Phylum: Charophyta   Family: Desmidiaceae

Pleurotaenium coronatum var. fluctuatum W. West 1892

First described and illustrated by West (1892: 118, pl. 19: 11). It differs from the nominate variety in having undulate sides extending the full length of the semicell, the undulations becoming less pronounced near the apices. The semicells taper only slightly from base to apex. The apex supports large granules and is slightly raised.
Cell dimensions: L: 500-900 µm; B: 40-60 µm; L/B: 9-16.
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.
Ruzicka, J. (1977). Die Desmidiaceen Mitteleuropas, Volume 1, Part 1.
West, W. (1892).. A contribution to the freshwater algae of west Ireland.