Rayed Bean (Villosa fabalis)

The rayed bean is one of our smallest freshwater mussels, reaching a total length of less than 4 cm. This species is easily overlooked since it is often found deeply buried in sand or gravel among the roots of aquatic plants. It is extremely rare globally. Although it was once more widespread in southern Ontario, the rayed bean is now found only in the East Sydenham River. Its distribution generally overlaps that of the northern riffleshell.

The Rayed Bean is sensitive to pollution from municipal, industrial, and agricultural sources. Siltation, habitat perturbation and impoundment of rivers have also likely destroyed much of the habitat for this species over the last century. More recently the Zebra Mussel (Dreissena polymorpha) has devastated some Rayed Bean populations in the Great Lakes. Access to suitable host species may also threaten this species.

rayed bean