FWGNA > Freshwater Gastropods of Virginia
Virginia (Atlantic)
The 102,671 km/sq enclosed by the Commonwealth of Virginia includes seven (Level III) US EPA ecoregions and four (Level 2) USGS hydrologic units - Mid Atlantic, South Atlantic, Tennessee and Ohio.

The survey of freshwater gastropods we report here is focused on the eastern 75% of the state only, draining from headwaters in the Ridge & Valley ecoregion eastward through the Blue Ridge, Piedmont and Coastal Plain to the Atlantic Ocean. The gastropod fauna of the New River and Big Sandy drainages is covered by the FWGO survey elsewhere on this site, and the fauna of the Tennessee drainages in the far SW corner of Virginia is covered by the FWGTN.

The published literature includes two previous statewide inventories of Virginia’s freshwater gastropod fauna, as well as several regional surveys. Prominent in the latter category are the surveys conducted in the coastal plain by Rehder (1949), in the James River Basin and Hanover County by Burch (1950, 1952), again in the James River by Clench and Boss (1967), in the Holston River by Stansbery (1972, Stansbery and Clench 1974a, 1974b, 1977), and in the New River by Dillon & Benfield (1982). Hershler and colleagues (1990) combined museum records together with field collections in their comprehensive review of the Fontigens species inhabiting Virginia and surrounding states. Beetle (1973) compiled a statewide checklist from museum records, which Stewart & Dillon (2004) included with their larger review of all published accounts and records of freshwater gastropods in the Commonwealth. 

Several species of freshwater snails have been originally described from Virginia type localities in the modern era. Somatogyrus virginicus was described from a population in the Rapidan River in Culpeper County (Walker 1904). Baker (1911) described the lymnaeid Stagnicola neopalustris from Orange County Virginia, although the species has not been subsequently collected. Hubricht (1957) described Fontigens orolibas from springs and cave streams in Shenandoah National Park, and Hershler et al. (1990) added F. morrisoni from Bath and Highland Counties. Holsingeria unthanksensis was described from a population inhabiting Unthanks Cave, in the Tennessee drainages of southwestern Virginia, by Hershler (1989).

Atlantic drainage sample sites

Virginia populations of freshwater gastropods have also served as models for basic research of an ecological or evolutionary nature. The distribution and abundance of Leptoxis populations in small tributaries of the James River has been studied by Miller (1985) and Stewart & Garcia (2002). Dillon has conducted extensive evolutionary studies of Goniobasis (now Pleurocera) populations from the southern and western regions of the state (Dillon & Davis 1980; Dillon 1986, 1988, 1989).

> Methods

The database here analyzed comprises 2,396 records (9Oct23).  A significant fraction (599 records) were contributed by the Virginia Department of Game and Inland Fisheries, either collected directly by DGIF personnel or by contractors for specific projects. A second set of 360 records were gathered by RTD from a review of the macrobenthic collections made by Virginia Commonwealth University biologists as a part of the INSTAR project.  An examination made by RTD of collections held by the VADEQ office in Glen Allen on 7/07 yielded 120 records, and a 1/2005 visit by RTD and BTW to the Virginia Museum of Natural History in Martinsville yielded 98 records.  

As the FWGNA project has expanded, we have been accorded the opportunity to examine the systematic collections of seven other national or regional museums, in addition to the VMNH: the National Museum of Natural History (Smithsonian), the Academy of Natural Sciences of Philadelphia, The Carnegie Museum of Natural History (Pittsburgh), the Delaware Museum of Natural History, the North Carolina Museum of Natural Sciences (Raleigh), the Georgia Museum of Natural History (Athens), and the Florida Museum of Natural History (Gainesville). Although the Virginia holdings of some of these other institutions have not been extensive, their curatorial staffs have always been most helpful.

The largest fraction of the records analyzed here (954 records) were added in field surveys conducted by RTD from 2002 to 2023 over all ecoregions, all subdrainages, and all counties, using standard qualitative techniques (Dillon 2006).  Click the image above to download a pdf map showing our sample sites.  No “absence stations” are mapped.  If freshwater gastropods were not collected at a site, then no record resulted.  Our entire 2,333 record database is available (as an excel spreadsheet) from the senior author upon request.

The taxonomy employed by the FWGNA project is painstakingly researched, well-reasoned and insightful.  But since the Virginia Division of Game and Inland Fisheries predominantly follows Turgeon et al. (1998), taxonomic differences do occur between VDGIF and the present web site.  First-time visitors looking for information about particular taxa might profitably begin their searches with a check for synonyms on our alphabetical index.


The 41 species and subspecies of freshwater gastropods we have confirmed from Atlantic drainages of Virginia (plus 5 unconfirmed) are figured in the FWGVA gallery and distinguished on the FWGVA dichotomous key.  Ecological and systematic notes for each species and subspecies are provided on dedicated pages, together with regional distribution maps.  Their distributions and abundances on a continental scale are analyzed in our sections on Biogeography and Synthesis

> Acknowledgements

We thank Dr. Len Smock, Drew Garey, and their colleagues at VCU for providing access to the INSTAR collections and hosting us graciously during our visits to Richmond, and Bill Shanabruch of the VADEQ in Glen Allen for similar courtesies.  Our appreciation is also due to Dr. Richard L. Hoffman of the VMNH for providing access to the collections under his care, as well as to Bob Hershler at the USNM, Gary Rosenberg, Paul Callomon and Amanda Lawless at the ANSP, Tim Pearce at the CMNH, Liz Shea at the DMNH, Art Bogan and Jamie Smith at the NCSM, Liz McGhee at the GMNH, and John Slapcinsky at the FMNH.  

