Bomolithus aquilus Bown, 2010
Derived from the Greek Scoteini morfi, the dark form, refers to its interference colours under XPL.
Circular to sub-circular placoliths with a single layer , distal and appressed, distinctly narrower proximal shields.
Optical Properties: In the plan view, the distal shield and the tube cycle appear constantly extinct (the optic axis is vertical relative to the microscope stage, Plate 26, Figures 9, 11 in Varol, 2025). The thick distal shield displays parallel extinction (Plate 26, Figures 2, 6 in Varol, 2025) and a length-slow (+) elongation (Plate 26, Figures 1, 5 in Varol, 2025) in the side view.
The proximal shield displays a greyish-white interference colour, exhibiting inclined extinction lines and length-fast (-) elongation in the plan view. The proximal shield exhibits length-slow (+) elongation in the side view. The typical extinction angle is about 54° on the distal side in plan view.
Scoteinimorfi differs from Calcidiscus in that it has an extinct tube cycle (the optic axis is perpendicular relative to the microscope stage) and an appressed proximal shield.
Bown, P. R. 2010. Calcareous nannofossils from the Paleocene/Eocene Thermal Maximum interval of southern Tanzania (TDP Site 14). Journal of Nannoplankton Research 31(1): 11-38.
Varol, O. 2025. A practical guide to optical studies of calcareous nannofossils. Grzybowski Foundation Special Publication. 29: 1-222