Leptodea ochracea - (Say, 1817)
Tidewater Mucket
Other English Common Names: tidewater mucket
Taxonomic Status: Accepted
Related ITIS Name(s): Lampsilis ochracea Say (TSN 79993) ;Leptodea ochracea (Say, 1817) (TSN 80186)
French Common Names: leptodée ocre
Unique Identifier: ELEMENT_GLOBAL.2.114703
Element Code: IMBIV24030
Informal Taxonomy: Animals, Invertebrates - Mollusks - Freshwater Mussels
Kingdom Phylum Class Order Family Genus
Animalia Mollusca Bivalvia Unionoida Unionidae Leptodea
Genus Size: B - Very small genus (2-5 species)
Check this box to expand all report sections:
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: Leptodea ochracea
Taxonomic Comments: The generic placement of species Leptodea ochracea is in doubt (Bogan, 1995). Smith (2000) proposes movement of ochracea from Leptodea to Ligumia based on similarities in the papilla of Ligumia ochracea and Ligumia nasuta. However, Bogan (1995) and Bogan and Alderman (2004) also include comments by Davis and Fuller (1981) that the type species of Ligumia, Ligumia recta, and Ligumia nasuta are incorrectly grouped together; and question placement in Ligumia. Cordeiro (2003) has demonstrably shown that the species was actually described earlier than 1817 as Mytilopsis fluvitilis Gmelin, 1791, a species mistakenly synonimized by Isaac Lea in 1817 with Pyganodon cataracta, but Cordeiro has successfully suppressed this senior name in favor of the better known species name ochraceus (ICZN, 2005). In North Carolina, Stiven and Alderman (1992) noted conchological and genetic differences of specimens from different habitats as well as significant differences from Lampsilis cariosa and Lampsilis radiata.
Conservation Status

NatureServe Status

Global Status: G3G4
Global Status Last Reviewed: 23Dec2011
Global Status Last Changed: 12Jul2005
Rounded Global Status: G3 - Vulnerable
Reasons: This is a widespread, though uncommon species along the coastal areas of the Atlantic Slope with noted declines in almost its entire range with some state level extirpations. Dispersal is limited to coastal plains ponds and rivers with direct connectivity to the Atlantic Ocean.
Nation: United States
National Status: N3N4 (17Jul2006)
Nation: Canada
National Status: N3 (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 Connecticut (S2), Delaware (S1), District of Columbia (SNR), Georgia (SU), Maine (S2), Maryland (S1S2), Massachusetts (S2), New Jersey (S2), New York (S1), North Carolina (S2), Pennsylvania (S1), Rhode Island (SNR), South Carolina (S2), Virginia (S3)
Canada New Brunswick (S3), Nova Scotia (S1)

Other Statuses

Committee on the Status of Endangered Wildlife in Canada (COSEWIC): Candidate (Low) (10Jul2017)
IUCN Red List Category: NT - Near threatened
American Fisheries Society Status: Special Concern (01Jan1993)

NatureServe Global Conservation Status Factors

Range Extent: 200,000-2,500,000 square km (about 80,000-1,000,000 square miles)
Range Extent Comments: This species is found along the Atlantic coastal plain from Cape Breton, Nova Scotia, to the Savannah River, Georgia (Johnson, 1970).

Area of Occupancy: 2,501 to >12,500 4-km2 grid cells
Area of Occupancy Comments:  

