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Hamiota altilisFinelined Pocketbook
Federal Protection: Listed Threatened
State Protection: Threatened
Global Rank: G2G3
State Rank: S2
SWAP High Priority Species (SGCN): Yes
Element Occurrences (EOs) in Georgia: 32
Habitat Summary for element in Georgia: Small streams to large rivers; sand, gravel, and cobble substrates; usually not in swift current
Shell profile ovate with a maximum length of approximately 117 mm (4⅝ inches). The umbo is positioned anteriorly of the middle of the valves and is elevated slightly above the hingeline. Shell is broadly rounded anteriorly and sharply rounded posteriorly with males exhibiting a more pointed appearance. Ventral margin is broadly rounded. Posterior ridge low or broadly rounded. The periostracum dull to glossy and yellow to dark brown with fine dark rays radiating from the umbo to the margin of the shell. Left valve has two compressed, triangular pseudocardinal teeth and two long, but straight lateral teeth. Right valve with one stout, triangular pseudocardinal tooth. Umbo cavity shallow. Nacre color typically white or salmon.
Alabama Rainbow (Villosa nebulosa). The Finelined Pocketbook is distinguishable from the Alabama Rainbow in that the posterior margin of the Finelined Pocketbook tends to be more broadly rounded than that of the Alabama Rainbow. The pseudocardinal teeth in the Finelined Pocketbook also tend to be heavier than those in the Alabama Rainbow.
Typically occupies small streams to large rivers in sandy to muddy sand substrates or gravel shoals with slight to moderate current.
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 though pedal feeding and then developing the ability to filter feed during adulthood (Vaughn and Hakenkamp 2001).
Females are known to brood glochidia from late summer through late spring and release superconglutinates during this time. The superconglutinate is comprised of a long gelatinous string with several glochidial packages attached and floats on the water current to resemble a small fish. The purpose of the superconglutinate is to attract predatory host fishes. Glochidia of this species successfully transformed on Largemouth Bass (Micropterus salmoides), Spotted Bass (M. punctatus), Coosa Bass (M. coosae), and Green Sunfish (Lepomis cyanellus) (Haag et al. 1995).
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.
This species is endemic to the eastern Mobile Basin of Alabama, Georgia, and Tennessee and was historically reported from the Tombigbee, Black Warrior, Cahaba, Alabama, Tallapoosa, and Coosa River drainages. Currently, the Finelined Pocketbook appears to be restricted to the Cahaba, Coosa, and Tallapoosa River drainages. In Georgia, this species is currently extant in the Tallapoosa River, Conasauga River, Ellijay River and several of their tributaries. A lone individual was collected from Euharlee Creek in the Etowah River Basin in Georgia during a 2002 survey. This population was re-surveyed in 2014 and several additional individuals were collected. A previously unknown and substantial population of the Finelined Pocketbook was discovered in the Ellijay River and a tributary during 2013 surveys. An additional population was discovered in the Shoal Creek watershed in Cherokee County during June 2017.
Currently, the Mobile Basin of Georgia is experiencing substantial development and timber removal along the banks. Excess sedimentation due to inadequate riparian buffer zones, development, and agriculture covers suitable habitat and could potentially bury mussels. Poor agricultural practices may also cause eutrophication and degrade water quality. Proposed reservoirs may fragment or inundate extant populations in the Tallapoosa River Basin.
The Finelined Pocketbook does not occur on any state properties in Georgia. Unlike terrestrial species, the occurrence of an aquatic species on state or federal lands may not eliminate habitat degradation due to the influences of upstream and downstream disturbances.
Minimizing sedimentation in the Conasauga River and its tributaries is a key component to conserving the Finelined Pocketbook. Restoration of riparian buffers will stabilize banks providing clean gravel and sand substrates for the species. If habitat degradation can be minimized, reintroduction/augmentation of the Finelined Pocketbook populations should be explored in order to re-establish viable populations of the species. However, prior to initiating any reintroduction/augmentation projects for the Finelined Pocketbook, the effective population size of this species should be examined to ensure that these actions would not negatively affect the genetic integrity of the population. Surveys for the Finelined Pocketbook in the Tallapoosa River Basin in Georgia were recommended in Georgia's 2015 State Wildlife Action Plan.
Haag, W.R., R.S. Butler, and P.D. Hartfield. 1995. An extraordinary reproductive strategy in freshwater bivalves: prey mimicry to facilitate larval dispersal. Freshwater Biology 34: 471-476.
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.