A slide of three Anorthoneis sp. (I’ll come back to the name on the slide label in a minute) in between 2 Paralia diatoms. Location given as The Warren, (mof) River Exe. Presumably this is Dawlish Warren, a massive sand spit and National Nature Reserve that stretches across the mouth of the River Exe in South Devon, UK. Cover gauge 0.004” (0.10mm) – thin coverslip. 2 1895 (presumably February 1895). Prepared by William Allott Firth. Olympus BHB microscope using 450nm LED light. 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. 22 images stacked in Zerene (Pmax). Label on the back says ”1 valve very dim, difficult to find or to see. Rattray p. 151. AS LVIII, 25,26. 2mm yes.”.
Back to the name. The slide has these labelled as Coscinodiscus cocconeiformis. Coscinodiscus cocconeiformis A.W.F.Schmidt 1878. Published in: Schmidt, A.[W.F.] (1878). Atlas der Diatomaceen-kunde Series II: Heft 15. pp. pls 57-60. Aschersleben: Verlag von Ernst Schlegel. Plate 58, Figures 25,26,28. However these are not Coscinodiscus cocconeiformis (also known as Diplomenora cocconeiformis (A.W.F.Schmidt) K.L.Blazé 1984). They are Anorthoneis sp.. Top right looks to be Anorthoneis excentrica (raphe valve), the other two maybe Anorthoneis hummii (sternum valves). These two have more roundish/transapically elongated areolae than A. excentrica. For now I will leave them as ‘Anorthoneis sp., River Exe’.
Anorthoneis excentrica (Donkin) Grunow 1868. Published in: 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. Page 10, adnot. Original name: Cocconeis excentrica Donkin, 1858. Original description: (of Cocconeis excentrica Donkin, 1858) Donkin, A.S. (1858). On the marine diatomaceae of Northumberland with a description of eighteen new species. Transactions of the Microscopical Society of London, 6: 12-34, pl. III. Page 25, Plate 3, Figure 11.
Also see: Pennesi, C., Majewska, R., Sterrenburg, F.A., Totti, C. & de Stefano, M. (2018), Taxonomic revision and morphological cladistics analysis of the diatom genus Anorthoneis (Cocconeidaceae), with description of Anorthoneis arthus-bertrandii sp. nov.. Phytotaxa 336 (3): 201–238. https://doi.org/10.11646/phytotaxa.336.3.1