An arrangement of three Pleurosigma balticum (now known as Gyrosigma balticum). Mounted in Styrax and dated August 1943. Prepared by Samuel Henry Meakin. Olympus BHB microscope using 450nm LED light. I imaged the middle one from the arrangement at higher magnification. 40x Leitz Pl Apo NA 1.00 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, oblique lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 37 images stacked in Zerene.
Pleurosigma balticum (Ehrenberg) 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 8, Plate 2, Figure 1. This name is currently regarded as a synonym of Gyrosigma balticum (Ehrenberg) Rabenhorst. Gyrosigma balticum (Ehrenberg) Rabenhorst 1853. Published in: Rabenhorst, L. (1853). Die Süsswasser-Diatomaceen (Bacillarien.): für Freunde der Mikroskopie. pp. [1]-xii, [1]-72, 10 plates [I–X]. Leipzig: Eduard Kummer. Page 47, Plate 5, Figure 6.