New organic-walled dinoflagellate cyst species from the Upper Cretaceous–Lower Palaeocene Chalk Group in the Meer and Turnhout boreholes, Campine Basin, northern Belgium

The Campanian to Danian Chalk Group from the Meer and Turnhout boreholes in the Campine Basin, northern Belgium, contains four new species and a subspecies of organic-walled dinoflagellate cyst previously left in open nomenclature. These species were recorded within rich, diverse and well-preserved assemblages and are formally described here. A re-assessment of their stratigraphic ranges is presented. Apteodinium crassus sp. nov. is characterized by a very thick and finely spongeous wall, with or without a cingulum. Cribroperidinium wilsonii subsp. trabeculosum subsp. nov. is distinguished by its slender processes that are distally uniformly connected by thin trabeculae. Elytrocysta elongata sp. nov. differs from other Elytrocysta species by its small size and the elongate cylindrical shape. Spinidinium delicatum sp. nov. is a small Spinidinium species and has very delicate sutural crests that are very finely serrate to finely denticulate. Spumadinium irregulare sp. nov. is an intermediate to large holocavate dinoflagellate cyst with the endophragm and periphragm irregularly connected by thin columellae or pillars of different length.

► We describe five new dinocysts from Campanian–Danian Chalks in Belgium.
► We name four species and a subspecies Cribroperidinium wilsonii subsp. trabeculosum.
► Apteodinium crassus Elytrocysta elongata Spinidinium delicatum Spumadinium irregulare.
► We present stratigraphic ranges of these dinocysts in the Meer and Turnhout boreholes.
► The new species are important stratigraphical markers for Campanian–Danian strata.