Phylum: Chlorophyta   Family: Selenastraceae

Quadrigula closterioides (Bohlin) Printz 1916

First described and illustrated by Bohlin (1897: 18, pl. I: 23-24) as Nephrocytium closterioides. It was later moved by Printz (1916: 49, pl. 4: 110-116) to its current position. The specific epithet comes from its similarity to the desmid genus Closterium.
Cells: dimensions: L: 20-30 µm; B: 2-6 µm.
John et al. (2011: 467) note: “… not uncommon in the plankton of Scottish lochs, …”.

References: 
Bohlin, K.(1897). Die Algen der ersten Regnell'schen Expedition. I. Protococcoideen.
John, D.M., Whitton, B.A. & Brook, A.J. (2011 second edition). The Freshwater Algal Flora of the British Isles.
Printz, H. (1916). Beiträge zur Kenntnis der Chlorophyceen und ihrer Verbreitung in Norwegen.