribution and life history of the Unionidae (Bivalvia: Mollusca) in the Assiniboine River drainage in Manitoba, with special reference to Anodontoides ferussacianus. MS Thesis, University of Manitoba, Winnipeg, Manitoba. 159 pp.

  • Watters, G.T. 1995a. A field guide to the freshwater mussels of Ohio. revised 3rd edition. Ohio Department of Natural Resources, Division of Wildlife, Columbus, Ohio. 122 pp.

  • Watters, G.T., M.A. Hoggarth, and D.H. Stansbery. 2009b. The Freshwater Mussels of Ohio. Ohio State University Press: Columbus, Ohio. 421 pp.

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

  • Wolf, C. and B. Stark. 2008. Survey of freshwater mussels (Bivalvia: Unionoidea) in the Marais des Cygnes River, Fall River, and Grouse Creek. Transactions of the Kansas Academy of Science 111(1/2):1-20.

  • Zeto, M.A., W.A. Tolin, and J.E. Schmidt. 1987. The freshwater mussels (Unionidae) of the upper Ohio River, Greenup and Belleville Pools, West Virginia. The Nautilus, 101: 182-185.

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