An arrangement of 4 diatoms from Cambridge, Barbados. Unknown slide maker. Olympus BHB microscope using 450nm LED light. I selected one to image at higher resolution. 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. 46 images stacked in Zerene (Pmax). The 20x image is softer than I expected, and I think that is due to quite a pronounced film over the surface of the slide. In future, they will all be cleaned properly before imaging.
Ok, the diatom names. The slide says 3 Coscinodiscus, Aulacodiscus barbadensis. Here’s my thoughts on these, from left to right in the 20x objective image.
1. I don’t think this is Aulacodiscus barbadensis. Possibilities. Aulacodiscus crux (Schmidt’s Atlas Plate 33, Figure 1, good visual match but not reported at Cambridge). Aulacodiscus kilkellyanus (pretty good match visually – Desikachary and Sreelatha’s Oamaru book – and reported at Cambridge). Overall not sure.
2. Maybe Azpeitia nodulifer. Original name: Coscinodiscus nodulifer A.W.F.Schmidt, 1878.
3. Maybe Thalassiosira leptopus. Original name: Coscinodiscus leptopus Grunow, 1883. Also called Coscinodiscus lineatus var. leptopus.
4. I think this could be Coscinodiscus crassus (Schmidt’s Atlas Plate 61, Fig 19, from Cambridge, Barbados). However lacking high resolution comparison images, I’ll leave this with a question mark for now.
I recently acquired about 60 slides by this maker, so if you want to see others by them, search for AAAAA in the Search option at the top of the page, and I’ll include this in each of the pages for them.