Please Note: Red text is defined in the Glossary

Description
Say described this species in 1817 from the Schuylkill River in Pennsylvania. The periostracum is smooth, shiny, and usually yellow with some brownish freckling or patches on some surface areas. Rays may be present - usually on the posterior slope but rarely may extend toward the anterior end, resulting in over half the shell being rayed. Females are obovate or subovate resulting in a rather short high shape. Males are elongate and elliptical. Shells may reach 130 mm in length (Johnson 1970). The nacre is usually white to bluish white. Britton and Fuller (1979) and Fuller and Bereza (1974) add that a distinguishing characteristic of female yellow lampmussels is the development of the mantle, anterior to a larger darkly pigmented "eyespot," into a strongly developed flap of tissue on each mantle lobe. Also, the ventral margin of the marsupium is darkly pigmented (Britton and Fuller 1979).

Distribution (see map)
The yellow lampmussel is found from the lower Ottawa River, Canada eastward to the Sydney River, Nova Scotia then south to the Ogeechee River Drainage Basin in Georgia (Johnson 1970). At one time this species probably ranged throughout most of the Atlantic Slope drainages in North Carolina; however, historical records provided by Johnson (1970) come from the Cooper-Santee, Waccamaw, Cape Fear, neuse, Pamlico, and Chowan drainages. It appears that this species has been recently extirpated from the Black River in Sampson, Bladen, and Pender counties and from Ruin Creek in Vance County.

Distribution by County: Pee-Dee River Basin: Montgomery Co. (Little River Basin). Waccamaw River Basin: Columbus Co. (Lake Waccamaw). Cape Fear River Basin: Randolph Co. (Deep River); Moore (Deep River); Chatham (Deep River); Lee Co. (Deep River); Harnett Co. (Cape Fear River); Cumberland counties (Cape Fear River). Neuse River Basin: Person Co. (Flat River Subbasin), Durham Co. (Flat and Little river subbasins), Orange Co. (Eno River Subbasin), Johnston Co. (Little River Subbasin). Tar River Basin: Granville Co. (Tar River Subbasin), Franklin Co. (Sandy Cr. Subbasin and Tar River), Nash Co. (Swift and Fishing creek subbasins and Tar River), Edgecombe Co. (Fishing Cr. Subbasin and Tar River), Halifax Co. (L. Fishing and Fishing creek subbasins). NOTE: All headwater areas that flow into these occupied habitats should receive special management.

Habitat Preferences
The yellow lampmussel can be found in many different habitats; however, it appears to slightly prefer the shifting sands downstream from large boulders in relatively fast flowing, medium sized rivers and medium to large creeks.

Life History
This species is considered to be bradytictic (Ortmann 1919, Alderman 1988). The alewife or another migratory fish has been suggested as the host fish for the yellow lampmussel (Johnson 1947). This may be true for some populations of this mussel species, but there must also be freshwater host(s), since this species can be found in isolated creeks and rivers in North Carolina.