Winged Mapleleaf
Quadrula fragosa (Conrad)

Status: State Endangered (August 1, 1989). Federally Endangered (1991).

Occurence: Occurs only in the St. Croix River.

Aid to ID: Shell is square, thick, and yellowish-green to light brown with faint rays in smaller shells, becoming greenish-brown or dark brown in larger individuals. A pronounced wing is present posterior to the umbo with radiating rows of ridges. The beak sculpture has two rows of raised nodules that continue down the surface of the shell separated by a furrow. Anterior and posterior ends are squared or truncated. Pseudocardinal teeth are well developed and serrated. Laterals are long. Striated, and straight. The nacre is pearly white, iridescent posteriorly, Up to 4 inches (10.2 cm) long.

Habitat: Occurs in large rivers on a mixed sand and gravel bottom in water two meters or more in depth.

Management Considerations: Habitat destruction and river pollution have resulted in mussel declines. Protection of habitat and improvements in water quality along with restriction of dredging, impoundments, sand and gravel mining, and navigational improvements would benefit this species. The development of fish runways to facilitate the movement of host species through or around dams could also help to protect the winged mapleleaf. The U.S. Fish and Wildlife Service has developed a recovery plan for this species.

The content for this page was originally presented in the Endangered and Threatened Invertebrates of Wisconsin, a free publication available by contacting the Endangered Resources Program.