Phylum: Charophyta   Family: Desmidiaceae

Tetmemorus granulatus J. Ralfs 1848

First described and illustrated in Ralfs (1848: 147, pl. 24: 2), he notes: “… differs from T. laevis in its less constricted middle and its larger size. Its puncta too are usually very distinct, …”.
Cell dimensions: L: 143-230 µm; B: 25-40 µm; L/B: 4.0-6.0.
This species has a similar distribution to T. laevis and equally as common in the Outer Hebrides.

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. (1904) A Monograph of the British Desmidiaceae, Volume 1.