Late Miocene (Tortonian) gonyaulacacean dinoflagellate cysts from the Vienna Basin, Austria

During the Late Miocene (Tortonian or Pannonian regional stage), at around 11.6 Ma, a glacioeustatically-driven sea-level fall caused the final closure of the Paratethys Ocean and Lake Pannon was formed in central Europe. The lake was initially brackish, but slowly freshened and became slightly alkaline. These unusual changes in water chemistry produced the radiation of a characteristic assemblage of gonyaulacacean dinoflagellate cysts. This study examined 94 samples from the Pannonian of Hennersdorf Clay Pit, south of Vienna, Austria. From this material, Achomosphaera brevis sp. nov., Seriliodinium? imperfecta sp. nov. and Spiniferites hennersdorfensis sp. nov. were apparently endemic to the Central Paratethys during the Late Miocene. Spiniferites bentorii (Rossignol 1964) Wall and Dale, 1970 subsp. oblongus Sütőné-Szentai 1986 and Spiniferites bentorii (Rossignol, 1964) Wall and Dale 1970 subsp. pannonicus Sütőné-Szentai 1986 are elevated to species status. The genus Spiniferites exhibited significant morphological variability especially in terms of general shape, apical boss development and process morphology. Supplementary descriptions and discussions of some other gonyaulacacean taxa which are present are provided.