Volume 5 of the FWGNA series expands our continental survey of freshwater snails into the rivers, lakes, ponds, and streams of the Ohio drainage, together with its primary tributaries the Cumberland and the Tennessee. Our database of 9,370 records, sampled from approximately 4,250 distinct sites, was drawn from museums (24%), state natural resource agencies (34%) and personal collections. We document 80 species and 19 subspecies of freshwater gastropods in this malacologically rich region. For each we provide:
- A dichotomous key for identification.
- Full color figures.
- Range maps.
- Notes on habitat, ecology, and reproductive biology.
- Systematic and taxonomic updates to modern standards.
Our complete FWGNA database, updating records from Atlantic drainages and combining with our fresh data from the Interior, now contains 22,044 records documenting 107 species of freshwater gastropods, with 21 subspecies. Here we offer a new continent-scale biogeographic analysis, dividing records into North Atlantic, South Atlantic, Ohio, and Tennessee/Cumberland subsets. Our analysis suggests that natural selection has been more important in the evolution of freshwater pulmonate snails than gene flow restriction, but that gene flow restriction has been more important in the evolution of freshwater prosobranch snails than natural selection.
In Volume 1 we pioneered a new method to rank freshwater gastropods by incidence categories for the purposes of conservation, based on the work of K. J. Gaston. Here in Volume 5 we update that system to include all 107 species across all regions, re-assigning incidence ranks as necessary. Three new species of cave-dwelling hydrobioid snails: Fontigens hershleri, F. benfieldi, and F. davisi, are described in the appendix.