Examples of Pleurosigma decorum var.? from Paama Island, New Hebrides (Paama is a small island in Malampa Province, Vanuatu). Some mountant issues, including yellowing. Some diatom movement. Prepared by William Allott Firth. Olympus BHB microscope using 450nm LED light. As well as the group I imaged the pale one on the left using the 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. 43 images Pmax. Very pale. Underside view, with the rim upwards towards the coverslip.
Pleurosigma decorum W.Smith 1853. Published in: Smith, W. (1853). A synopsis of the British Diatomaceae; with remarks on their structure, function and distribution; and instructions for collecting and preserving specimens. The plates by Tuffen West. In two volumes. Vol. I. pp. [i]-xxxiii, 1-89, pls I-XXXI. London: John van Voorst, Paternoster Row. Page 63, Plate XXI [21], Figure 196.