An arrangement of Aulacodiscus sp. from Oamaru, New Zealand. 4 intact, and 1 partial. Prepared by Laurence Miles. Olympus BHB microscope using 450nm LED light. 20x Nikon Plan Apo NA 0.65 objective. Olympus Aplanat Achromat condenser, oblique lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 52 images stacked in Zerene (Pmax).
Label has these as A. subrimosus and A. cellulosus.
Aulacodiscus cellulosus. Aulacodiscus cellulosus E.Grove & G.Sturt 1887. Published in: Grove, E. & Sturt, G. (1887). On a fossil marine diatomaceous deposit from Oamaru, Otago, New Zealand. Part II. Journal of the Quekett Microscopical Club, Series 2, 3 (17). Journal of the Quekett Microscopical Club, Series 2 3(17): 7-12, 2 pls. Page 8, Plate II, Figures 8,9.
Aulacodiscus subrimosus. Aulacodiscus subrimosus Grunow 1888. Published in: Schmidt, A.[W.F.] (1888). Atlas der Diatomaceen-kunde Series III (Heft 31-32). pp. pls. 121-128. Leipzig: Fuess Verlag (R. Reisland). Plate 124, Figures 4,5.
As for what the ones on the slide are, here’s my thoughts.
Upper left (partial one) – Aulacodiscus comberii?
Lower right – Aulacodiscus cellulosus. Fairly sure on this one.
Other three – Aulacodiscus subrimosus. Looks like reasonable matches.