Periphyton from a small peat lake: pH = 6,5; Сm(NO₃⁻) ~ 90 ppm.
Magnification of all photos: 1000× (oil immersion)
Habitat: water squeezed from Spirogyra growing along the edge of a lake.
Using stage micrometer for calibration, valve estimated to be about 64 µm long and 21 µm wide.
Somewhat soft and bendy, but snaps when pressed against. Likely a juvenile.
Magnification of photos: 100×, 200×, 200×, 200×, 200×, 400×, 400×, 400×, 400×, 400×
Habitat: muddy water, collected from the bank of a wide stream.
Photo taken with a Celestron PentaView Digital Microscope. According to their website, the FOV at 100× is 600 µm.
https://www.celestron.com/blogs/knowledgebase/what-is-my-digital-microscopes-field-of-view
Very large: estimated to be about 200 µm.
The first observation of Cymbella mexicana was made in January 2021 on diatom strew slides (mounting media Naphrax) prepared from sediment/sand collected from the Havel river's shallow zone at Premnitz/Brandenburg. Length: 55-125 µm; width: 19 - 35 µm. Striae: 7-8/10 µm. The single central stigma, the size and the coarse dots makes this species easily determinable.
central area constricted
parallel striae
rostrate to subcapitate apices
narrow, slightly panduriform valves