Auliscus peruvianus on a slide by Watson and Sons Ltd. Single example, mounted with the rim upwards towards the coverslip (underside view). Yellowed mountant. Olympus BHB microscope using 450nm LED light. 63x 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. 67 images stacked in Zerene (Pmax).
Auliscus peruvianus (F.Kitton ex Ralfs) Greville 1862: 25. See: Greville, R.K., 1861-1866. Description of new and rare, diatoms I-XX. (Trans. Microscop. Soc.) London (Reprint 1968). 206 pp., Bibliotheca Phycologica 6. This name is currently regarded as a synonym of Pseudauliscus peruvianus (Kitton ex Ralfs) A.W.F.Schmidt 1875. Published in: Schmidt, A.[W.F.] (1875). Atlas der Diatomaceen-kunde. Series I: Heft 8. pp. pls 29-32. Aschersleben: Verlag von Ernst Schlegel. Plate 32, Figure 29. Homotypic synonyms: Eupodiscus peruvianus Kitton ex Ralfs 1861, Auliscus peruvianus (F.Kitton ex Ralfs) Greville 1862.
There’s an interesting mention of this species in: Mills, L.G. (1881), XII.—Diatoms from Peruvian Guano. Journal of the Royal Microscopical Society, 1: 865-867. https://doi.org/10.1111/j.1365-2818.1881.tb05915.x; “Auliscus peruvianus which was not unusual in the past, is now so rare, that a single valve, from a large quantity of material, would give me some surprise. I have not had a specimen from the preparations of the last six years. Two figures of this diatom were given by the late Dr. Greville in the ‘Trans. Micr. Soc. Lond.,’ x. (1862).”. It therefore seems like there are some temporal variations in this material, with A. peruvianus being mainly found in earlier samples.