Aulacodiscus beeveriae (2 processes) from Lewis Island, California, USA. Not sure where Lewis Island actually is, as so far I’ve been unable to find any reference to it. If you know, let me know please… Single example on the slide. Prepared by William Allott Firth. 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. 42 images stacked in Zerene (Pmax). I stacked the processes separately and then blended them in in Zerene, as they were lost in the full stack. Looks a bit ‘odd’, but I think it’s better than losing them completely.
Aulacodiscus beeveriae S.I.Johnson 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 844, Plate VI [6], Figure 5 (as ‘Johnson MS’).
Also see: Stidolph, S. R.. “A Light and Electron Microscopical Study of the Diatom Aulacodiscus beeveriae Johnson in Pritchard, from New Zealand Coastal Marine Habitats” Botanica Marina, vol. 37, no. 1, 1994, pp. 75-82. https://doi.org/10.1515/botm.1994.37.1.75
I also have 3 and 4 process variants of A. beeveriae here.