Illinois Natural History Survey - University of Illinois

Potamilus alatus (Say, 1817)

Pink heelsplitter


Potamilus alatus, INHS 8049Potamilus alatus, INHS 8049. Mackinaw River, McLean County, Illinois.
Length: 3.8 inches (9.7 cm).


Other common names Purple heelsplitter, pancake, hatchet-back.

Key characters An elongate and rectangular shell, well-developed posterior wing, dark green to dark brown, with a purple or pink nacre.

Similar species Bleuferwhite heelsplitterpink papershell.

Description Shell large, elongate, laterally compressed and somewhat rectangular, thin in young shells to moderately thick in older individuals. Anterior end rounded, posterior end bluntly squared or truncated.Potamilus alatus distribution Umbos flattened and only slightly elevated above the hinge line. Beak sculpture of three or four concentric ridges, visible only in small shells. Large wing present posterior to the umbos. Shell smooth, dark green or brown, becomingblack in old individuals. Young shells typically marked with dark green rays that become fainter with age. Length to 8 inches (20.3 cm).

Pseudocardinal teeth small, roughened, thin and divergent; two in the left valve, two in the right. Lateral teeth long, thin, and straight to slightly curved. Beak cavity shallow. Nacre usually purple or pinkish purple, rarely white; highly iridescent.

Habitat Medium to large rivers in mud or mixed mud, sand, and gravel.

Status Widespread and relatively common.

Back Forward Species | Table of Contents

Illinois Natural History Survey

1816 South Oak Street, MC 652
Champaign, IL 61820

Terms of use. Email the Web Administrator with questions or comments.

© 2019 University of Illinois Board of Trustees. All rights reserved.
For permissions information, contact the Illinois Natural History Survey.

Staff Intranet