Sphenolithus cubaensis

Sphenolithus cubaensis Varol, in prep.

The apical spine of Sphenolithus cubaensis has an inclined extinction (extinction angle at 45°), whereas the apical spine of Sphenolithus runus has parallel extinction (extinction angle is 0°). The apical spines of Furcatolithus obtusus have oblique extinction (extinction angle is about 22°).

Sphenolithus strigosus has a strongly distally tapering apical spine (also showing incline extinction) with obtuse proximal and pointed distal ends. The distally gently tapering apical spine has flat proximal and distal ends in Sphenolithus cubaensis.

Bown, P. R., Dunkley Jones, T., 2006. New Paleogene calcareous nannofossil taxa from coastal Tanzania: Tanzania Drilling Project Sites 11 to 14. Journal of Nannoplankton Research 28(1), 17-34.

Bukry, D., 1971b. Cenozoic calcareous nannofossils from the Pacific Ocean. - San Diego Society of Natural History Transactions 16, 303-327.

Howe, R., 2021. Ultrastructure and taxonomy of the family Sphenolithaceae. Journal of Nannoplankton Research 39(1), 29-75.