Phylum: Charophyta   Family: Desmidiaceae

Micrasterias papillifera var. pseudomurrayi L.J. Laporte 1931

First described and illustrated by Laporte (1931: 92, pl. 5: 57). Differs from the nominate variety in having all the incisions open. There are many intermediate forms which are difficult to determine so how much value can be afforded to var. pseudomurrayi is debatable.
Cell dimensions: L: 100-150 µm; B: 100-140 µm; Is: 15-20 µm; L/B: 1.05-1.15.
Frequently found in acidic mesotrophic waters such as moorland pools and abandoned peat-cuttings.

References: 
Coesel, P.F.M. & Meesters, K.J. (2023 second edition) Desmids of the Lowlands.
Laporte, L.J. (1931) Recherches sur la biologie et la systématique des Desmidiées.
Ruzicka, J. (1981) Die Desmidiaceen Mitteleuropas, Volume 1, Part 2.