Phylum: Charophyta   Family: Desmidiaceae

Tetmemorus laevis J. Ralfs 1848

West & West (1904: 222) describe the cells thus: “… semicells very gradually attenuated to the apices; apex fairly broad and rounded, with a deep median incision; cell-wall minutely punctate; chloroplasts with a median series of 3-5 pyrenoids; semicells in side view more attenuated than in front view, especially near the apex.”
Cell dimensions: L: 71-102 µm; B: 20-31 µm; L/B: 3.0-4.6.
West & West (l.c.) note: “T. laevis has a world-wide distribution; it is found from sea-level to the snow-line, and also in the waters of warm and hot springs. It is rarely found in the freshwater plankton.” It is common in the Outer Hebrides in moorland pools and bogs.

References: 
Coesel, P.F.M. & Meesters, K.J. (2023 second edition). Desmids of the Lowlands.
Van Westen, M.C. (2024). Sieralgen in Drenthe.