Sphaerastrum fockii (Archer, 18969) emend. Mikrjukov, 1996

Diagnosis: Cells 9-32 µm in diameter, average 22 µm, surrounded by a not always clearly visible thick mucus layer. Cytoplasm and mucus not or hardly separated from each other.  Numerous needle shaped spicules are tangentially or sub-tangentially oriented in the mucus layer, 30-40 µm long, of uniform thickness. Several contractile vacuoles present, sometimes bulging. Cells may form colonies by aggregating of 10-12 individuals connected by cytoplasmic bridges; mucus cover and spicules apply in this case on the entire colony.

Ecology: Freshwater. Between water plants. Distribution: Europe, South-America.