North Carolina Wildlife Resources Commission

Cumberland Bean Pearlymussel (Conrad, 1834)

Scientific Name: Villosa trabalis

Classification:  State Extirpated

Photo Credit: NCWRC
   

Interior

 

Exterior 

NOTE: Hover over the bold words for definitions or see the Glossary.

This species was described by Conrad in 1834 from the Flint River in Alabama. The Cumberland bean is a small species with solid, elongate, inflated, oval valves. Female shells reach a slightly larger size than males, attaining a maximum length of about 55 mm. Beaks are high and situated near the anterior end where the shell is thickest. The periostracum is somewhat glossy and often appears dark greenish-black in older specimens. Young specimens may be olive-green or yellowish-brown with numerous wavy, dark green rays. The nacre color is a bluish white or white with a bluish iridescence posteriorly. The left valve has two solid triangular pseudocardinal teeth, a narrow interdentum and two long, straight, relatively heavy lateral teeth. The right valve has three pseudocardinal teeth and a single lateral tooth (Parmalee and Bogan 1998).

 

Shell Anatomy

 
Historically, the Cumberland bean was restricted to tributary streams of the Tennessee and Cumberland rivers and was most abundant in the Cumberland system. Historic records for the species exist for the Tennessee River, South Chickamauga Creek, Paint Rock River, Flint River, Hiwassee River, Clinch River, Cumberland River, Buck Creek, Obey River, Rockcastle River, Laurel Fork of the Rockcastle River, and Beaver Creek. Populations of the species still exist in Cumberland River tributaries in Kentucky and Tennessee, and the Hiwassee River downstream of Apalachia Dam in Tennessee. This species is thought to be extirpated from North Carolina.

 


The Cumberland bean typically inhabits medium-sized streams to small rivers (5-20m width). It prefers gravel and sand/gravel substrates in riffle areas with moderate to fast current. This species frequently occurs in the transition zone between gravel and sand substrates (Clarke 1981).

This species is a bradytictic breeder. Probable fish hosts that have been identified for the Cumberland bean include the following darter species: fantail, stripetail, sooty, barcheek, striped and Tennessee snubnose (Layzer and Anderson 1991, 1992).

 

General Life History For Mussels