Slide labelled as Amphitetras decora but I think this is Amphitetras elegans (more in a minute on this), from Newport, California, USA. Three examples in an arrangement. Prepared by JA Long. Olympus BHB microscope using 450nm LED light. 20x Nikon Plan Apo NA 0.65 objective. Olympus Aplanat Achromat condenser, oblique lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 48 images stacked in Zerene (Pmax).
Ok, the name. I can’t find the name A. decora. However I think this is Amphitetras elegans Greville 1866. Published in: Greville, R.K. (1866). Descriptions of new and rare Diatoms. Series XVIII. Transactions of the Microscopical Society, New Series, London 14: 1-9, pls I, II. Page 9, Plate 2, Figure 24.