Phylum: Charophyta   Family: Desmidiaceae

Micrasterias oscitans J. Ralfs 1848

First described and illustrated by Ralfs (1848: 76, pl. 11: 2) in collaboration with Jenner (1845) A flora of Tunbridge Wells. Jenner (1803-1872) was the artist for Ralfs' seminal work. It was thought to be a rare desmid then and West & West (1905: 78, pl. 41: 11-4) note "… is exceedingly rare and we have only found it on three occasions."
Cell dimensions: L: 130-160 µm; B: 120-140 µm; Is: 24-27 µm; L/B: 1.15-1.30.
An acidophile of moorland bogs. Rarely recorded.

References: 
Coesel, P.F.M. & Meesters, K.J. (2023 second edition) Desmids of the Lowlands.
Ralfs, J. (1848) The British Desmidieae.
West, W. & West, G.S. (1905) A Monograph of the British Desmidiaceae, Volume 2.