A strew slide of Pleurosigma formosum (and few other different types of diatoms). Mainly fragments. Really pretty rainbow colouration of the strew under white light illumination (often get coloured effects with Pleurosigma diatoms, although not always as varied a range of colours as this). Prepared by Flatters and Garnett Ltd. Olympus BHB microscope using 450nm LED light. As well as the strew I did find and image one intact one using the 20x Nikon Plan Apo NA 0.65 objective. Olympus Aplanat Achromat condenser, oblique lighting. 2.5x Nikon CF PL photoeyepiece. 11mm removed from the tube to the camera to increase the field of view. Monochrome converted Nikon d850 camera. 33 images stacked in Zerene (Pmax).
Pleurosigma formosum W.Smith 1852. Published in: Smith, W. (1852). Notes on the Diatomaceae with descriptions of British species included in the genus Pleurosigma. Annals and Magazine of Natural History, Series 2 9: 1-12, 2 pls. Page 5, Plate 1, Figure 1.
Origin of species name; Adjective (Latin), beautiful. Very apt, an elegant diatom.