Davidhakania partingtonii Varol, 2025a
In honour of David Hakan Varol, Baildon, Yorkshire, U.K.
This elliptical discolith features a protolith outer wall, a very low sinistrally imbricated inner wall, and a central area spanned by a crossbar. Species of Davidhakania are distinguished by the orientation of the central crossbar and its arms.
Optical Properties: The outer wall remains in constant extinction, while the inner wall often exhibits greyish-white interference colours and length-fast (−) elongation in the plan view. In this orientation, the outer wall predominates over the inner wall. In the side view, both walls display interference colours the outer wall shows length-fast (−) elongation, while the inner wall exhibits length-slow (+) elongation.
Davidhakania differs from Neochiastozygus and Chiastozygus in that it has an outer wall of protolith. In Neochiastozygus, the height of the inner wall is roughly equal to that of the outer wall, while in Davidhakania, the inner wall is very low or absent, as it is in Chiastozygus.
Varol, O. 2025a. A practical guide to optical studies of calcareous nannofossils. Grzybowski Foundation Special Publication. 29: 1-222