Phylum: Charophyta   Family: Desmidiaceae

Pleurotaenium coronatum (J. Ralfs) L. Rabenhorst 1868

First described and illustrated in Ralfs (1848: 217, pl. 35: 6) as Docidium coronatum. Rabenhorst (1868: 143) later moved it to Pleurotaenium. It has a whorl of prominent apical tubercles (or granules) like a crown, hence the specific epithet. It is very similar to P. nodulosum but with barely taper cells towards the apices and with larger tubercles. Intermediates are difficult to determine.
Cell dimensions: L: 400-600 µm; B: 40-65 µm; L/B: 8-12.
An acidophile of moorland pools and Sphagnum bogs, but rarely recorded.

References: 
Coesel, P.F.M. & Meesters, K.J. (2023 second edition) Desmids of the Lowlands.
Rabenhorst, L. (1868) Flora europaea algarum aquae dulcis et submarinae. Sectio III. Algae chlorophyllophyceas, melanophyceas et rhodophyceas complectens.
Ralfs, J. (1848) The British Desmidieae.
Ruzicka, J. (1977) Die Desmidiaceen Mitteleuropas, Volume 1, Part 1.
West, W. & West, G.S. (1904) A Monograph of the British Desmidiaceae, Volume 1.