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Description
This species was originally decribed as Unio decoratus by Isaac Lea in 1852. The Carolina heelsplitter is a medium-sized mussel that has an ovate, trapezoid-shaped shell. The largest known specimen of the species measures 114.8 millimeters in length. The shell is yellowish, greenish brown to dark brown in color and younger specimens have greenish brown or black rays. The nacre is pearly white to bluish-white, grading to orange in the area of the umbo. In older specimens, the entire nacre may be a mottled pale orange. The lateral teeth are well developed but thin and rather delicate. The left valve has two blade-like pseudocardinal teeth and the right valve has one. The left valve may also have an interdental projection.

Distribution (see map)
The complete historic range of the species is unknown, but available information indicates it was once fairly widely distributed in the Catawba and Pee Dee river basins in North Carolina and Pee Dee and Savannah Rivers basins (and possibly the Saluda River Basin) in South Carolina. Prior to 1987, the Carolina heelsplitter had not been found since the mid-19th century. There are only six known remaining populations of this species-two in North Carolina and four in South Carolina. The North Carolina populations are located in Goose Creek (Pee Dee River Basin) and Waxhaw Creek (Catawba River Basin) in Union County. In South Carolina, there is one population in the Lynches River, including Flat Creek (Pee Dee River Basin), one in Gills Creek (Catawba River Basin), one in Cuffytown Creek (Savannah River Basin), and another population in the Turkey Creek drainage (Savannah River Basin). Distribution by County in North Carolina Summary: Pee Dee River Basin: Union Co. (Goose Cr. Subbasin, and Lynches River Subbasin-water flows into occupied South Carolina habitat), Mecklenburg Co. (Goose Cr. Subbasin); Catawba River Basin: Union Co. (Waxhaw Cr. Subbasin). NOTE: All headwater areas that flow into these occupied habitats should receive special management.

Habitat Preferences
Historically, the Carolina heelsplitter was reported from small to large streams and rivers as well as ponds. The ponds referred to in historic records are believed to have been mill ponds on small streams. In North Carolina, this species is found in a variety of substrates usually near stable, well-shaded stream banks. However, Turkey Creek, South Carolina specimens have also been found in the main channel of the stream, in relatively clean substrate comprised of sand, gravel, and cobble. The stability of stream banks appears to very important to the species.

Life History
Because of its rarity, little is known about the life history of the Carolina heelsplitter. No fish have been identified as hosts (fish host) for this species.