Auliscus radiatus from North Carolina. Single example on the slide. Prepared by Samuel Henry Meakin. Mounted in Hyrax and dated October 1932. 63x Leitz Pl Apo 1.4 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, oblique lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 33 images stacked in Zerene (Pmax). Nice high contrast mount. I ended up using less sharpening than usual for this one – the normal settings for the 63x objective resulted in a image which I thought looked a little harsh, I think due to the high contrast and well prepared mounting.
This is also known as Pseudauliscus radiatus. P. radiatus is currently regarded as a synonym of Mastodiscus radiatus (Bailey) A.K.S.Prasad & Nienow. Published in: Sims, P.A., Williams, D.M. and Ashworth, M. (2018) Examination of type specimens for the genera Odontella and Zygoceros (Bacillariophyceae) with evidence for the new family Odontellaceae and a description of three new genera. Phytotaxa 382: 1-56.