A genetic approach to resolving taxonomic ambiguity among Pleurobema (Bivalvia: Unionidae) of the eastern Gulf Coast


Freshwater mussels in the genus Pleurobema (Bivalvia: Unionidae) from the eastern Gulf drainages of Florida, Georgia, and Alabama are variable conchologically, and several taxonomic names have been applied to shell phenotypes. Clarification of the species status of these mussels is important because they are recognized as imperiled throughout their range, mainly due to habitat destruction. Allozyme electrophoresis and restriction fragment length polymorphisms (RFLPs) of the nuclear ribosomal array showed little genetic differentiation among samples representing the phenotypes designated P. pyriforme and P. bulbosum. Partial DNA sequences of the mitochondrial cytochrome c oxidase subunit 1 distinguished P. reclusum from P. pyriforme and P. bulbosum. Genetic differentiation was observed between other Pleurobema species, specifically P. strodeanum, P. clava, and P. sintoxia. Genetic evidence indicates that the eastern Gulf Coast Pleurobema (P. pyriforme and P. bulbosum) are a single species, P. pyriforme, with variable shell characteristics. Pleurobema reclusum is different genetically and may represent a distinct valid species. Pleurobema pyriforme is a federally endangered species. Although we hesitate to call P. reclusum a distinct species because we were able to sequence DNA from only one individual, it is distinct genetically from P. pyriforme of the Apalachicola-Chattahoochee-Flint rivers basin and should merit conservation status.



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Allozymes, Conservation, DNA sequencing, Endangered species, Pleurobema, RFLP analysis, Unionidae

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