Hyalosphenia punctata  Penard, 1891

Diagnosis: 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: According to Penard (1891): Shell length 55—90 µm. Opravilova (1974): Lenght 69—93 µm. Török (2001): Length 35—95 µm (mean 75 µm). My measurements: Length 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.

Geographical distribution: Ecuador, India, Russia, Europe.

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