Two strew slides from Moreno shale, Y Canyon, Samples 398 B and B2. Fossil marine material. Diatomite sample from H Jay Margolis. Diatom sample from the collection of Colonel William D Fleming, US Army, MD FRMS. Mounted in Pleurax and dated May 2026. Slides prepared by Michel Haak. Olympus BHB microscope using 450nm LED light. As well as the wider field of the strews, I selected some diatoms for imaging at higher resolution. 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. Images stacked in Zerene (Pmax).
Both slides had lots of examples of Glorioptychus callidus which was interesting to see.
First the strew of sample 398 B.
Rattrayella churchii Hanna 1934. Published in: Hanna, G.D. (1934). Additional notes on diatoms from the Cretaceous of California. Journal of Paleontology 8: 352-355. Page 355, Plate 48, Figures 3-5. This name is currently regarded as a synonym of Eupodiscus churchii (Hanna) P.A.Sims 2001. Published in: Sims, P.A. (2001). The genus Praetriceratium gen. nov.: a survey of eupodiscoid genera with a sipho marginalis. Diatom Research 16(2): 399-416. Page 407, Figures 35,36.
Kentrodiscus blandus J.A.Long, Fuge & Js.Smith bis 1946. Published in: Long, J.A., Fuge, D.P. & Smith, J. (1946). Diatoms of the Moreno Shale. Journal of Paleontology 20(2): 89-118, 2 figures, plates 13-19. Page 107, Plate 18 Figure 14, Plate 19 Figures 3-5.
Reasonably sure with both of these.
Secondly, the slide of Sample 398 B2. A few more question marks here.
Auliscus sp. (Auliscus dilectus ? ). Underside view with the rim upwards towards the coverslip. Quite deep in the mountant. Very faint markings – less than ideal stacking. Auliscus dilectus J.A.Long, Fuge & Js.Smith bis 1946. Published in: Long, J.A., Fuge, D.P. & Smith, J. (1946). Diatoms of the Moreno Shale. Journal of Paleontology 20(2): 89-118, 2 figures, plates 13-19. Page 99, Plate 15, Figure 14. Somewhat tentative, and not a great looking stack.
Actinoptychus packii Hanna 1927. Original description: Hanna, G. D. (1927). Cretaceous diatoms from California. Occasional Papers of the California Academy of Sciences. 13: 5-49 [including 5 plates]. Page 12, Plate 1, Figs 1-3 [as ‘packi’].
Aulacodiscus sp. (A. brownei ? ). 5 processes, underside view with the rim upwards. Only one like it on the slide. Looks a bit like Aulacodiscus brownei, however this has 5 processes. Aulacodiscus brownei Norman ex 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 (as ‘A. Browneii (Norman, MS.)’). Very tentative on this one though.
Aulacodiscus sp. (A. pugnalis ? ). 4 processes. Aulacodiscus pugnalis Hanna 1927. This diatom is referred to in Hanna, G.D. (1927). Cretaceous diatoms from California. Occasional Papers of the California Academy of Sciences 13: 5-[49]. Pages 14,15, Plate 1, Figures 6,7. In this it is spelt ‘pungalus‘ a couple of times as well as ‘pugnalis‘. In the WoRMS database it states that the accepted name is A. pugnalus (see here). This name is currently regarded as a synonym of Aulacodiscus archangelskianum var. pugnalis (Hanna) J.A.Long, Fuge & Js.Smith bis 1946. Published in: Long, J.A., Fuge, D.P. & Smith, J. (1946). Diatoms of the Moreno Shale. Journal of Paleontology 20(2): 89-118, 2 figures, plates 13-19. Page 97, Plate 13, Figure 12. For another example on this site, and more on the name, see here. Bit tentative with this one.