Phylum: Chlorophyta   Family: Sphaerocystidaceae

Sphaerocystis planctonica (A.A. Korshikov) P. Bourrelly 1974

First described and illustrated by Korshikov (1953: 219, fig. 158 a-c) as Palmellocystis planctonica. It was later moved to its current genus by Bourrelly (1974: 9).
Cell dimensions: B: 4-9 µm. Coenobia usually of 4, 8 or 16 celled.
Thought to be widespread in Britain, usually in the plankton. Can also be found in flowing water.

References: 
Bourrelly [in] Fott, B. (1974). Taxonomie der palmelloiden Chlorococcales (Familie Palmogloeaceae).
John, D.M., Whitton, B.A. & Brook, A.J. (2011 second edition). The Freshwater Algal Flora of the British Isles.
Korshikov, A.A. (1953). Viznachnik prisnovodnihk vodorostey Ukrainsykoi RSR. Pidklas Protokokovi (Protococcineae). Bakuol'ni (Vacuolales) ta Protokokovi (Protococcales).