Aulacodiscus margaritaceus from Rio de Janeiro. Single example on the slide which has migrated out of the central ring. There’s no makers name, however the style looks a bit like those of WA Firth and even the Barbour brothers, so have put Firth now, but with a question mark. The stickers which says ‘J. Lizars, Optician, Glasgow’ is likely the vendor of the slide not the maker. 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. Monochrome converted Nikon d850 camera. 91 images stacked in Zerene (Pmax).
Aulacodiscus margaritaceus A.W.F.Schmidt, nom. inval. 1876. Published in: Schmidt, A.[W.F.] (1876). Atlas der Diatomaceen-kunde. Series I: Heft 10. pp. pls. 37-40. Aschersleben: Verlag von Ernst Schlegel. Plate 37, Figures 1-7 (as ‘Aulacodiscus margaritaceus Ralfs and varieties’). This name is currently regarded as a synonym of Aulacodiscus margaritaceus Ralfs 1861. Published in: Pritchard, A. (1861). A history of infusoria, including the Desmidiaceae and Diatomaceae, British and foreign. Fourth edition enlarged and revised by J. T. Arlidge, M.B., B.A. Lond.; W. Archer, Esq.; J. Ralfs, M.R.C.S.L.; W. C. Williamson, Esq., F.R.S., and the author. pp. [1]-xii, [1]-968, 40 pls [I-XV]. London: Whittaker and Co.. Page 844.