Pontosphaeraceae
Pontosphaera Lohmann, 1902
Optical Properties: The proximal plate and the outer wall remain in constant extinction, while the inner wall exhibits first-order interference colours with inclined extinction lines and length-fast (−) elongation in the plan view.
An elliptical cribrilith discolith consisting of three primary structural units: a perforated proximal plate, a dextrally imbricated outer wall, and a tangential inner wall with segments extending over the distal surface of the proximal plate in variable thickness.
The two main genera within Pontosphaeraceae, Pontosphaera and Transversapontis, are distinguished by the following structural differences:
- Transversapontis has struts at the junction of the proximal plate and the wall and a large opening on the proximal plate, often spanned by a bar.
- Pontosphaera lacks both struts and a large opening on the proximal plate.
Lemmermann, E. 1908. Flagellatae, Chlorophyceae, Coccosphaerales und Silicoflagellatae. In, Brandt, K. & Apstein, C. (eds) Nordisches Plankton. Botanischer Teil. Lipsius & Tischer, Kiel & Leipzig 1-40.
Lohmann, H. 1902. Die Coccolithophoridae, eine Monographie der Coccolithen bildenden Flagellaten, zugleich ein Beitrag zur Kenntnis des Mittelmeerauftriebs. Archiv für Protistenkunde. 1: 89-165.
