An arrangement of five Rattrayella sp. from Russia. Fossil marine material. The label says ‘oamaruensis ?, new species ?’. I’ll talk more about the name in in a minute. Mounted in Hyrax. Prepared by Flatters and Garnett Ltd. Olympus BHB microscope using 450nm LED light. As well as the arrangement I imaged the large one in the middle using the 40x Leitz Pl Apo NA 1.00 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, oblique lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 85 images stacked in Zerene (Pmax). 11 ocelli, dipping downwards towards the lower right.
Rattrayella oamaruensis (Grunow) De Toni, 1889: 691. Published in: De Toni, G.B. (1889). Algae novae. Notarisia 4: 671-701.
However I think these are Rattrayella simbirskiana (Grunow) Hanna 1934. Published in: Hanna, G.D. (1934). Additional notes on diatoms from the Cretaceous of California. Journal of Paleontology 8: 352-355. Page 335. This assignment is based on the description in; Sims, P.A. (2006). A revision of the genus Rattrayella De-Toni including a discussion on related genera. Diatom Research 21(1): 125-158. Homotypic synonyms; Eupodiscus simbirskianus Grunow 1887, Glyphodiscus simbirskianus (Grunow) Grunow 1888. However 11 ocelli would be high for this species.