Phylum: Charophyta   Family: Desmidiacea

Pleurotaenium trabecula C. Nägeli 1849

First described by Nägeli (1849: 104) without illustration. West & West (1904: 209, pl. 30: 11-13) note: “… semicells with one basal inflation, rarely with a second slight undulation above it, almost cylindrical, gradually attenuated, towards the apices, lateral margins almost straight, generally faintly convex; apices rounded-truncate, destitute of tubercles; cell-wall punctate.”
Cell dimensions: L: 240-520 µm; B: 26-46 µm; L/B: 11-16.
Frequently recorded. Found in mildly acidic habitats such as moorland pools and bogs, also in shallow loch-margins.

References: 
Coesel, P.F.M. & Meesters, K.J. (2023 second edition) Desmids of the Lowlands.
Nägeli, C. (1849) Gattungen einzelliger Algen, physiologisch und systematisch bearbeitet. Neue Denkschriften der Allg.
Ruzicka, J. (1977) Die Desmidiaceen Mitteleuropas, Volume 1, Part 1.
West, W. & West, G.S. (1904) A Monograph of the British Desmidiaceae, Volume 1.