Manumiella seymourensis new species, a stratigraphically significant dinoflagellate cyst from the Maastrichtian of Seymour Island, Antarctica

The peridiniacean dinoflagellate cyst Manumiella seymourensis new species d escribed herein characterizes Maastrichtian shallow marine sediments croppi ng out on Seymour Island, northeastern Antarctic Peninsula. It dominates pa lynological assemblages throughout the lower Maastrichtian (and possibly up permost Campanian) to lower upper Maastrichtian part of the Lopez de Bertod ano Formation. Despite its superficial similarity to some other southern mi d to high paleolatitude Campanian-Maastrichtian species, M. seymourensis re presents a discrete, biostratigraphically useful population of peridiniacea n cysts. Its morphology and size parameters remain consistent throughout al most all of its stratigraphic range, equated with relatively stable environ mental conditions throughout much of the Maastrichtian in the James Ross Ba sin. Morphological variations, equated with environmental change, are appar ent in specimens in the lowermost and uppermost parts of its range.