Hyalosphenia penardi Lauterborn, 1908
Diagnose: shell transparent, colorless, yellow or brown, elliptical with a strongly curved, nearly semi-circular pseudostome; fundus broadly rounded; surface without structure; plasma usually partly filling the shell, with some epipodia; shell strongly compressed, especially towards the aperture; nucleus globular with granules? (see drawing).
Dimensions: L 180 µm, B 70 µm.
Ecology: this species has been found in the Upper Rhine in Germany, between diatoms. Food: mainly diatoms.