Two examples of Coscinodiscus excavatus var. biocellatus (spelt ‘excavata‘ and ‘bicellata‘ on the slide). Prepared by Flatters and Garnett Ltd. Olympus BHB microscope using 450nm LED light. 40x Leitz Pl Apo NA 1.00 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, oblique lighting. 2.5x Nikon CF PL photoeyepiece. 11mm removed from the tube the camera to increase the field of view. Monochrome converted Nikon d850 camera. 106 images stacked in Zerene (Pmax).
Coscinodiscus excavatus var. biocellatus Grunow 1884. Published in: Grunow, A. (1884). Die Diatomeen von Franz Josefs-Land. Denkschriften der Kaiserlichen Akademie der Wissenschaften. Mathematisch-Naturwissenschaftliche Classe, Wien 48(Abt. 2): 53-112, 5 pls. Page 73, no figure (as ‘biocellata‘).