Phylum: Charophyta Family: Desmidiaceae
Cosmarium quadratulum (F.Gay) De Toni
One of many very small Cosmarium species which are difficult to define and lead to some confusion. An acidophile that is possibly rare but also under-recorded
References:
Coesel, P.F.M. & Meesters, K.J. (2007) Mesotaeniaceae and Desmidiaceae of the European Lowlands