A slide simply named “Oamaru Type Slide”. No makers name or details on the mountant. 38 examples, some intact and some fragments. Slide has issues with the mountant and adhesive to the coverslip. Olympus BHB microscope using 450nm LED light. The entire arrangement was imaged using a 10x Nikon Plan Apo NA 0.45 objective using brightfield lighting. 4 image stacks were prepared in Zerene (Pmax) and then pasted together in Photoshop. I selected 6 diatoms for imaging at higher resolution using 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 camera. Image stacked prepared in Zerene (Pmax).
Actinodiscus sp. Partial fragment. Bottom row, 7th from left. Possibly Actinodiscus corolla. 47 images stacked. Written about in Ross, R., & Sims, P. A. (2000). A revision of Actinodiscus Greville, Craspedoporus Greville and related genera (Eupodiscaceae). Diatom Research, 15(2), 285–347. https://doi.org/10.1080/0269249X.2000.9705500
Auliscus sigillum fragment. Underside view. Top row, 2nd from left. 36 images stacked.
Auliscus sp. (Auliscus elegans var. subpunctata ?). Top down view. 2nd row, 4th from left. 72 images stacked. I wondered about whether this was a few different ones (Auliscus dubius, Auliscus elegans var. subpunctata, Auliscus tenuistriatus). Diameter (75µm) could be any of these three. Based on Oamaru Diatoms website, I think this is most likely Auliscus elegans var. subpunctata as visually it is the closest.
Auliscus sp. 4th row, 3rd from left. 46 images stacked. Underside view, rim towards coverslip. Again I wondered about whether this was a few different ones (Auliscus dubius, Auliscus elegans var. subpunctata, Auliscus tenuistriatus). Less certain with this one than 3 although they are similar and this being an underside view doesn’t help.
Hyalodiscus radiatus var. striata Desikachary & Sreelatha, 1989. 4th row, 4th from left. 55 images stacked. Looks to be an underside view. Drops quite quickly towards the flat area in the middle. Sort of a truncated cone shape. Fairly sure on this one.
Cerataulus subangulatus. 5th row down, 8th from left. 56 images stacked. Viewed from the underside with the rim facing the coverslip. 4 of the 6 spines present (2 black dots towards the bottom right where two are missing). Spikes not visible though as below sharply defined structures but were visible in the original frames. This name is currently regarded as a synonym of Ceratangula subangulata (Grove & Sturt) P.A.Sims.
Overall some really interesting and unusual diatoms on here, but the mountant and coverslip adhesive issues made it a real challenge to image. Some of the other diatoms would be extremely hard to get good images of unfortunately.