Aulacodiscus crux var. papulifera from Simbirsk. AS 162 6 (see below for this). Unknown maker. 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. 60 images stacked in Zerene (Pmax). Very thin slide, and debris over part of the diatom (mostly visible in the bottom left quadrant).
Aulacodiscus crux var. papulifera Brun in Schmidt et al., 1891. Original description: Schmidt, A. (1891). Atlas der Diatomaceen-kunde. Leipzig. Fues’s Verlag (R. Reisland), Series IV(Heft 41-42): pls. 161-168. Plate 162, Figure 6 (hence the AS 162 6 on the label).
I recently acquired about 30 more slides by this maker to add to the ones I already had, so if you want to see others by them, search for AAAAA in the Search option at the top of the page, and I’ll include this in each of the pages for them.