> Goniobasis catenaria catenaria (Say 1822)
    "Elimia" catenaria

> Habitat & distribution
Populations of the typical form of G. catenaria inhabit rivers and streams of the piedmont and upper coastal plain from southern Virginia (Hoffman 1996) to Georgia.  G. catenaria catenaria does not occur in acidic or in nutrient-poor waters, and seems to require at least some rock substrate.  Thus it is not found in the slow coastal plain rivers, nor in the (many) southeastern streams with high sediment loads.  Its present spotty distribution (especially in South Carolina) may be a remnant of a much broader distribution prior to agriculture (Dillon & Keferl 2000). 

> Ecology & Life history
Although there have been no detailed studies of G. catenaria catenaria life history, I imagine that two years are required for maturity, and that several years of iteroparous reproduction can be expected thereafter, as is the case for pleurocerids generally (Dazo 1965).  This is life cycle G of Dillon (2000: 156 - 162).  The Georgia Goniobasis populations studied by Nelson & Scott (1962), Krieger & Burbanck (1976), and Krieger (1977) are all referable to G. catenaria (see below) and all seem restricted to scattered rocky shoals isolated by long stretches of inhospitable silt.  Where they reach high densities, however, grazing by pleurocerid populations can have a significant effect on energy flow in streams (Dillon 2000: 86 - 91).

> Taxonomy & Systematics
The type locality of G. catenaria ("St. Johns, Berkeley") must have been Eutaw Springs, sadly now drowned by Lake Marion.  The viable G. catenaria catenaria population nearest Eutaw Springs today inhabits Cedar Creek, a tributary of the Broad River about 12 km N of Columbia.  Dillon & Reed (2002) reported that the level of genetic divergence between the Columbia population and eight other G. catenaria populations sampled from North Carolina into Georgia was roughly comparable to the better-studied G. proxima.

Mihalcik & Thompson (2002) proposed that the range of G. catenaria is attenuated at the South Carolina border, and that Georgia streams are inhabited by a great variety of other Goniobasis species, largely endemic, not distinguishable to our eyes from G. catenaria.  The allozyme survey of Dillon & Robinson (in review) has demonstrated, however, that the range of G. catenaria does indeed extend across Georgia, to include all major Atlantic drainages as well as the Chattahoochee/Flint of the Gulf.  Synonyms of G. catenaria include albanyensis, boykiniana, caelatura, darwini, mutabilis, postelli, suturalis, and viennaensis (see also Chambers 1990).  Recently it has been pointed out that the nomen G. caelatura, although typically associated with Goniobasis populations of NW Georgia and Alabama, was first applied by its author (Conrad) to a population from the Savannah River (Thompson 2000).  This appears to be a junior synonym of catenaria as well.

Burch resurrected the name "Elimia" to include catenaria and approximately 80 other pleurocerid species traditionally assigned to Goniobasis (Lea 1862).  But Elimia (H. & A. Adams 1854) is a composite group, explicitly rejected by Tryon, Walker, Pilsbry and Goodrich (Dillon 1989).  See essay below.

> Essay
See my 28Sept04 post to the FWGNA web site for a review of the Goniobasis/Elimia taxonomic controversy.

> Pretty Photo
of living G. catenaria catenaria, courtesy of Chris Lukhaup.

>Maps of Goniobasis distribution
Click the small map to enlarge it, or download the state-specific PDFs



North Carolina (PDF)

South Carolina (PDF)

Georgia (PDF)

> References
Chambers, S. (1990) The genus Elimia (= Goniobasis) in Florida (Prosobranchia: Pleuroceridae). Walkerana, 4, 237-70.  Dazo, B. C. (1965)  The morpholoogy and natural history of Pleurocera acuta and Goniobasis livescens (Gastropoda: Cerithiacea: Pleuroceridae).  Malacologia 3: 1 - 80.  Dillon, R., T. Jr. (1989)  Karyotypic evolution in pleurocerid snails: I. Genomic DNA estimated by flow cytometry. Malacologia, 31: 197-203.  Dillon, R. T., Jr. (2000)  The Ecology of Freshwater Molluscs. Cambridge, Cambridge University Press.  509 pp.  Dillon, R. T., Jr. & R. C. Frankis (2004)  High levels of mitochondrial DNA sequence divergence isolated populations of freshwater snails of the genus Goniobasis.  Am. Malac. Bull.  19: 69-77.  Dillon, R. T., Jr. & Keferl, E. (2000) A survey of the pleurocerid gastropods of South Carolina.  In Freshwater Mollusk Symposia Proceedings, Part II, eds. Tankersley, Warmolts, Watters, Armitage, Johnson & Butler, pp. 153 - 160.  Columbus: Ohio Biological Survey.  Dillon, R. T., Jr. & Reed, A. (2002) A survey of genetic variation at allozyme loci among Goniobasis populations inhabiting Atlantic drainages of the Carolinas.  Malacologia 44: 23 - 31. Dillon, R. T., Jr. & Robinson, J. D. (in review) Genetic relationships among populations of Goniobasis ("Elimia") from central Georgia. Goodrich, C. (1942) The Pleuroceridae of the Atlantic coastal plain. Occas. Pprs. Mus. Zool. Univ. Mich., 456, 1-6.  Hoffman, R. L. (1996)  Occurrence of the costate riversnail, Oxytrema catenaria (Say), in Virginia. Banisteria, 7: 49-50.  Krieger, K. (1977)  Morphological and electrophoretic evidence of population relationships in stream snails of the family Pleuroceridae (Prosobranchia). Ph.D. Diss, Atlanta, Ga., Emory University.  Krieger, K. & W. Burbanck (1976)  Distribution and dispersal mechanisms of Oxytrema (=Goniobasis) suturalis Hald. (Gastropoda:Pleuroceridae) in the Yellow River, Georgia, U.S.A.  Am. Midl. Natur., 95: 49-63.  Mihalcik, E. R. & F. G. Thompson (2002) A taxonomic revision of the freshwater snails referred to as Elimia curvicostata, and related species.  Walkerana 13: 1 - 108.  Nelson, D., & D. Scott. (1962)  Role of detritus in the productivity of a rock-outcrop community in a piedmont stream. Limnol. & Oceanog., 7: 396-413.  Thompson, F. G. (2000)  Freshwater snails of the genus Elimia from the Coosa River System, Alabama.  Walkerana 11(25): 1 – 54.