A strew slide from Sonsbeek, Holland, below waterfall. Prepared by Brian Darnton. Various diatoms (including Actinoptychus, Cymbella, Gomphonema and Odontella) but mainly Epithemia (maybe E. turgida). Olympus BHB microscope using 450nm LED light. Main image of the Actinoptychus sp. with a 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. 30 images stacked in Zerene (Pmax).
I picked on the Actinoptychus on the slide to do a higher magnification image. It looks to be very much like Actinoptychus splendens, however as far as I am aware that is not a freshwater species (which this environment should be). I shall leave it with a question mark for now.