Page last updated
Thu 3 September 2025

The Freshwater Mussels (Unionoida) of the World (and other less consequential bivalves)

FM(U)otW(aolcb) is the web version of the MUSSEL Project Database. Follow the links to browse the data or use the custom Google search field. Either way, you win!

North America

The region includes all of North America, north of the Mexican Plateau. It is the second-most most species-rich region in the world, with 0 species (0 genera). The families represented are Unionidae and Margaritiferidae.

North America is composed of five subregions. The Canadian Interior Subregion drains to southern and eastern Hudson Bay and the Arctic (NA1; 0 gen., 0 spp., 0 endemic) The Mississippi-Great Lakes Subregion (NA2; 0 gen., 0 spp., 0 endemic) which includes the Mississippi Basin and the adjacent, formerly glaciated areas of the Great Lakes. The streams draining directly to the Atlantic comprise the Atlantic Slope Subregion (NA3; 0 gen., 0 spp., 0 endemic), which extends from the glaciated portions of eastern Canada and the USA, south to Georgia. The Gulf-Florida Subregion (NA4; 0 gen., 0 spp., 0 endemic) is a real hot-spot of freshwater mussel diversity that occurs from the Rio Grande Basin in Mexico, east to peninsular Florida. West of the continental divide is the Pacific Subregion (NA5; 0 gen., 0 spp., 0 endemic). The Pacific Subregion shares closer affinities with East Asia than the rest of North America.

Endemic species are marked with an asterisk (*).

Canadian Interior (NA1)

Mississippi-Great Lakes (NA2)

Atlantic Slope (NA3)

Gulf of Mexico-Florida (NA4)

Pacific (NA5)