Coscinodiscus sp. from Singelevo, Russia. Single example on the slide. Fossil marine material. Mounted in Styrax/Aroclor and dated September 1966. Prepared by ECP Bone. Olympus BHB microscope using 450nm LED light. 63x Leitz Pl Apo 1.4 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, oblique lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 35 images stacked in Zerene (Pmax).
Not really sure as to species, but Coscinodiscus denarius is about the closest I have found so far (based on appearance from the Oamaru Diatoms website). However this would be a very tentative ‘guess’ at this stage.