Elliptio incrassata (Lea, 1843)

1. Murder Creek, Conecuh Co., AL - 70 mm
2. Sepulga River, Conecuh Co., AL - 61 mm

Type locality: Chattahoochee River, near Columbus, Georgia.

Range: Escambia, Choctawhatchee, Apalachicola, Chipola, and St Marys River systems.

Remarks: In the south lives this crassidens-like taxon that lives in creeks as well as rivers. True crassidens to the north is almost exclusively a big river species. It could be argued that the species illustrated here is but a headwater form of crassidens. However, both crassidens and incrassata may be found together in the St Marys River. Because of this, and the consistent differences between the two, I recognize them as distinct.

Incrassata is usually more compressed and elongate, often nearly rectangular in profile, with a much lower umbo. It is never rayed. The nacre is light purple, often with a flush of salmon under the beaks.

In the Apalachicola River this species assumes a peculiar elongated, hooked form in old individuals.