Phylum: Charophyta   Family: Desmidiaceae

Cosmarium quinarium P. Lundell 1871

A widespread species but never common. Found in the tychoplankton of mainly oligotrophic lochs and lochans.

References: 
Lundell, P. (1871) De desmidiaceis quae in Suecia inventae sunt, observationes criticae
John, D.M. & Williamson, D.B. (2009) A Practical Guide to the Desmids of the West of Ireland
Kouwets, F.A.C. (in manuscript) European Flora of the Desmid Genus Cosmarium