Number of Occurrences: 21 - 300
Number of Occurrences Comments: In Maine, 1997 surveys found 27 populations (29 sites) in four coastal watersheds such as Merrymeeting Bay and the St., George, Penobscot, lower Kennebec, and lower Androscoggin River drainages (absent from Androscoggin, Aroostook,Cumberland, Franklin, Oxford, Washington, and York Cos.) (Nedeau et al., 2000). In Massachusetts, this species is known only from large ponds and their outlets in coastal regions and in the Connecticut River (Smith, 2000). In Connecticut, it is known from the lower Connecticut River (Nedeau and Victoria, 2003). In Maryland, it is known from the Upper Potomac, Washington Metro, Susquehanna, Elk, and Chester River drainages (Bogan and Proch, 1995); recently the lower Susquehanna (Ashton, 2009). In New Jersey, it is known from the middle, lower, and upper Delaware basin (Cordeiro, 2003). In New York, it is only known from the lower and middle Hudson drainages (Strayer and Jirka, 1997). Virginia occurrences are scattered in the York, Ghowan, and Potomac basins (VA NHP, pers. comm., 2006). Bogan and Alderman (2004) list South Carolina distribution as the Waccamaw and Savannah River basins only. Recently, it was found at 3 sites in the Pee Dee River drainage (Little Pee Dee River), South Carolina (Catena Group, 2006). In North Carolina, it is known from the Waccamaw (including Lake Waccamaw- Johnson, 1984), Pamlico, Roanoke, Lower Tar, and Chowan (Alderman and Alderman, 2009) River basins (Stiven and Alderman, 1992); and possibly extirpated from the Neuse River basin (Bogan, 2002); including Bertie, Chowan, Columbus, Edgecombe (extirpated), Halifax, Hertford, Martin, Northampton, Pitt, and Washington Cos. (LeGrand et al., 2006). The species does not occur in Rhode Island (Raithel and Hartenstein, 2006) although it may once have (Cordeiro, 2004). In Canada, this species is secure in New Brunswick (Athearn, 1961) (new populations discovered in recent years) including St. John, Canaan, Jemseg, Aulac Rivers and Grand Lake (Sabine et al., 2004) but is uncommon to rare in Nova Scotia (Sydney River, Cape Breton Co.- Clarke and Rick, 1964) with populations small and/or declining (Metcalfe-Smith and Cudmore-Vokey, 2004). Davis (1999) narrowed distribution in the maritime provinces to only the Bay of Fundy/ Gulf of Maine drainage except for the Sydney River.

Population Size: >1,000,000 individuals
Population Size Comments: Typically, this species is found in low densities across its range. In Maine and Massachusetts, it is generally rare at most sites, but numerous (low hundreds of individuals) at a few sites. In a survey of 61 sites in the Pee Dee basin in South Carolina, only 3 sites (Great Pee Dee River and Little Pee Dee River) although typical slackwater habitats were not surveyed primarily (Catena Group, 2006).

Number of Occurrences with Good Viability/Integrity: Some (13-40)
Viability/Integrity Comments: Some healthy populations exist in Maine in the lakes and rivers of the lower Kennebec and Penobscot River drainages (Nedeau et al., 2000). Massachusetts also harbors some significant populations in the southeastern part of the state (J. Cordeiro, pers. obs., January 2007). Globally, it appears that New Brunswick harbours a globally significant population (Metcalfe-Smith and Cudmore-Vokey, 2004).

Overall Threat Impact: Unknown
Overall Threat Impact Comments: Anecdotal observations (J. Cordeiro, pers. comm., 2007) suggest that this species is sensitive to channel modification, pollution, sedimentation and low oxygen conditions. Likely threats include dams and other impoundments, channelization and dredging. Although found in close proximity to tidal areas, it is not tolerant of salinity.

Short-term Trend: Decline of 10-50%
Short-term Trend Comments: In New York (Hudson River) it has declined considerably since the introduction of the zebra mussel (Strayer and Jirka, 1997), possibly to the point of extirpation. The species has been extirpated from Pennsylvania where it formerly occurred in the Delaware basin (Bogan, 1993; Spoo, 2008) in the lower Delaware River and nearby lowlands including the Schuylkill and Wissahickon Creek (Ortmann, 1919). It seems to be declining throughout its range, particularly in the northeast where it is often scarce where it is found and populations are in decline (Nedeau et al., 2000), including parts of Canada such as Nova Scotia (Metcalfe-Smith and Cudmore-Vokey, 2004). Declines continue in the Connecticut River watershed (Nedeau, 2008) and Merrimack River watershed in New England.

Long-term Trend: Decline of 30-50%

Intrinsic Vulnerability: Not intrinsically vulnerable

Environmental Specificity: Moderate. Generalist or community with some key requirements scarce.
Environmental Specificity Comments: This species inhabits ponds, canals, and slow-moving sections of rivers; including artificial impoundments. It is usually found in water bodies close to, but not necessarily connected, to the ocean (Johnson, 1970; Nedeau et al., 2000). It is found in a variety of substrates, including silt, sand, gravel, cobble, and occasionally clay.

Other NatureServe Conservation Status Information

Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) This species is found along the Atlantic coastal plain from Cape Breton, Nova Scotia, to the Savannah River, Georgia (Johnson, 1970).

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 CT, DC, DE, GA, MA, MD, ME, NC, NJ, NY, PA, RI, SC, VA
Canada NB, NS

Range Map
No map available.

