Two slides of Aulacodiscus sp. from Oamaru. Prepared by Arthur Cottam. Olympus BHB microscope using 450nm LED light.
First, three diatoms, and labelled Aulacodiscus rattrayi, subrimosus, and crux var. subsquamosa.
40x 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. 117 images stacked in Zerene (Pmax).
Names for these. Here’s the details for the names given.
Aulacodiscus rattrayi. Aulacodiscus rattrayi Grove & Sturt 1887. Published in: Grove, E. & Sturt, G. (1887). On a fossil marine diatomaceous deposit from Oamaru, Otago, New Zealand. Appendix. Journal of the Quekett Microscopical Club, Series 2 3(19): 131-148, pls 10-14. Page 139, Plate XI [11], Figure 29.
Aulacodiscus subrimosus. Lower left one? Aulacodiscus subrimosus Grunow 1888. Published in: Schmidt, A.[W.F.] (1888). Atlas der Diatomaceen-kunde Series III (Heft 31-32). pp. pls. 121-128. Leipzig: Fuess Verlag (R. Reisland). Plate 124, Figures 4,5.
Aulacodiscus crux var. subsquamosa. Lower right one? Aulacodiscus crux var. subsquamosus Grunow 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 350, Plate VI [6], Figure 8 (as ‘subsquamosa‘).
However none of these look like A. rattrayi to me. What about the others? For some reason I am struggling to get good matches for these which consistent between different sources. So rather than making a fool of myself I am going to leave these as Aulacodiscus from Oamaru for now.
Second, another slide again from Oamaru.
This one is labelled as Aulacodiscus huttonii and angulatus. 40x Leitz Pl Apo NA 1.4 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, oblique lighting. 2.5x Nikon CF PL photoeyepiece. 11mm removed from the tube the camera to increase the field of view. Monochrome converted Nikon d850 camera. 73 images stacked in Zerene (Pmax).
Names for these. Here’s the details for the names given.
Aulacodiscus huttonii. Aulacodiscus huttonii Grove & Sturt 1887. Published in: Grove, E. & Sturt, G. (1887). On a fossil marine diatomaceous deposit from Oamaru, Otago, New Zealand. Appendix. Journal of the Quekett Microscopical Club, Series 2 3(19): 131-148, pls 10-14. Page 140, Plate XII [12], Figure 31. This name is currently regarded as a synonym of Aulacodiscus janischii Grove & Sturt.
Aulacodiscus angulatus. Aulacodiscus angulatus Greville 1863. Published in: Greville, R.K. (1863). Descriptions of new and rare Diatoms. Series IX. Transactions of the Microscopical Society, New Series, London 11: 63-76, pls IV, V. Page 71, Plate 5, Figure 15.
Again, though, none of these look particularly like A. huttonii to me (although the smaller ones on the left do look quite like A. angulatus). Again, I am not 100% on them, so will also leave this one as Aulacodiscus from Oamaru.
Two lovely slides with Aulacodiscus diatoms from Oamaru, but I am struggling with specific species for most of them.