Pleurobema taitianum, commonly known as the heavy pigtoe or Judge Tait's mussel, is a species of freshwater mussel, an aquatic bivalve mollusk in the family Unionidae (river mussels).
Taxonomy The species was originally described as Unio taitianus by Isaac Lea in 1834. It is classified within the genus Pleurobema in the family Unionidae. Synonyms include Margarita (Unio) taitianus, Pleurobema aldrichi, Pleurobema tombigbeanum, and Unio tahetianus.
Description The heavy pigtoe is a bivalve mollusk approximately 50 mm long, 45 mm high, and 30 mm wide. The shell is brown to brownish-black, obliquely triangular, and inflated, with narrowly pointed beaks directed forward. It features a very shallow but distinct furrow, pink-tinted nacre (inner shell layer), and shallow beak cavities.
Distribution and Habitat This species is endemic to the United States. Historically, it was found in the Tombigbee, Alabama, Coosa, Cahaba, and possibly the Black Warrior river systems. Currently, its range is restricted to the Alabama/Coosa River system. The species may already be extinct, as no evidence of recruitment (young individuals) was found in a 2010 survey.
Conservation Status
- IUCN Red List: Endangered (2012 assessment)
- NatureServe: Critically Imperiled
- U.S. Endangered Species Act: Federally listed as Endangered (1987)
The species received federal protection in 1987 after construction of the Tennessee–Tombigbee Waterway isolated it in a bypassed meander of the Tombigbee River. At the time of listing, it was also believed to survive in the Buttahatchie, East Fork Tombigbee, and Sipsey rivers. Threats included habitat alteration from U.S. Army Corps of Engineers improvement projects and water temperature changes from diversion of Bull Mountain Creek into a warm-water canal.