U.S. Distribution by County Help
State County Name (FIPS Code)
CT Hartford (09003), Middlesex (09007), New London (09011)
DE Kent (10001), Sussex (10005)
GA Bulloch (13031)*, Screven (13251)*
MA Barnstable (25001), Bristol (25005), Essex (25009)*, Hampden (25013), Hampshire (25015), Plymouth (25023)
MD Cecil (24015), Harford (24025), Kent (24029)*, Montgomery (24031)*, Prince Georges (24033)*
NC Bertie (37015), Chowan (37041), Columbus (37047), Edgecombe (37065), Gates (37073), Halifax (37083), Hertford (37091), Martin (37117), Northampton (37131), Pitt (37147), Vance (37181), Warren (37185), Washington (37187)
NJ Burlington (34005), Camden (34007), Cumberland (34011), Gloucester (34015), Hunterdon (34019), Mercer (34021), Middlesex (34023)*, Salem (34033), Somerset (34035)*
NY Albany (36001)*, Columbia (36021), Rensselaer (36083)*, Ulster (36111)
PA Bucks (42017)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
01 West Branch Penobscot (01020001), East Branch Penobscot (01020002), Piscataquis (01020004), Lower Penobscot (01020005), Lower Kennebec (01030003), Lower Androscoggin (01040002), St. George-Sheepscot (01050003), Merrimack (01070002)+, Middle Connecticut (01080201)+, Lower Connecticut (01080205)+, Farmington (01080207)+, Cape Cod (01090002)+, Narragansett (01090004)+, Pawcatuck-Wood (01090005)*, Housatonic (01100005)*
02 Hudson-Hoosic (02020003)+*, Middle Hudson (02020006)+, Hudson-Wappinger (02020008), Raritan (02030105)+*, Middle Delaware-Musconetcong (02040105)+, Crosswicks-Neshaminy (02040201)+, Lower Delaware (02040202)+, Schuylkill (02040203)*, Cohansey-Maurice (02040206)+, Broadkill-Smyrna (02040207)+, Lower Susquehanna (02050306)+, Upper Chesapeake Bay (02060001)+, Chester-Sassafras (02060002)+, Gunpowder-Patapsco (02060003)+, Nanticoke (02060008), Conococheague-Opequon (02070004), Middle Potomac-Catoctin (02070008)+*, Middle Potomac-Anacostia-Occoquan (02070010)+, Lower Potomac (02070011), York (02080107), Western Lower Delmarva (02080109)+, Anacostia River (02140205)+*
03 Middle Roanoke (03010102)+, Roanoke Rapids (03010106)+, Lower Roanoke (03010107)+, Ghowan (03010203)+, Meheriin (03010204)+, Upper Tar (03020101)+, Lower Tar (03020103)+, Pamlico (03020104), Middle Neuse (03020202)*, Lower Neuse (03020204)*, Lower Pee Dee (03040201), Waccamaw (03040206)+, Middle Savannah (03060106)*, Lower Savannah (03060109)*, Lower Ogeechee (03060202)+*
TA TA-53 (TA-53)+*
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
Basic Description: a freshwater mussel
Reproduction Comments: This species is a long-term brooder as eggs are fertilized in late summer and glochidia are released the following spring. The only confirmed fish host for this species is white perch (Morone americana) (Wick and Huryn, 2003).
Habitat Type: Freshwater
Non-Migrant: N
Locally Migrant: N
Long Distance Migrant: N
Riverine Habitat(s): CREEK, Low gradient, MEDIUM RIVER, Pool
Lacustrine Habitat(s): Shallow water
Special Habitat Factors: Benthic
Habitat Comments: This species inhabits ponds, canals, and slow-moving sections of rivers; including artificial impoundments. It is usually found in water bodies close to, but not necessarily connected, to the ocean (Johnson, 1970; Nedeau et al., 2000). It is found in a variety of substrates, including silt, sand, gravel, cobble, and occasionally clay.
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 (jay_cordeiro@natureserve.org) 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: 23Dec2011
NatureServe Conservation Status Factors Author: Cordeiro, J. (2011); Morrison, M. (2000)
Element Ecology & Life History Edition Date: 23Dec2011
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).

  • Alderman, J.M. and J.D. Alderman. 2009. Chowan River freshwater mussel survey. Report prepared for Citizens Against OLF by Alderman Environmental Services, Pittsboro, North Carolina. 56 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.

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


  • Cordeiro, J. 2000. Status of the tidewater mucket, Leptodea ochracea (Say, 1817) (Bivalvia: Unionidae), in Halfway Pond, Massachusetts, USA. The Nautilus, 114(2): 80-83.

  • Cordeiro, J. 2003b. Unio ochraceus Say, 1817 (currently Ligumia ochracea; Mollusca, Bivalvia): proposed precedence of the specific name over Mytilus fluviatilis Gmelin, 1791. Case 3223. Bulletin of Zoological Nomenclature, 60(1): 20-22.

