A NEW SPECIES OF PROTOSCUTELLA (ECHINOIDEA, PROTOSCUTELLIDAE) FROM THE MIDDLE EOCENE SANTEE LIMESTONE OF SOUTH CAROLINA, WITH A REVIEW OF THE GENUS PROTOSCUTELLA

Recent collecting in the middle Eocene Santee Limestone in Berkeley County, South Carolina has provided a new species of the echinoid genus Protoscutella for study. Specimens of Protoscutella n. sp., were collected below the occurrence of Protoscutella mississippiensis mississippiensis (Twitchell) which occurs in the same quarry. The authors have demonstrated that these specimens represent a distinct species, with a test width that is significantly wider than long (test width equals up to 158% test length) throughout growth, with the point of greatest width positioned further posteriorly than any other Protoscutella, giving the test a distinctly triangular shape in larger specimens. These features readily distinguish it from the subpentagonal to ovate tests of its cogeners. Additionally, the periproct of Protoscutella n. sp., is consistently supramarginal, throughout growth, and is positioned higher on the aboral surface than any other species of Protoscutella.

The addition of Protoscutella n. sp., will increase the number of described species of Protoscutella to six species and one subspecies, including: P. conradi (Cotteau), P. mississippiensis mississippiensis (Twitchell), P. pentagonium (Cooke), P. plana (Conrad), P. toumeyi (Twitchell), and the subspecies P. mississippiensis rosehillensis (Kier). As a result of this study, the authors do not recognize Protoscutella toumeyi (Twitchell) as a distinct species, and consider it to be a subjective junior synonym of Protoscutella conradi (Cotteau). We therefore, recognize five species of Protoscutella, all of which are reviewed as part of this project.

The addition of Protoscutella n. sp., as well as a new species of Salenia from the same horizon, (the first occurrence of the genus Salenia in the Eocene of North America) increases the number of echinoid species recorded from the Santee Limestone to seventeen.

Protoscutellid sand dollars are important index fossils in the middle and upper Eocene of the Atlantic and Gulf Coastal Plains. So the succession of the Protoscutellidae in the Carolinas is clarified: Protoscutella n. sp., to P. mississippiensis (Twitchell) to P. conradi (Cotteau), to P. plana (Conrad), to Periarchus lyelli (Conrad).