Reassessment of Neovenericor Rossi de García, Levy y Franchi, 1980 (Bivalvia: Carditidae) using a geometric morphometric approach

PEREZ, DAMIÁN EDUARDO

Mar del Plata

Jornada; Reunión de Comunicaciones de la Asociación Paleontológica Argentina; 2015

Asociación Paleontológica Argentina

Previous works have discussed the systematic assignment of the Neogene planicostate venericardiids from Patagonia, represented only by one species: Neovenericor austroplata (Gardner and Bowles). On the one hand, some authors included this species within the genus Venericor Stewart (Eocene, North America and Europe) or in the genus Megacardita Sacco (Miocene, Europe). On the other hand, Rossi de García et al. erected the endemic genus Neovenericor for the Patagonian species. The three proposed genera show variable outlines and similar hinge teeth formula. Two geometric morphometric analysis were performed including the type species of each taxa: M. jouanneti (Basterot) (Middle Miocene, Mediterranean Basin), V. planicosta (Lamarck) (Middle Eocene, Paris Basin), and N. austroplata (Early Miocene, Chenque Formation, Chubut Province). In the first approach an Elliptic Fourier analysis was used to test the general variability of outlines (using 32 specimens). In the second one a landmark approach was performed to analyze the hinge configuration, followed by a Discriminant Function Analysis (DFA) (using 35 left valves and 39 right valves). The outline analysis allowed to separate Megacardita from the other two taxa based on its more enlarged and rectangular-shaped shells. The landmark analysis separated the three taxa based on both, left and right hinges. The DFA showed significative values for this separation. Neovenericor has higher hinge plate, broader and less inclined backwards teeth, and less sinuous ventral edge than Megacardita; and it has larger and more inclined backwards teeth than Venericor.