Two examples of Stictodiscus parallelus. Cracked coverslip. Yellowed mountant with some issues. Prepared by Flatters and Garnett Ltd. 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. 24 images stacked in Zerene (Pmax).
Stictodiscus parallelus (Ehrenberg) Castracane 1886. Published in: Castracane, [C.A.] F. (1886). Report on the Diatomaceae collected by H.M.S. Challenger during the years 1873-76. In: Report on the Scientific Results of the Voyage of H.M.S. Challenger during the years 1873-76. Botany. Vol. II. (Murray, J. Eds), pp. [1]-178. Page 114. Presumably, two variants present on the slide.