Phylum: Chlorophyta   Family: Oocystaceae

Oocystis naegelii A. Braun 1855

First described by Braun (1855: 94). Coenobia usually of 2, 4 or 8 cells. Cells are often thick-walled.
Cell dimensions: L: 16-40 µm; B: 10-24 µm; L/B: 1.35-2.0.
Thought to be widespread in Britain, usually in the plankton. John et al (2011: 493) specifically mentions large lochs in Scotland.

References: 
Braun, A. (1855). Algarum unicellularium genera nova et minus cognita praemissis observationibus de algis unicellularibus in genere.
John, D.M., Whitton, B.A. & Brook, A.J. (2011) The Freshwater Algal Flora of the British Isles