A selection of Plagiogramma elongatum from Rio de Janeiro, Brazil. The one at the right hand side is much lower in the mountant than the others. Prepared by William Allott Firth (but no name on the slide, basing this on style and handwriting). Olympus BHB microscope using 450nm LED light. As well as the selection, I imaged one 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. 41 images stacked in Zerene (Pmax). Apical pore field are really well defined in this preparation.
Plagiogramma elongatum Greville 1866. Published in: Greville, R.K. (1866). Descriptions of new and rare Diatoms. Series XX. Transactions of the Microscopical Society, New Series, London 14: 121-130, pls XI, XII. Page 121, Plate XI [11], Figures 1,2.