Dictyococcites danicus Black, 1967
Elliptical to circular reiculofenestrid having unicycle distal and proximal shields and a tube cycle. The central area is covered by a plug distally and a central mesh proximally. The entire coccolith is birefringent under polarised light.
The plug may or may not cover the entire central area distally. Under the light microscope, the tube cycle and the plug cannot be distinguished from each other.
Elliptical Groups
Dictyococcites stavensis Group
Plug completely closed the central area
Dictyococcites pseudolockeri Group
Plug partly closed the central area
Circular Group
Dictyococcites erbae Group
Plug completely closed the central area
Dictyococcites differs from Reticulofenestra Hay, Mohler & Wade (1966), Cribrocentrum Perch-Nielsen (1971) and Cyclicargolithus Bukry (1971) by having a distal plug. It is further differentiated from Reticulofenestra and Cyclicargolithus by having a birefringent permanent central mesh. The species of Dicyococcites are primarily identified based on their shape and size. The ratio of pelaga to the central area and complete or incomplete plug are also used for speciations.
Bukry, D., (1971): Cenozoic calcareous nannofossils from the Pacific Ocean. - San Diego Society of Natural History Transactions. 16: 303-327.
Hay, W. W., Mohler, H. P. & Wade, M. E., (1966): Calcareous nannofossils from Nal'chik (northwest Caucasus). - Eclogae Geologicae Helvetiae. 59: 379-399.
Levin, H. L. & Joerger, A. P., (1967): Calcareous nannoplankton from the Tertiary of Alabama. - Micropaleontology. 13(2): 163-182.
Perch-Nielsen, K., (1971): Elektronenmikroskopische untersuchungen an Coccolithen und verwandten Formen aus dem Eozan von Danemark. - Biologiske Skrifter, Kongelige Danske Videnskabernes Selskab. 18(3): 1-76.