A circular arrangement of diatoms from St Peter, Hungary. No makers name, but this is by Watson and Sons Ltd. Some movement of the diatoms and a few streaks in the mountant. Olympus BHB microscope using 450nm LED light. I selected one diatom for imaging further (what I am pretty sure is an example of Aulacodiscus reticulatus, just left of the middle of the arrangement in the 10 o’clock position). 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. 88 images stacked in Zerene (Pmax).
I say pretty sure this is A. reticulatus. It certainly has similarities to the St Laurent variety (for example here). However I wouldn’t say it was a 100% match. St Laurent is Lower Miocene, and St Peter Middle Miocene, so the ages are close but not a perfect match. I am however going to leave it as A. reticulatus for now pending other data.
An amazing arrangement and there plenty of other diatoms I want to image on this when time allows, so this page will hopefully be updated in the future.