A new genus and two new species of dinoflagellate cysts from lower Eocene marine sediments of the Wilkes Land Margin, Antarctica

Integrated Ocean Drilling Program (IODP) Expedition 318 recovered lower Eocene sediments in Hole U1356A from the continental rise of the Wilkes Land Margin, Antarctica. These sediments yielded a new genus of organic-walled dinoflagellate cysts (Adeliesphaera gen. nov.). We tentatively place this new genus within the suborder Gonyaulacineae, family Areoligeraceae, based on the obligate apical archeopyle, the asymmetric antapical geometry and the left-side offset sulcal notch. We herein describe the type species of Adeliesphaera gen. nov., Adeliesphaera ohanlonii sp. nov., as well as a new species of Turbiosphaera, Turbiosphaera guersteinae sp. nov. The short stratigraphic range of both species (53.7-53.4 Ma and 53.1-52.9 Ma, respectively) qualifies them as potentially important regional Southern Ocean stratigraphic markers for high-resolution age control.