Phylum: Charophyta   Family: Desmidiaceae

Micrasterias oscitans J. Ralfs 1848

A distinct species with the semicells in two parts. The polar lobe with a slightly convex apex with a hint of a saddle, the lower side concave and joining the lower lobe with a broad invagination. The lateral lobe occupies two-thirds of the semicell and is subfusiform. The lateral angle has two dentitions, the apical angle has one.
Cell dimensions: (2) L: 150-152 µm; B: 126-133 µm; Is: 24-27 µm; L/B: 1.13-1.21.
West & West (1905: 78) record it as exceedingly rare, occurring principally in upland areas, in moorland pools and bogs. Just a single sample has been found in the Outer Hebrides.

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