Orastrum dispar Varol in Al-Rifaiy et al., 1990
honour of S. Kahveci, economist, Istanbul, Turkey
Holococcolith Kahvecia exhibits a prominent solid and narrow distal process, which either tapers or remains parallel-sided. The complete specimens naturally settle in a side-view position. From the side view, Kahvecia displays inclined extinction with length-slow (+) elongation.
In the plan view, the base of Kahvecia has a narrow rim surrounding a central area, which is divided into four blocks with or without pores by suture lines. Kahvecia displays inclined extinction with length-fast (-) elongation in the plan view.
Kahvecia differs from Isocrystallithus and Sarmania by having inclined extinction, whereas Isocrystallithus and Sarmania display parallel extinction.
From the side view, Kahvecia is distinguished from Owenia and Swapansahooia (all exhibit inclined extinction) by its narrow and solid distal process. In contrast, Swapansahooia displays a hollow distal process with sombrero-like termination. In contrast, the distal process of Owenia is raised from the two struts aligned with the short axis of the base and terminates with a plug.
The base of Kahvecia, as viewed in the plan, features a rim and four blocks. In comparison, the base of Owenia displays a rim with short projections along the short axis and two blocks aligned with the long axis. The base of Swapansahooia reveals a rim, four blocks and a central opening surrounded by struts.
Al-Rifaiy, I., Varol, O. & Lemone, D. 1990. Middle to late Albian biostratigraphy of the Cuchillo Formation from Sierra de Sapellò, Mexico. Newsletters on Stratigraphy. 21: 187-200.
Varol, O. 2025a. A practical guide to optical studies of calcareous nannofossils. Grzybowski Foundation Special Publication. 29: 1-222