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Cyclonaias infucata (Conrad, 1834)
Sculptured Pigtoe
Federal Protection: No US federal protection
State Protection: No Georgia state protection
Global Rank: G3?
State Rank: S3
Element Locations Tracked in Biotics: Yes
SWAP 2015 Species of Greatest Conservation Need (SGCN): No
SWAP 2025 Species of Greatest Conservation Need (SGCN): Yes
2025 SGCN Priority Tier: Moderate Conservation Concern
Element Occurrences (EOs) in Georgia: 64
Habitat Summary for element in Georgia: Large rivers to small creeks
Generally round shell to 68 mm. Anterior margin rounded and posterior slightly pointed. Periostracum brown to black. Outer surface of shell disk covered with small pustules from umbo to shell margin. Extent of pustules varies and tends to be more prominent on smaller individuals and may be completely absent on large animals. Nacre white or blue-white. Teeth large and heavy with a wide interdentum and shallow umbo pocket. Soft tissue usually tan but varies from white to light pink or orange (Williams et al., 2008; Williams et al., 2014).
C. infucata is fairly distinct from other species within its range but some small individuals may superficially resemble small Pleurobema pyriforme which tends to be more elongate and orange or golden brown. C. infucata has much heavier teeth than P. pyriforme, and shells of these two species can be easily distinguished.
C. infucata prefers sandy or gravely substrates in small streams and rivers with moderate to high flows. This species is usually found in deeper areas away from stream margins and is rarely found in low flow areas, oxbows, ponds, or impoundments.
The diets of unionids are poorly understood but are believed to consist of algae and/or bacteria. Some studies suggest that diets may change throughout the life of a unionid with juveniles collecting organic materials from the substrate through pedal feeding and then developing the ability to filter feed during adulthood (Vaughn and Hakenkamp, 2001).
Like all unionids, C. infucata has an obligate parasitic life cycle. Larval mussels, known as glochidia, develop in water tube present in the gills of the female mussel and are released when disturbed by an appropriate host fish. C. infucata is believed to be a short-term brooder and has been observed to be gravid in the spring and summer. Glochidia attach to the gills, fins, and skin of the host fish and encyst as an ectoparasite. Typical glochidia infestation appears to be minimally invasive to the host fish and is not fatal. Glochidia remain attached to the host for several weeks to several months before dropping off as juvenile mussels. These juveniles hopefully land in a new, suitable location and burrow into the sand where they feed on detritus using their foot and eventually grow into filter-feeding, adult mussels. Specific host species for C. infucata are unknown; however, other members of the genus Cyclonaias are known to utilize ictalurid (catfishes, bullheads, madtoms) and cyprinid (minnows, carps) host fishes.
Surveyors should consider sampling during periods when female individuals are spawning or brooding as this species may have higher detection rates during this period. However, since basic life history information for many of Georgia’s unionids is lacking, sampling during periods when closely related species are spawning or brooding may increase probability of detection. Investigators should conduct tactile searches of unconsolidated, but stabilized, habitats (i.e. sand around an embedded log) away from stream margins in moderate to high flow areas. Special attention should be paid to habitats where host species might be present.
C. infucata is known to occur in the Apalachicola and Ochlockonee River basins in GA and FL and the Apalachicola basin in AL.
Like most native freshwater mussels in Georgia, C. infucata is threatened by habitat destruction in the form of flow alteration, excessive water withdrawal, watershed land use changes, impoundments, and pollution. While the specific host fish species for C. infucata are not known, freshwater mussels are dependent on them to complete their life cycle and threats to host fish or barriers to host fish movement are also serious threats.
| Threat 1 | Threat 2 | Threat 3 | |
|---|---|---|---|
| General Threat | Agriculture & aquaculture | Natural system modifications | Natural system modifications |
| Specific Threat | None | Dams & water management/use | Dams & water management/use |
Conservation of C. infucata will primarily rely on habitat protection in the Flint and Ochlockonee rivers in the form of drainage area, riparian, and water resource management. Flow and connectivity restoration through the removal of low head dams may allow this species to recolonize portions of its previous home range in the Chattahoochee River. Further research into the specific life history, host fish, and habitat requirements of this species are still needed to guide management efforts.
Vaughn C.C. and C.C. Hakenkamp. 2001. The functional role of burrowing bivalves in freshwater ecosystems. Freshwater Biology 46:1431-1446.
Williams, J.D., A.E. Bogan, and J.T. Garner. 2008. Freshwater mussels of Alabama and the Mobile Basin in Georgia, Mississippi, and Tennessee. The University of Alabama Press, Tuscaloosa.
Williams, J.D., R.S. Butler, G.L. Warren, and N.A. Johnson. 2014. Freshwater Mussels of Florida. University of Alabama Press, Tuscaloosa, Alabama.
Matthew Rowe
1/9/2020
