Slide labelled as what looks to be Triceratium variabile from Rio [de]Janeiro. Single example on the slide. More on the name later. Prepared by Arthur Cottam. 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. 29 images stacked in Zerene (Pmax).
So, back to the name. On the label ‘Triceratium’ is very clear, but below that, very faint is what looks to be ‘varibile’. I searched for T. variabile, and there is reference to it in Schmidt’s Atlas, Plate 78, Figures 9-17, and yes some of these look similar to this one. I have also seen it spelt T. variable online. T. variabile has an alternate name: Biddulphia alternans var. variabilis (Brightwell) Mereschkowsky, 1900. This has a new name: Neobrightwellia alternans (Bailey) M.P.Ashworth & P.A.Sims. Published in: Sims, P.A., Ashworth, M.P., Theriot, E.C. & Manning, S.R. (2022 ‘2023’). Molecular and morphological analysis of Biddulphia sensu lato: a new diagnosis of Biddulphia, with a description of the new genera Biddulphiella and Neobrightwellia. Marine Micropaleontology 178(102186): 1-21, 21 figs. It therefore seems that the current name for this diatom should be Neobrightwellia alternans.