Aulacodiscus sturtii from Japan. 4 processes, the one at 9 o’clock is damaged/missing. Single example on the slide. Prepared by Frederick Marshall. 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. 54 images stacked in Zerene (Pmax). In the initial full stack the processes were lost as they are quite faint. I did a partial stack to emphasize them, although I am not really happy with how it turned out (although they can at least be seen now).
Aulacodiscus sturtii Kitton, 1884. Published in: Kitton, F. (1884). Description of some new Diatomaceae found in the stomachs of Japanese oysters. Journal of the Quekett Microscopical Club, Series 2 2: 16–23, 1 plate [pl. 4]. Page 17, Plate IV, Figure 1.