Distribution: Alasmidonta marginata is distributed across the Great Lakes and St. Lawrence River drainage in Canada and as far east as the Susquehanna and St. Lawrence River drainages in New York. Occurs in many areas of the Mississippi River drainage including the Ohio River drainage as far east as Virginia, in the Mississippi River as far west as the Upper Minnesota River system in Minnesota, and as far south as the Tennessee River system in Alabama. This species is likely extirpated from main channels of the Tennessee and Cumberland rivers but is most abundant in Ohio River tributaries in Illinois, Indiana, and Ohio. In Oklahoma, historical records exist from the Illinois and Neosho rivers, but the species was last observed in 1982 and may no longer occur in the state.

Life History and Ecology: Usually occurs at low abundance. Typically occurs in small, shallow streams with a moderately fast current and fine gravel and sand. Long-term brooder that reportedly infects and metamorphoses on white sucker, northern hog sucker, shorthead redhorse, and warmouth. Periodic life history strategy.

Special Status: Considered a species of special concern by the American Fisheries Society

Shell Description: click here for shell description