Orastrum maghredaswampensis Lees, 2007
In honour of Dr Swapan K. Sahoo, Houston, Texas, USA
Holococcolith Swapansahooia exhibits a prominent
hallow distal process, which either tapers or remains parallel-
sided with sombrero-like termination. The complete specimens
naturally settle in a side-view position. From the side
view, Swapansahooia displays inclined extinction with lengthslow
(+) elongation.
In the plan view, the base of Swapansahooia has a narrow rim surrounding a central area with four blocks and a central hole
surrounded by struts. Swapansahooia displays inclined extinction
with length-fast (-) elongation in the plan view.
Swapansahooia differs from Isocrystallithus and Sarmania by having inclined extinction, whereas Isocrystallithus and Sarmania display parallel extinction. From the side view, Swapansahooia is distinguished from Owenia and Kahvecia (all exhibit inclined extinction) by its hollow distal process with sombrero-like termination. In contrast, Owenia and Kahvecia display a solid distal process.
The base of Swapansahooia, as viewed in the plan, features a rim, four blocks and a central hole surrounded by struts. 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 Kahvecia reveals a rim and four blocks.
Lees, J. A. 2007. New and rarely reported calcareous nannofossils from the Late Cretaceous of coastal Tanzania: outcrop samples and Tanzania Drilling Project Sites 5, 9 and 15. Journal of Nannoplankton Research 29(1): 39-65.
Varol, O. 2025a. A practical guide to optical studies of calcareous nannofossils. Grzybowski Foundation Special Publication. 29: 1-222