Freshwater Mussels On Georgia's List of Federally Protected Species

Kim D. Coder
Professor, Silvics/Ecology
Warnell School of Forest Resources
The University of Georgia

June, 1993

On April 16, 1993 eleven species of freshwater mussels were given protection under the Endangered Species Act. Nine of these mussel species have ranges that extend into northwest Georgia. Mussels are unsegmented invertebrates that produce a two piece shell with a pearl-like inner surface. Generically, many people call them clams or naiads.

The nine species with historic or current populations in Georgia include:

Common Name	Scientific Name	Protection Status	States
upland combshell	Epioblasma metastriata	endangered	AL, GA, TN
southern acornshell	Epioblasma othcaloogensis	endangered	AL, GA, TN
fine-lined pocketbook	Lampsilis altilis	threatened	AL, GA
Alabama moccasinshell	Medionidus acutissimus	threatened	AL, GA, MS
Coosa moccasinshell	Medionidus parvulus	endangered	AL,GA,TN
southern clubshell	Pleurobema decisum	endangered	AL,GA,MS,TN
southern pigtoe	Plerubema georgianum	endangered	AL, GA, MS, TN
ovate clubshell	Pleurobema perovatum	endangered	AL, GA, MS, TN
triangular kidneyshell	Ptychobranchus greeni	endangered	AL,GA,TN

Species Descriptions

Upland Combshell (Epioblasma metastriata)

Bivalve up to 2.4 inches in length. Male and female look distinctly different. External color is yellow-brown to tan sometimes with broken green lines or green spots. Could be known as Unio compactus or Unio metastriatus. Found in the Conasauga River in Georgia.

Southern Acornshell (Epioblasma othcaloogensis)

Bivalve up to 1.2 inches in length. Male and female appear distinctly different. External color is yellow with a smooth, shiny texture. Could be known as Unio othcaloogensis or Unio modicellus. Found in the upper Coosa River system streams.

Fine-lined Pocketbook (Lampsilis altilis)

Bivalve rarely exceeding 4 inches in length. External color is yellow-brown to black with fine lines on the underside. The inner surface of the shell is white. Could be known as Unio altilis, Unio clarkianus, or Unio gerhardtii. Found in the head waters of the Sipsey Fork (including Rush and Brushy Creeks) and North River of the Black Warrior River drainage, Tatum Creek in the Alabama River drainage, Little Cahaba River in the Cahaba River drainage, Conasauga River in the Coosa River drainage (one site in main channel), and Chewacla and Opintlocco Creeks in the Tallapoosa drainage. Species appears confined to creek habitats.

Alabama Moccasinshell (Medionidus acutissimus)

Bivalve up to 1.2 inches in length with a thin shell. External color is yellowish to brownish yellow with broken green lines. The inner surface of the shell is thin and translucent at the margins grading into a pink color elsewhere. Could be known as Unio acutissimus or Unio rubellinus. Found in the Luxapalila Creek, Buttahatchee and Sipsey Rivers in the Tombigbee River drainage, headwaters of the Sipsey Fork (Brushy and Rush Creeks) in the Black Warrior River drainage, and Conasauga River.

Coosa moccasinshell (Medionidus parvulus)

Bivalve rarely beyond 1.6 inches in length. The shell is thin and fragile. External color is yellow-brown to dark brown with fine green lines. The inner surface of the shell is blue, sometimes with dark pink spots. Could be known as Unio parvulus. Found in the Cahaba River, Sipsey Fork of Black Warrior River drainage, and Choccolocco Creek, Chatooga, Conasauga, and Little Rivers in the Coosa River drainage as well as the Coosa River itself.

Southern Clubshell (Pleurobema decisum)

Bivalve up to 2.8 inches long with a thick shell. External color is yellow to yellowish-brown sometimes with green lines or spots when young. Could be known as Unio decisus, Unio anaticulus, Unio crebrivittatus, or Unio pallidovulvus. Once found in every major stream system in Mobile River drainage except for the Mobile Delta. Now found in Bogue Chitto Creek in the Alabama River drainage, Buttahatchee, East Fork Tombigbee, and Sipsey Rivers in the Tombigbee River drainage, and Chewacla Creek in the Tallapoosa River drainage.

Southern Pigtoe (Pleurobema georgianum)

Bivalve occasionally exceeding 2.4 inches in length. External color is yellow to yellow-brown with many dark growth lines. Small specimens may have green spots at the growth lines near the hinge. The inner surface of the shell is white. Could be known as Unio georgianus. Once found in the Coosa River drainage. Now found in widely scattered areas of the Coosa River drainage and in the Conasauga River.

Ovate Clubshell (Pleurobema perovatum)

Bivalve rarely larger than 2.0 inches in length. External color is yellow to dark brown with occasional broad green lines. The inner surface of the shell is white. Could be known as Unio perovatus, Unio nux, Unio cinnamonicus, Unio pinkstoni, Unio concolor, Unio flavidulus, or Unio johannis. Found in Buttahatchee and Sipsey Rivers in the Tombigbee River drainage, Blackwater Creek and Locust Fork in the Black Warrior River drainage, and Chewacla Creek in the Tallapoosa River drainage.

Triangular Kidneyshell (Ptychobranchus greeni)

Bivalve reaching 4 inches in length. External color is pale yellow when young aging to yellow-brown and sometimes with fine, wavy or broken green lines. Could be known as Unio greenii, Unio brumbleyanus, Unio brumbyanus, Unio foremanianus, Unio woodwardius, Unio woodwardianus, Unio trinacrus, Unio flavescens, and Unio simplex. Found in the headwaters of the Sipsey Fork and Little Warrior River of the Black Warrior River drainage and in the Conasauga River in the Coosa River drainage.

All these mussels are found on stable gravel and sandy-gravel bottoms where water quality is excellent. Larva (glochidia) are released into the water and must attach as a parasite to a host fish species. There they develop into a juvenile mussel and eventually release the fish, falling onto a suitable bottom. Specific life histories attributes including hosts, duration of the parasitic stage, and water temperature interactions are unknown for these mussel species. Because of tremendous environmental variation in shell characters, freshwater mussels were taxonomically split into many small groups that have since been found to not represent full species. Older species names have been lumped together under new taxonomic treatements.

Habitat modifications, sedimentation, and water quality degradation are major threats to all these mussels. None will tolerate impoundments. Loss of native host fish, reduction of water flow, streambed erosion, water chemistry changes, pollution, dredging and increased turbidity are additional threats. In the past, freshwater mussels were used to punch out pearl buttons. Today, many are cut into "pearl seed" used as the central portion of pearls in Japanese production.

It is unlawful to "take" these federally protected species. "Take" is the act of, or attempt to, harm, harass, pursue, hunt, shoot, wound, kill, trap, capture, or collect a protected species. Prohibited acts include direct and indirect adverse changes in habitat. If you have any questions or concerns please contact the USDI Fish and Wildlife Service Field Office at Brunswick, GA (Ph. 912-265-9336).