Phylum: Charophyta Family: Desmidiaceae
Xanthidium smithii W. Archer 1860
A infrequently recorded species, preferring acidic conditions. Well suited to the lochs and bogs of north and west Scotland where it is most frequent. The length of spines varies considerable but would seem to be between populations rather than within.
References:
Archer, W. (1860) Description of a new species of Cosmarium, and of a new species of Xanthidium.
John, D.M. & Williamson, D.B. (2009) A Practical Guide to the Desmids of the West of Ireland.
West, W. & West, G.S. (1912) A Monograph of the British Desmidiaceae, Volume 4.
Coesel, P.F.M. & Meesters, K.J. (2007) Mesotaeniaceae and Desmidiaceae of the European Lowlands.