A New Species of Gouldia (Mollusca: Bivalvia) From the Pleistocene of Eastern North Carolina

Abstract

The small venerid bivalve Gouldia is represented by many look-alike species from both modern and fossil Cenozoic marine environments. In the western Atlantic- Caribbean region the genus consists of species that feature either an exterior surface sculpture of fine radial costae crossing the concentric growth bands on the anterior and posterior edges of valves, or a more uniformly reticulate pattern over the whole of valve exteriors. All of these forms are assigned to the subgenus Gouldia, with the best known and most widely distributed species being Gouldia (Gouldia) cerina (C. B. Adams, 1845), the type of the genus.

Owing to the discovery of a rare new species described herein, in the middle Pleistocene Flanner Beach Formation, eastern North Carolina (Fig. 1), a second supraspecific subdivision of Gouldia is here recognized. The members of this sub· genus have a surface ornamentation of coarse, flat costae that cross the concentric bands along the anterior and posterior ends of the valves, in contrast to the typical finely costate to reticulate surface design of most species of Gouldia.

The purpose of this note is to describe the new species from the Flanner Beach Formation, and to comment on its possible evolutionary and biostratigraphic significance. The general stratigraphy, geologic age and time-correlation, and paleoenvironmental contexts of the formation have been described by DuBar and Solliday (1963), Mixon and Pilkey (1976), McCartan et al. (1982), and Miller (this volume). All specimens have been deposited in the Academy of Natural Sciences of Philadelphia, Pennsylvania (ANSP).