Pontosphaera callosa

Discolithina callosa Martini, 1969

In this Pontosphaera species, the walls are relatively high, and the proximal plate features pores arranged in five complete concentric cycles, with additional randomly arranged pores in the centre. The distal cover over the proximal plate is low, resulting in weaker interference colours in the central area compared to the wall under XPL in the plan view. The apparent angle between inclined extinction lines is 81°, corresponding to an obliquity angle of 9° on the distal side.

Martini, E. 1969. Nannoplankton aus dem Miozän von Gabon (Westafrika). Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen. 132: 283-300.

Varol, O. 1982. Calcareous nannofossils from the Antalya Basin, Turkey. Neues Jahrbuch für Geologie und Paläontologie, Monatshefte. 4: 244-256.