Medium to large (5-9 µm) circular-subcircular placoliths with a non-birefringent distal shield and narrow to closed central area surrounded by a narrow, bright tube cycle.
Medium-sized, broadly-elliptical placoliths with wide, low-birefringence shields and a very narrow central-area spanned by a small, disjunct, birefringent bar. The bar appears as two birefringent dots. A bright, narrow inner cycle may be visible.
Medium to large (6-9 µm) circular-subcircular placoliths with closed central area. Shield elements clearly visible and the proximal shield is typically significantly smaller then the distal.
Medium sized (5-6 µm) circular-subcircular placoliths with a non-birefringent distal shield, narrow bright tube cycle, and a narrow central area spanned by a small axial cross.
Small (3–4µm) broadly elliptical to circular; central-area closed; proximal shield smaller than distal and closed by an inner set of irregular elements
Medium-sized, circular-subcircular; central-area narrow & spanned by low-birefringence crossbars
Medium to large (~7-10µm), broadly elliptical placolith coccoliths with broad bicyclic rim (in XPL) and vacant, narrow central area. The rim width is greater than the central area width (rim width/central area width: 1.6-1.9).
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