Two Pinnularia diatoms from Birge Pond, Bristol, Connecticut. Label says Pinnularia acrosphaeria (var. turgidula), more on that in a minute. Mounted in Hyrax. No makers name, but prepared by JA Long. Olympus BHB microscope using 450nm LED light. I then imaged them both with a 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. Image stacks prepared in Zerene (Pmax).
Pinnularia formica (the long thin one). 9 images stacked. Previous name Navicula formica. Pinnularia formica (Ehrenberg) R.M.Patrick 1966. Published in: Patrick, R.[M.] & Reimer, C.W. (1966). The diatoms of the United States exclusive of Alaska and Hawaii. Volume 1: Fragilariaceae, Eunotiaceae, Achnanthaceae, Naviculaceae. Monographs of the Academy of Natural Sciences of Philadelphia 13: 1-688. Page 627, Plate 61, Figures 1,2.
Pinnularia turgidula (the smaller one). 11 images stacked. Pinnularia turgidula (Grunow ex Cleve) Kulikovskiy, Lange-Bertalot & Metzeltin 2010: 363. Published in: Kulikovskiy, M., Lange-Bertalot, H. & Metzeltin, D. (2010). Specific rank for several infraspecific taxa in the genus Pinnularia Ehrenb. Algologia 20(3): 357-367. Page 363. Basionym: Pinnularia acrosphaeria var. turgidula Grunow ex Cleve (hence the name on the slide).