Cyclicargolithus parvus Shamrock & Watkins, 2012
From the Greek ravdoto, striated, disko, disc, lithos, stone – refers to its striated shields.
Ravdotodiskolithos placoliths are characterised by two equal, distinctly striated distal and proximal shields of equal size. Prominent striations adorn the shields. Surrounding the very narrow central area is the tube cycle, which protrudes distally.
Optical Properties: The shields of Ravdotodiskolithos exhibit first-order greyish-white interference colours, while the tube cycle produces first-order white interference colours. The species displays inclined dextrogyre extinction lines with angles of approximately 81° on the shield and 67° on the tube cycle on the distal side and shows length-fast (-) elongation.
The unique characteristics of Ravdotodiskolithos provide critical diagnostic criteria for differentiating it from other genera within the Noelaerhabdaceae family. These features include a distally protruding tube cycle and equal-sized , non-concave-convex proximal and distal shields.
Varol, O. 2025a. A practical guide to optical studies of calcareous nannofossils. Grzybowski Foundation Special Publication. 29: 1-222