An arrangement of three Orthoneis diatoms (slide says O. splendida, but more on this in a minute) from Nagasaki, Japan. Prepared by WH Darlaston. Olympus BHB microscope using 450nm LED light. As well as the arrangement, I selected one 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. 27 images stacked in Zerene (Pmax).
Back to the name. Orthoneis splendida (Gregory) Grunow 1868. This name is currently regarded as a synonym of Mastogloia splendida (Gregory) H.Pergallo 1888. Published in: Peragallo, H. (1888). Diatomées de la Baie de Villefranche (Alpes Maritimes). Bulletin de la Société Histoire Naturelle de Toulouse 22: 13-100, 6 plates [I=VI], 2 tables. Page 51.
However I don’t think this is correct though – the central lines look wrong.
This is a Mastogloia sp. of some type. Maybe Mastogloia fimbriata? Mastogloia fimbriata (Brightwell) Grunow 1863. Published in: Grunow, A. (1863). Über einige neue und ungenügend bekannte Arten und Gattungen von Diatomaceen. Verhandlungen der kaiserlich-königlichen zoologisch-botanischen Gesellschaft in Wien 13: 137-162, 2 pls. Page 156. I’ll leave it as Mastogloia sp. for now though.