Sullivania a new genus of Palaeogene coccoliths

It is shown that the genus Chiasmolithus as currently understood comprises two discrete lineages. It is proposed that these should be formally recognised as separate genera. A new genus, Sullivania, is described and ten new combinations: S. californica, S. consueta, S. danica, S. edwardsii, S. gigas, S. inconspicua, S. minima, S. nitida, S. titus and Cruciplacolithus oulchyensis are introduced. The speculative evolution in the genera Cruciplacolithus, Sullivania and Chiasmolithus is discussed and illustrated.