Phylum: Charophyta   Family: Desmidiaceae

Xanthidium cristatum L.A. de Brébisson ex J. Ralfs 1848

First described by Brébisson in Ralfs (1848: 115, pl. 19: 3) and illustrated by Jenner. Similar to X. fasciculatum but that species has the central protuberances ornamented in the form of coronas. Also, the lower spines are twinned (single in X. cristatum).
Overall dimensions: L: 60-77 µm; B: 55-68 µm; Is: 13-15 µm.
The British distribution is biased towards the north-west where it is found in the plankton of lochs but also upland pools.

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. (1912). A Monograph of the British Desmidiaceae, Volume 4.