Coccolithus apomnemoneumus Hay and Mohler,1967
From the Greek chontri emfanisi, the coarse appearance, refers to its coarse appearance
The coccoliths are characterised by circular to elliptical placoliths featuring a larger concave-convex distal shield.
The proximal shield is lenticular, two-tiered (Plate 25, Figures 17-20 in Varol, 2025) and appressed with a rough appearance (Plate 25, Figures 1-8 in Varol, 2025). A narrow, smooth tube cycle blocks the central area.
Optical Properties: In the plan view, the distal and upper proximal shields exhibit constant extinction with optic axes perpendicular relative to the microscope stage. This contrasts with the inclined optic axes of the lower tier of the proximal shield, which show length-fast (-) elongation. The tube cycle exhibits parallel extinction and length-fast (-) elongation.
In the side view, the concave-convex distal and upper proximal shields display parallel extinctions at 0°, exhibiting length-slow (+) elongation. Meanwhile, the lower tier of the proximal shield is inclined, and the tube cycle exhibits parallel extinction lines, showing length-fast (-) elongation.
Chontriemfanisi differs from Coccolithus because it has a thicker distal shield and an appressed lenticular proximal shield. Coccolithus features thinner and well-separated shields. Additionally, the extinction lines on the tube cycle are parallel without bending in Chontriemfanisi, whereas they are diagonal and laevogyre distally in Coccolithus.
Hay, W. W., Mohler, H. P., 1967, Calcareous nannoplankton from Early Tertiary rocks at Point Labau, France and Paleocene-Early Eocene correlations. Journal of Paleontology 41(6), 1505-1541.
Schwarz, E. H. L. 1894. Coccoliths. Annals and Magazine of Natural History 14: 341-346.
Varol, O. 2025. A practical guide to optical studies of calcareous nannofossils. Grzybowski Foundation Special Publication. 29: 1-222