Aulacodiscus margaritaceus var. tenera from Simbrisk, Russia. Single example on the slide. Prepared by William Allott Firth. Olympus BHB microscope using 450nm LED light. 63x Leitz Pl Apo NA 1.4 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, oblique lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 99 images stacked in Zerene (Pmax).
Aulacodiscus margaritaceus var. tenerus (Witt) 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 353 (as ‘tenera‘). This name is currently regarded as a synonym of Aulacodiscus tenera (Witt) Hustedt 1958. Published in: Schmidt, A.[W.F.] (1958). Atlas der Diatomaceen-kunde. Series VIII (Heft 116). pp. pls 461-464 [F. Hustedt]. Akademie-Verlag. Plate 463, Figures 3,4,10,11. Basionym: Aulacodiscus crux var. tenera Witt.