Phylum: Charophyta   Family: Desmidiaceae

Sphaerozosma filiforme J. Ralfs 1848

First described by Ralfs (1848: 209) but later Roy & Bisset (1886: 242) moved it to Onychonema, noting: “This species, so long considered a Sphaerozosma is evidently a true Onychonema.” John & Williamson (2009: 177) note: “This taxon is contentious insofar as some authorities would assign it to the genus Sphaerozosma with which clearly it has an affinity, but both West et al. (1923, p. 216) and Croasdale et al. (1994, p. 158) point out differences between the genera which hinge on the length, disposition and method of attachment of the apical processes, with short knobs close together and linked to similar knobs in the case of Sphaerozosma, but with long rods widely spaced and linking with the body of the adjoining semicell in the case of Onychonema.” European workers have adopted the genus Sphaerozosma: (Kouwets 1999: 102); Coesel & Meesters (2023: 257).
Cell dimensions: L: 9-15 µm; B: 10-19 µm; Th: 7-8 µm; L/B: c.1.00.
Found in acidic moorland pools and disused peat-cuttings but rarely encountered.

References: 
Coesel, P.F.M. & Meesters, K.J. (2023 second edition) Desmids of the Lowlands.
John, D.M. & Williamson, D.B. (2009) A Practical Guide to the Desmids of the West of Ireland.
Kouwets, F.A.C. (1999) A check-list of desmids (Chlorophyta, Zygnemaphyceae) of France.
Ralfs, J. (1848) The British Desmidieae.
Roy, J. & Bisset, J.P. (1886) Notes on Japanese desmids. - No. I.
West, W., West, G.S. & Carter, N. (1923) A Monograph of the British Desmidiaceae, Volume 5.