Olladiscoaster cruzii

Olladiscoaster cruzii Varol & Bowman, 2024

Circular species of Olladiscoaster have segments without arms. On the distal side, the distinct sutural ridges are created by the deep cavities. The sutural ridges are raised towards the centre and capped by boomerang-shaped distal covers. The distinct proximal ridges with a petaloid knob decorate the bulged proximal side. At the side view, Olladiscoaster cruzii is characterised by a very low proximal knob and very high, gradually raised sutural ridges.

In honour of Dr Jarret Cruz, nannofossil specialist, Bugware Inc., Tallahassee, Florida, USA.

Maximum diameter: 5.12 µm, Maximum height: 4.24 µm; Diameter of the proximal knob: 1.86 µm, Height of the proximal knob: 0.55 µm (measurements from cross-polarised micrograph).

The circular shape Olladicoaster cruzii is differentiated from other armless Olladiscoaster with a boomerang shape distal cover, such as Olladiscoaster catinatus, Olladiscoaster asterilithos and Olladiscoaster asterilithos, by having a petaloid proximal knob. Olladiscoaster catinatus and Olladiscoaster exagonikoasteri lack proximal knobs, whereas Olladiscoaster asterilithos has a radiating proximal knob. Moreover, Olladiscoaster exagonikoasteri has a hexagonal shape outline.

Varol, O. & Bowman, A. R. 2024. The New Middle Miocene Genus Olladiscoaster, and Related and Associated Discoasters. Grzybowski Foundation Special Publication, 28: 1-103 pp.