An arrangement of an Aulacodiscus sp. and 4 Arachnoidiscus sp. from Oamaru, New Zealand. Yellowed mountant, and 4 clear spacers under the coverslip. No makers name. Olympus BHB microscope using 450nm LED light. In addition to the arrangement, I imaged the Aulacodiscus sp. with 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. 77 images stacked in Zerene (Pmax).
So, what do I think this is? It has 8 processes, and looking around I think it is probably Aulacodiscus amoenus var. sparsipunctata. Although I am not 100% on it so will leave it with a question mark for now. Aulacodiscus amoenus var. sparsipunctata Desikachary & Sreelatha, 1989. Original description: Desikachary, T.V. & Sreelatha, P.M. (1989). Oamaru Diatoms. Bibliotheca Diatomologica, 19: pp. 3-330, pls 1-145. Pages 58-59, Plate 21, Figure 1-2.