There quite a lot going on on this slide, and the label has been crossed out and modified at some point. There are five Actinoptychus and two Lithisted dermal spicule of Discodermia. Sample from Oamaru, New Zealand. ‘Vulgaris‘ has been crossed out and replaced with ‘maculatus‘, then with four measurements – 50, 110, 110, 165µm, so presumably it was thought that there were four examples of A. maculatus. ‘Unknown’ and ‘Diatom?’ have been crossed out and replaced with ‘racemosus‘ and ‘2 spicules‘. I am taking this to mean that the unknown diatom has been named as A. racemosus, and the two other things aren’t diatoms but are spicules (the Lithisted dermal spicule of Discodermia).
I also think the small A. maculatus is not that but is probably an example of Actinoptychus fuscus.
Olympus BHB microscope using 450nm LED light. As well as the entire arrangement I imaged the three from the left of the group 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. 11mm of the tube to the camera removed to increase the field of view. Monochrome converted Nikon d850 camera. 66 images stacked in Zerene (Pmax). I think these are Actinoptychus maculatus (the large one on the left), Actinoptychus fuscus (the small one at the upper right), and Actinoptychus racemosus (the small one at the lower right). I am fairly sure with the ID’s for A. maculatus and A. racemosus, but less sure about the A. fuscus.
Actinoptychus maculatus A.W.F.Schmidt 1888. Published in: Schmidt, A.[W.F.] (1888). Atlas der Diatomaceen-kunde. Series III: Heft 33-34 [“Heft 29-30”]. pp. pls 129-136. Aschersleben: Verlag von Ludwig Siever. Plate 132, Figures 18-20.
Actinoptychus fuscus Grove & Sturt 1888. Published in: Schmidt, A.[W.F.] (1888). Atlas der Diatomaceen-kunde. Series III: Heft 33-34 [“Heft 29-30”]. pp. pls 129-136. Aschersleben: Verlag von Ludwig Siever. Plate 132, Figure 21.
Actinoptychus racemosus A.Schmidt 1890. Published in: Schmidt, A.[W.F.] (1890). Atlas der Diatomaceen-kunde Series IV: Heft [39/40]. pp. pls 153-160. Leipzig: Fues’s Verlag (R. Reisland). Plate 153, Figure 2.
Interestingly, the 153.2 on the label, I had originally assumed was a diameter like the other numbers, but it actually refers to the plate and figure in Schmidt’s Atlas for A. racemosus (Plate 153, Figure 2).