Date of Award

January 2022

Degree Type

Open Access Thesis

Document Type

Master Thesis

Degree Name

Master of Science (MS)


Biological Sciences

First Advisor

David M. Hayes

Department Affiliation

Biological Sciences

Second Advisor

Amy Braccia

Department Affiliation

Biological Sciences

Third Advisor

Stephen R. Richter

Department Affiliation

Biological Sciences


North America is home to nearly 300 species of native freshwater mussels. Many species within this group are in need of conservation efforts and for these efforts to be effective, species delimitations must be as accurate as possible. Intraspecific variation and interspecific convergence are sources of confusion within morphology-based taxonomy, particularly within the Pleurobemini. Molecular phylogenetic work has revealed multiple problems within currently accepted Pleurobemini classifications. Specifically, Fusconaia has been shown to harbor cryptic diversity within drainages of the Ozarks. Further, Pleurobema rubrum and P. sintoxia have been shown to be possible conspecifics despite have differing shell morphologies. This study sought to use the COI mitochondrial gene to investigate the taxonomic identity of Pleurobemini specimens from within the Ozarks and to use geometric morphometrics to investigate inter- and intraspecific morphological variation. Genetic data revealed that an unnamed Fusconaia lineage, previously identified in other studies, occupies all major river systems draining the Ozark Highlands except the White River system. F. flava and F. ozarkensis, however, were only found in the White River system. P. rubrum and P. sintoxia were not differentiated at the COI gene. This was consistent in all drainages sampled. Geometric morphometric data revealed varying degrees of morphological overlap between all taxa in regards to both shell outline and shell inflation shapes, although discriminant analysis reclassification was largely successful in identifying data points.