An arrangement of Coscinodiscus elegans from Monterey, California, USA. Prepared by Arthur Cottam. Olympus BHB microscope using 450nm LED light. 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. Monochrome converted Nikon d850 camera. 41 images stacked in Zerene (Pmax).
Coscinodiscus elegans Greville 1866. Described in Greville, R.K. (1866). Descriptions of new and rare Diatoms. Series XIX. Transactions of the Microscopical Society, New Series, London, 14: 1-9, pls I, II. Page 3, Plate 1, Figure 6.
This name is currently regarded as a synonym of Actinocyclus rattrayi D.M.Williams 2024. Published in: Williams, D.M. (2024). Notes on the diatom collection of the Natural History Museum, London (BM) XI: the type specimens of Actinocyclus ingens Rattray and related specimens. Diatom Research 39(3): 149-158. Page 155.
Personally, I would have thought these would be closer to Cestodiscus species.