Two examples of Aulacodiscus mölleri from Maryland. Described on the slide as ‘very rare’. Prepared by Norman H Seward of Melbourne. Olympus BHB microscope using 450nm LED light. As well as the pair, I imaged the right hand side 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. 11mm of the tube to the camera removed to increase the field of view. Monochrome converted Nikon d850 camera. 39 images stacked in Zerene (Pmax). 92 images stacked in Zerene (Pmax).
Aulacodiscus moelleri Grunow 1876. Published in: Schmidt, A., Schmitz, M., Fricke, F., Müller, O., Heiden, H. & Hustedt, F. (1874-1959). Atlas der Diatomaceen-Kunde. 4 Bands, pls. 1-480. Leipzig. Plate 33, Figure 14. This name is currently regarded as a synonym of Aulacodiscus margaritaceus var. moelleri (Grunow) Rattray 1888. Published in: Rattray, J. (1888). A revision of the genus Aulacodiscus Ehrb. Journal of the Royal Microscopical Society 8(3): 337-382, 3 pls [V-VII]. Page 352. I am using the Aulacodiscus mölleri spelling here (I like my umlauts).