Hyalosphenia punctata Penard, 1891
Diagnose: Shell transparent, colorless, yellow or brown, broad oval with a slit-like aperture; this aperture is nearly as broad as the shell; in side view the fundus is broadly rounded, tapering to the aperture, which can be open or closed; shell with an Arcella-like structure, composed of small organic building units; pseudostome with a narrow lip; plasma usually partly filling the shell, sometimes with some epipodia; nucleus globular with a large nucleolus.
Dimensions: Penard 55-90 µm, Opravilova (1974) 69-93 µm, Török (2001) 35-95 µm (mean 75 µm). My measurements 64-72 µm.
Ecology: This species has been found in very different types of water, like deep alpine lakes (Penard, 1891, 1902), swamps (Penard, 1902) and running waters (Opravilova, 1974,1980, Török, 2001). I have found this remarkable and rare species in the sediment of a ditch in nature reserve Naardermeer in the Netherlands, where it occurred in considerable numbers. Food: bacteria, green algae and diatoms.
Remarks: Júlia Török (2001) states that this species possibly belongs to the genus Nebela, because of its shell structure.