Three examples of Stauroneis inflata (more on the name in a minute) and a sponge spicule, from Ongaroto Valley, New Zealand. Prepared by JA Long. Olympus BHB microscope using 450nm LED light. As well as the arrangement the one at the left was imaged 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. 28 images stacked in Zerene (Pmax). All the Stauroneis are viewed from the underside with their rims to the coverslip.
Ok, names.
Stauroneis inflata Kützing 1844. Published in: Kützing, F.T. (1844). Die Kieselschaligen Bacillarien oder Diatomeen. pp. [i-vii], [1]-152, pls 1-30. Nordhausen: zu finden bei W. Köhne. Page 105, Plate 30, Figure 22. This name is currently regarded as a synonym of Achnanthes inflata (Kützing) Grunow. Source of synonymy; Grunow, A. (1868 ‘1867’). Algae. In: Reise der österreichischen Fregatte Novara um die Erde in den Jahren 1857, 1858, 1859 unter den Befehlen des Commodore B. von Wüllerstorf-Urbair. Botanischer Theil. Erster Band. Sporenpflanzen. (Fenzl, E. et al. Eds), pp. 1-104. Wien [Vienna]: Aus der Kaiserlich Königlichen Hof- und Staatsdruckeri in Commission bei Karl Gerold’s Sohn.
Stauroneis inflata Heiden, nom. illeg. 1903. Published in: Schmidt, A.[W.F.] (1903). Atlas der Diatomaceen-kunde Series VI: Heft [61]. pp. pls 241-244. Bearbeitet von Dr. M. Schmidt. Leipzig: O.R. Reisland. Plate 241, Figures 2, 8, 11. This name is currently regarded as a synonym of Stauroneis heidenii Forti.
From Schmidt’s Atlas these look like Stauroneis inflata Heiden / Stauroneis heidenii Forti.
However looks like Stauroneis acuta Wm. Smith from Barber. HG. 1961: The fossil freshwater diatoms of the Ongaroto Valley deposit, North Island, New Zealand. Journal of the Queckett Microscopical Club. Series 4. 5: 387-391, Figure 26. Also Schmidt’s Atlas Plate 241, Figures 2,4,11. This name seems to be a better match to current naming conventions.