Phylum: Chlorophyta   Family: Chlorellaceae

Closteriopsis acicularis  (Chodat) J.H. Belcher & Swale

Common in lakes and lochs, especially with water plants and plankton

References: 
John, D.M., Whitton, B.A. & Brook, A.J. (2011) The Freshwater Algal Flora of the British Isles