New dinoflagellate cyst species of the Microdinium and Phanerodinium Complexes (Evitt) from the Upper Cretaceous–Lower Paleogene Chalk Group in the Meer borehole, northern Belgium

A high-resolution palynological study of the Campanian to Danian Chalk Group from the Meer borehole in northern Belgium has revealed the presence of four new smaller organic-walled dinoflagellate cyst species previously left in open nomenclature, within rich, diverse and well-preserved assemblages. A formal description of the new species, an emendation of Phanerodinium fourmarieri Lejeune-Carpentier based on a comparison of well preserved specimens with the type material, and as a result a re-assessment of the stratigraphic occurrences of each of these species are provided. Druggidium discretum sp. nov. is characterized by a finely spongeous wall surface and a discreet indication of tabulation, while Druggidium meerensis sp. nov. is suturocavate with a granulate, vermiculate to rarely pseudoreticulate ornamentation. Gillinia denticulata sp. nov. is distinguishable by its high and denticulate crests. Phanerodinium belgicum sp. nov. has a microgranulate to vermiculate surface wall and membranous crests. We retain Phanerodinium fourmarieri in the genus Phanerodinium, and reject the transfer of the species to the genus Druggidium by Lejeune-Carpentier and Sarjeant, as we demonstrate that the ventral surface of the species is untabulated and that the anterior intercalary plates are lacking. Both features are characteristic of every Phanerodinium species.

► New dinoflagellate cysts from Campanian–Danian Chalks in the Meer borehole (Belgium).
► Druggidium discretum, D. meerensis, Gillinia indentata and Phanerodinium belgicum.
► We emend Phanerodinum fourmarieri and reject its transfer to the genus Druggidium.
► The new species are important stratigraphical markers for Campanian–Danian strata.