An arrangement of five Biddulphia reticulata from Sumatra. The two on the left are top side facing upwards, the three on the right have their rims to the coverslip (underside view). I think this was made by WA Firth (probably, not named but similar style) but am not 100%. Olympus BHB microscope using 450nm LED light. 40x Leitz Pl Apo NA 1.00 objective, oil immersion. Olympus Aplanat Achromat condenser, oblique lighting, oil immersion. 2.5x Nikon CF PL photoeyepiece. 11mm removed from the tube the camera. Monochrome converted Nikon d850 camera. 67 images stacked in Zerene (Pmax).
Biddulphia reticulata Roper 1859. Published in: Roper, F.C.S. (1859). On the genus Biddulphia and its affinities. Transactions of the Microscopical Society of London 7: 1-24, pl. 1-2. Page 4, Plate 2, Figures 13-15. This name is currently regarded as a synonym of Pseudictyota reticulata (Roper) P.A.Sims & D.M.Williams. Source of synonymy: Sims, P.A., Williams, D.M. & Ashworth, M.[P.] (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): 1-56, 156 figs, 2 text-figs.