Aulacodiscus formosus from Mexillones (presumably Chile, Antofagasta Mejillones Bay; [described as “Mexillones Bay”], see https://diatoms.hsites.harvard.edu/smith). Single example on the slide. 4 processes. Yellowed mountant. Prepared by Laurence Miles. Olympus BHB microscope using 450nm LED light. 40x Leitz Pl Apo 1.00 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, oblique lighting. 2.5x Nikon CF PL photoeyepiece. 11mm removed from tube to the camera to increase the field of view. Monochrome converted Nikon d850 camera. 80 images stacked in Zerene (Pmax). Processes stacked separately as they became a bit lost against the background structure in the full stack.
Aulacodiscus formosus Arnott in Pritchard 1861. Published in: Pritchard, A. (1861). A history of infusoria, including the Desmidiaceae and Diatomaceae, British and foreign. Fourth edition enlarged and revised by J. T. Arlidge, M.B., B.A. Lond.; W. Archer, Esq.; J. Ralfs, M.R.C.S.L.; W. C. Williamson, Esq., F.R.S., and the author. pp. [1]-xii, [1]-968, 40 pls [I-XV]. London: Whittaker and Co.. Page 843.