The success of this project has in large part depended on the GIS and data analysis skills of Dr. Doug Florian, and the webmastery of Mr. Steve Bleezarde, to whom we offer our sincere thanks. This publication was completed with funds provided by the Virginia Department of Game and Inland Fisheries (VDGIF) through a State Wildlife Grant from the U.S. Fish and Wildlife Service.

> References

Ahlstedt, S.A. 1979. Recent mollusk transplants into the North Fork Holston River in southwestern Virginia. Bulletin of the American Malacological Union 1979:21-23.
Ahlstedt, S.A. 1991. Reintroduction of the spiny riversnail Io fluvialis (Say, 1825) (Gastropoda: Pleuroceridae) into the North Fork Holston River, Southwest Virginia and Northeast Tennessee. American Malacological Bulletin 8:139-142.
Baker, F.C. 1911. The Lymaeidae of North and Middle America, Recent and Fossil. Chicago Academy of Sciences Special Publication No. 3., Chicago, Illinois.
Beetle, D.E. 1973. A checklist of the land and freshwater mollusks of Virginia. Sterkiana 49:21-35.
Burch, J.B. 1950. Mollusks: In James River Project Committee of the Virginia Academy of Science, ed., The James River Basin, Past, Present, and Future., Virginia Academy of Science, Richmond, Virginia. Pp. 129-137.
Burch, J.B. 1952. Preliminary checklist of Mollusca of Hanover County, Virginia. Nautilus 66:60-63.
Clench, W.J. & K.J. Boss. 1967. Freshwater Mollusca from James River, VA and a new name for Mudalia of authors. Nautilus 80:99-102.
Dillon, R.T., Jr. 1986. Inheritance of isozyme phenotype at three loci in the freshwater snail, Goniobasis proxima: mother-offspring analysis and artificial introduction. Biochemical Genetics 24:281-290.
Dillon, R.T., Jr. 1988. Evolution of transplants between genetically distinct populations of freshwater snails. Genetica 76:111-119.
Dillon, R.T., Jr. 1989. Karyotypic evolution in pleurocerid snails. I. Genonomic DNA estimated by flow cytometry. Malacologia 31:197-203.
Dillon, R.T., Jr. 2006. Freshwater Gastropoda. pp 251 - 259 In The Mollusks, A Guide to their Study, Collection, and Preservation. Sturm, Pearce, & Valdes (eds.) American Malacological Society, Los Angeles & Pittsburgh.
Dillon, R.T., Jr. & E.F. Benfield 1982. Distribution of pulmonate snails in the New River of Virginia and North Carolina, U.S.A.: interaction between alkalinity and stream drainage area. Freshwater Biology 12:179-186.
Dillon, R.T., Jr., and G.M. Davis. 1980. The Goniobasis of southern Virginia and northwestern North Carolina: genetic and shell morphometric relationships. Malacologia 20:83-98.
Hershler, R. 1989. Holsingeria unthanksensis, a new genus and species of aquatic cavesnail from eastern North America. Malacological Review 22:93-100.
Hershler, R., J.R. Holsinger & L. Hubricht 1990. A revision of the North American freshwater snail genus Fontigens (Prosobranchia: Hydrobiidae). Smithsonian Contributions to Zoology 509:1-49.
Hubricht, L. 1957. New species of Fontigens from Shenandoah National Park. Nautilus 71:9-10.
Miller, C. 1985. Correlates of habitat favorability for benthic macroinvertebrates at five stream sites in an Appalachian Mountain drainage basin, USA. Freshw. Biol. 15: 709-733.
Rehder, H.A. 1949. Some land and freshwater mollusks from the coastal region of Virginia and North and South Carolina. Nautilus 62:121-126.
Stansbery, D.H. 1972. The mollusk fauna of the North Fork Holston River at Saltville, Virginia. Bulletin of the American Malacological Union 1971:45-46.
Stansbery, D.H. & W.J. Clench 1974a. The Pleuroceridae and Unionidae of the North Fork Holston River above Saltville, Virginia. Bulletin of the American Malacological Union 1974:33-36.
Stansbery, D.H. & W.J. Clench 1974b. The Pleuroceridae and Unionidae of the Middle Fork Holston River in Virginia. Bulletin of the American Malacological Union 1974:51-54.
Stansbery, D.H. & W.J. Clench 1977. The Pleuroceridae and Unionidae of the upper South Fork Holston River in Virginia. Bulletin of the American Malacological Union 1977:75-79.
Stewart, T.W. & R.T. Dillon, Jr. 2004. Species composition and geographic distribution of Virginia’s freshwater gastropod fauna: a review using historical records. American Malacological Bulletin 19:79-91.
Stewart, T. W. & J. E. Garcia. 2002. Environmental factors causing local variation in density and biomass of the snail Leptoxis carinata, in Fishpond Creek, Virginia. Am. Midl. Natur. 148: 172-180.
Turgeon, D. D. & 14 other authors. 1998. Common and Scientific Names of Aquatic Invertebrates from the United States and Canada: Mollusks.  American Fisheries Society Special Publication #26.  Bethesda, MD. 526 pp.
Walker, B. 1904. New species of Somatogyrus. Nautilus 17:133-142.