Phylum: Charophyta   Family: Desmidiaceae

Cosmarium impressulum Elfving 1881

Found in acidic to mildly alkaline waters such as moorland pools, loch-margins and disused peat-cuttings. The original concept is confused and may well represent a species complex.

References: 
West, W. & West, G.S. (1908) A Monograph of the British Desmidiaceae, Volume 3
John, D.M. & Williamson, D.B. (2009) A Practical Guide to the Desmids of the West of Ireland
Coesel, P.F.M. & Meesters, K.J. (2007) Mesotaeniaceae and Desmidiaceae of the European Lowlands