EPITHEMIA TURGIDA

SLIDE: Diatomshop Test slide commemerating Spitta

2025.

This is a freshwater diatom. The areolae are visualized with a 10X n.a. 0.30 objective and better with a 20X objective with an n.a. of 0.46. According to Spitta, this is a diatom which when well resolved shows the areolae clearly. With sufficient n.a. the areolae should be distinct and appear lifted out of the floor. I found this clarity with a 0.70 S-plan objective and oblique lighting. It is a good test of color correction since it is pure white in color. This diatom often contains symbiotic cyanobacteria, capable of fixing nitrogen. This means the organism can tolerate higher nitrogen environments. Its interesting V-shaped raphe empties into a canal inside the organism. With very high magnification, the areolae are complex and not simple round pores.