Abstract

Despite the abundance and diversity of Venericardia bivalves on the U.S. Coastal Plain during the Paleogene, the evolutionary relationships within the genus remain unresolved. The primary objectives of this study were to reconstruct a phylogeny of Venericardia species, identify major clades within the genus, and determine whether groupings within traditional venericard classifications constitute monophyletic taxa. Fifty-one conchological characters were applied to 18 venericard and two outgroup species. Parsimony analysis produced three equally parsimonious trees and robustness was assessed through Bremer support and bootstrap values. The resultant trees indicate that the smooth-ribbed planicostate venericards are monophyletic, whereas the sharp-ribbed alticostate venericards are paraphyletic. Additionally, the original planicostate subtaxon, Venericor, is monophyletic whereas the original alticostate subtaxa, Claibornicardia, Glyptoactis, and Rotundicardia, are nonmonophyletic.

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