A slide of diatoms from Szacal, Hungary. Labelled ‘Selected Actinoptychus boliviensis’ (more on the name in a minute) and mounted in Styrax. Prepared by Laurence Hardman. Olympus BHB microscope using 450nm LED light. As well as the arrangement I imaged three with a 63x Leitz Pl Apo 1.4 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, brightfield lighting for 2 (the Auliscus and the Actinoptychus which could be A. splendens) and oblique lighting for the other Actinoptychus. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. Image stacks prepared in Zerene (Pmax).
What are we looking at? The majority of the diatoms look to be one species of Actinoptychus. Given the label, I had assumed these were A. boliviensis, but looking at Schmidt’s Atlas, they look more like A. bifrons, A. stella or A. gründleri to me (all of which would be present at Szacal). There is one Actinoptychus which is different, ad this could be A. splendens (or a variant thereof). There’s also an Auliscus. Very (extremely) tentative ID for that, maybe Auliscus pulvinatus forma interis.
Actinoptychus boliviensis Janisch 1874. Published in: Schmidt, A.[W.F.] (1874). Atlas der Diatomaceenkunde. Series I, Heft 1. pp. pls 1-4. Aschersleben: [Verlag von Ernst Schlegel]. Plate 1, Figure 23. Actinoptychus stella A.W.F.Schmidt 1886. Published in: Schmidt, A.[W.F.] (1886). Atlas der Diatomaceen-kunde Series III: Heft 23. pp. pls 89-92. Aschersleben: Commissions-Verlag von Ludwig Siever’s Buchhandlung. Plate 90, Figure 1,2. Actinoptychus gruendleri A.W.F.Schmidt 1874. Published in: Schmidt, A.[W.F.] (1874). Atlas der Diatomaceenkunde. Series I, Heft 1. pp. pls 1-4. Aschersleben: [Verlag von Ernst Schlegel]. Plate 1, Figure 22 (as ‘gründleri‘). Also a variant on Plate 20, Figure 7. Actinoptychus bifrons A.W.F.Schmidt 1886. Published in: Schmidt, A.[W.F.] (1886). Atlas der Diatomaceen-kunde Series III: Heft 23. pp. pls 89-92. Aschersleben: Commissions-Verlag von Ludwig Siever’s Buchhandlung. Plate 90, Figure 6.
Also see Pantocsek’s 1886 book which covers some information on diatoms present at Szacal.