Slide labelled as Triceratium exornatum from Park’s Plantation, Barbados. However I am pretty sure this name is wrong – it doesn’t look like T. exornatum, and I’ll share more thoughts on this later. Sty.aro (Styrax aroclor) mountant, and dated February 1966. Prepared by ECP Bone. Olympus BHB microscope using 450nm LED light. 63x Leitz Pl Apo NA 1.4 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, slightly oblique lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 48 images stacked in Zerene (Pmax).
Right, the name. This doesn’t look like Triceratium exornatum (for example see Schmidt’s Atlas, Plate 112, Figures 1 and 2). It looks more like Triceratium plicatum to me but it doesn’t have the strongly concave sides of the one in Schmidt’s Atlas (Plate 94, Figure 8) or the others I have assigned to this name on this site. But other than this is very similar, morphologically, to the ones I have assigned to that name previously. Could this be a ‘non-concave’ form? I’m not sure, so am leaving this with a question mark for now.
Triceratium plicatum Grunow in Van Heurck 1883. (as ‘Triceratium (Biddulphia) plicata‘ ). Published in: Van Heurck, H. (1882). Synopsis des Diatomées de Belgique. Atlas. pp. pls LXXVIII-CXXXII [78-132 and supplementary pls 22 bis, 82bis, 83bis, 83ter, 95bis], tables genres. Anvers: Ducaju et Cie. Plate 113, Figure 10, no description.
EDIT 14/11/25. I recently got another slide labelled T. exornatum which looks similar to this one, but with more concave sides (see here). Neither of these looks like the ones in Schmidt’s Atlas. I have however dug a bit deeper into possible names. All very mysterious. Any ideas, let me know.