Sphaeripilosa wernerpilleri, a new peridinioid dinoflagellate genus and species from the late Miocene of Lake Pannon, Austria

Sediments of the late Miocene of Lake Pannon have been studied extensively for preserved fauna and flora. Processed samples have yielded many well-preserved species of dinoflagellate cysts. Ultra-high-resolution core samples (sampled at 0.5 cm intervals) from Hennersdorf, in the Vienna Basin, and nearby outcrop samples contain, in some parts, abundant specimens of a new genus and species of dinoflagellate cyst, Sphaeripilosa wernerpilleri. The new species is a thin-walled, acavate cyst, spherical to subspherical with a distinctive dense surface ornamentation consisting of short, hair-like, solid, evexate processes. The new genus is evidently peridinioid. Interpretation of the tabulation is based almost entirely on the shape of the archeopyle, which we studied in detail. We considered three hypotheses for archeopyle interpretation and concluded, mainly by elimination, that it is mesoepicystal (3A3I), making it ovoidinioid. Sphaeripilosa wernerpilleri appears to be an indicator of low salinity and high nutrient environments as well as a stratigraphic indicator for the late Miocene (Tortonian), Pannonian Regional Stage. It may also represent a transition in peridinioid evolution to a tabulation pattern that is common in the Miocene marine calcareous calciodinelloids, in this case as an organic-walled cyst living in fresh to brackish water.