Phylum: Charophyta   Family: Desmidiaceae

Actinotaenium spinospermum (W. Joshua) F.A.C. Kouwets & P.F.M. Coesel 1984

First described by Joshua (1883: 35) as Penium spinospermum. Later moved to Actinotaenium by Kouwets & Coesel (1984: 559). Cells elliptic with a slight median constriction. Cell wall faintly striate with longitudinal series of fine pores.
Cell dimensions: L: 20-30 µm; B: 10-15 µm; L/B: 1.8-2.3.
An oligotrophic species whose status is uncertain due to misidentifications. Found in acidic moorland pools and abandoned peat-cuttings.

References: 
Coesel, P.F.M. & Meesters, K.J. (2023 second edition). Desmids of the Lowlands.
Joshua, W. (1883). Notes on British Desmidieae. No.2.
Kouwets, F.A.C. & Coesel, P.F.M. (1984). Taxonomic revision of the Conjugatophycean family Peniaceae on the basis of cell wall ultrastructure.
Ruzicka, J. (1977). Die Desmidiaceen Mitteleuropas, Volume 1, Part 2.