Genus classification of Triprojectacites Mtchedlishvili, 1961 emend. Stanley 1970

Triprojectacites Mtchedlishvili, 1961 emend. Stanley 1970 is an important pollen group of the Northern Hemisphere palynofloras during the Late Cretaceous. It is featured by three, or occasionally four or five, projections at the equatorial zone of the body with colpate apertures and endexinous thickenings. This pollen group is very useful in the stratigraphic division and correlation for its high diversity, short stratigraphic interval, and rapid evolution. However, the diversity and complex morphology make the pollen difficult to describe and classify, which brought discrepancies in the understanding and application of genus and species. In the present article, we make a re-evaluation of the previously proposed genera by using an improved, clearly defined morphological terminology based on standardised measurements. Finally, eight genera are screened out to set a new classification system from the 39 genera that have been proposed in relation with Triprojectacites. A diagnostic key is compiled for the convenience of differentiating them.