Sphenolithus strigosus Bown & Dunkley Jones, 2006
The apical spine of Sphenolithus strigosus 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°).
The distally gently tapering apical spine (also shoving an inclined extinction) has flat proximal and distal ends in Sphenolithus cubaensis. Sphenolithus strigosus has a strongly distally tapering apical spine with obtuse proximal and pointed distal ends.
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.
Bown & Dunkley Jones, 2006
TDP Site 13, Pande, Tanzania