Aulacodiscus reticulatus from St Laurent, France. Single example on the slide. Dated December, 1999. Prepared by Ralf Nötzel. Olympus BHB microscope using 450nm LED light. 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. 80 images stacked in Zerene (Pmax). I also imaged it with a 63x Leitz Pl Apo NA 1.40 oil immersion objective and oblique lighting (62 images stacked, Pmax). Although this does not show the whole diatom, the detail is amazing which is why I’ve included the whole frame with the 63x objective and a crop. The slide is very well made, and small metal spacers used for the coverslip, which are visible from the rear of the slide. All in all a beautifully made slide.
I got this as I wanted a named slide of A. reticulatus. I have one from a strew from St Laurent (here) and also one which I think is A. reticulatus (or something very closely related) from St Peter, Hungary (here). The St Peter one does show differences to this, but does have the ‘reticulated’ pattern. If more samples could be imaged of the St Peter one, now this one has been imaged, I suspect the St Peter one may well be considered a variant of A. reticulatus if not a separate species.