Plethobasus cicatricosus
Photo: Wikimedia Commons (CC) via https://en.wikipedia.org/wiki/Plethobasus_cicatricosus
Overview
Plethobasus cicatricosus, the white warty-back pearly mussel or white wartyback, is a species of freshwater mussel in the family Unionidae, the river mussels. Once widely distributed in the Ohio, Cumberland, and Tennessee River systems in the United States, its range has declined dramatically to the point of near-extinction. It is a federally listed endangered species of the United States.
The white wartyback mussel faces severe population declines primarily due to dam construction and river channelization that have altered natural flow regimes and sediment transport patterns essential for reproduction. Water pollution from agricultural runoff and industrial discharge has degraded water quality, while invasive zebra mussels compete for resources and attach to native shells, often suffocating them. The species' complex reproductive cycle, requiring specific fish hosts for larval development, makes it particularly vulnerable to disruptions in aquatic ecosystems.
Habitat
The white wartyback inhabits medium to large rivers with stable gravel, sand, and mud substrates in areas with moderate to swift currents. It requires clean, well-oxygenated water and depends on specific fish species as hosts for its parasitic larval stage.
