Cyclococcolithus leptoporus inversus Deflandre in Deflandre & Fert, 1954
Circular to subcircular placolith comprising a single-layered non-birefringent distal and proximal shield and a birefringent tube cycle. The assignment of Markalius to Calcidiscaceae is questionable.
Bramlette, M. N. & Martini, E. 1964. The great change in calcareous nannoplankton fossils between the Maastrichtian and Danian. Micropaleontology. 10(2): 291-322.
Deflandre, G. & Fert, C. 1954. Observations on current and fossil coccolithophorids in ordinary and electron microscopy. Annales de Paléontologie 40: 115-176.