  • Counts, C.L., III, T.S. Handwerker, and R.V. Jesien. 1991. The naiades (Bivalvia: Unionidea) of the Delmarva Peninsula. American Malacological Bulletin, 9(1): 27-37.

  • Davis, C. Abbott. 1905. The Unios of New England. Roger Williams Park Museum, Bulletin No. XII, Providence, RI. C. Abbott Davis, unpaginated.

  • Hanson, J.M. and A. Locke. 2001. Survey of freshwater mussels in the Petitcodiac River drainage, New Brunswick. The Canadian Field-Naturalist 115:329-340.

  • Haskins, J., et. al. 1992-1996. Freshwater Mussel Surveys. Funded by the U.S. Fish & Wildlife Service and ME Department of Inland Fisheries & Wildlife (MDIFW). Coordinated by MDIFW (Endangered Species Group, Bangor). Surveys ongoing.

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

  • International Commission on Zoological Nomenclature (ICZN). 2005. Opinion 2092 (CAse 3223). Unio ochraceus Say, 1817 (currently Ligumia ochracea; Mollusca, Bivalvia): specific name given precedence over that of Mytilus fluviatilis Gmelin, 1791. Bulletin of Zoological Nomenclature 62(1): 32-33.


  • Johnson, R.I. 1984. A new mussel, Lampsilis (Lampsilis) fullerkati (Bivalvia: Unionidae) from Lake Waccamaw, Columbus County, North Carolina, with a list of the other unionid species of the Waccamaw River system. Occasional Papers on Molluscs, 4(63): 305-319.

  • 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.

  • Lermond, N.W. 1909. Shells of Maine. Thomaston, ME. 46 p.

  • Letson, E. J. 1905. Checklist of the Mollusca of New York. Bulletin. No. 88. New York State Museum, Albany, NY.

  • 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.

  • Morrison, J. P. E. 1975. Maryland and Virginia mussels of Lister. Bulletin of the American Malacological Union, Inc. 1974: 36-39.

  • Morrison, J.P.E. 1976. Species of the genus Uniomerus. Bulletin of the American Malacological Union, 1976: 10-11.

  • 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. 2008. Freshwater Mussels and the Connecticut River Watershed. Connecticut River Watershed Council, Greenfield, Massachusetts. 132 pp.

  • Nylander, Olof O. 1943. The Lymnaeidae of Northern Maine and Adjacent Canadian Provinces and Notes on Anson Allen and His Collection. The Maine Bulletin. University of Maine Studies, Second Series No. 58, 46(2). University Press, Orono. 67 p.

  • Porter, H.J. and K.J. Horn. 1983. Habitat distribution of sympatric populations of selected lampsiline species (Bivalvia: Unionoida) in the Waccamaw drainage of eastern North and South Carolina. American Malacological Bulletin, 1: 61-68.

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



  • Smith, D.G. 2000b. On the taxonomic placement of Unio ochraceus Say, 1817 in the genus Ligumia (Bivalvia: Unionidae). The Nautilus 114(4):155-160.

  • Spoo, A. 2008. The Pearly Mussels of Pennsylvania. Coachwhip Publications: Landisville, Pennsylvania. 210 pp.

  • Stiven, A. and J. Alderman. 1992. Genetic similarities among certain freshwater mussel populations of the Lampsilis genus in North Carolina. Malacologia, 34(1-2): 355-369.

  • 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.

  • 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.

  • Strayer, David L. and Lane C. Smith. 1996. Relationships between zebra mussels (Dreissena polymorpha) and Unionid clams during the early stages of the zebra mussel invasion of the Hudson River. Freshwater Biology 36: 771-779.

  • 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.

  • 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.

  • Wick, P.C. and A.D. Huryn. 2003. PL 31. Fish hosts and population demographics of Lampsilis cariosa and Leptodea ochracea (Unionidae) in Maine. Meeting Program and Abstracts of the 3rd Biennial Symposium of the Freshwater Mollusk Conservation Society, March 16-19, 2003, Durham, North Carolina. 56 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.

References for Watershed Distribution Map
  • 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. 1963. Some new records of naiades from eastern North America. Sterkiana 9:39.

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

  • 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.

  • 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.

  • 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.

  • 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: http://cbc.amnh.org/mussel/.

  • Cordeiro, J. 2004. Freshwater mussels in Rhode Island: Part 2. Diversity and distribution. Rhode Island Naturalist, 11(1): 4-8.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • Sabine, D.L., S. Makepeace, and D.F. McAlpine. 2004. The yellow lampmussel (Lampsilis cariosa) in New Brunswick: a population of significant conservation value. Northeastern Naturalist, 11(4): 407-420.

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

  • 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.

  • 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.

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