An arrangement of six diatoms labeled as Stictodiscus hardmanianus var. megapora from Oamaru, New Zealand. Mounted in Styrax. Prepared by Laurence Hardman. Olympus BHB microscope using 450nm LED light. As well as the arrangement, I imaged the middle one using a 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. 44 images stacked in Zerene (Pmax).
Stictodiscus hardmanianus var. megapora Grove & Sturt 1887. Published in: Grove, E. & Sturt, G. (1887). On a fossil marine Diatomaceous deposit from Oamaru, Otago, New Zealand. Part III. Journal of the Quekett Microscopical Club, Series 2 3: 63-78, pls 5, 6. Page 66, no figure.
This is quite a cool slide as it contains diatoms named after the slide maker. However it is hard to find good comparison images for S. hardmanianus var. megapora, so I am making an assumption that the one in the middle is this. The five around the outside show two Arachnoidiscus (probably A. oamaruensis), and three more Stictodiscus (looks to be S. hardmanianus, but may or may not be the megapora variants).