Phylum: Charophyta   Family: Desmidiaceae

Euastrum elegans  J. Ralfs 1848

Semicells ovate-pyramidate, basal angles subrectangular, retuse, small sub-apical lobe, lateral sides concave, apex broadly rounded with a deep and narrow median incision. The basal angles and sub-apical lobes support papillae. Sinus deep and closed for the most part. Above the isthmus is a protuberance comprising three granules.
Cell dimensions: L: 27-40 µm; B: 17-22 µm; Is: 4.5-6.5 µm; Th: 10-14.5 µm; L/B: 1.4-1.7.
Zygospore globose with long, simple spines. Size minus spines: 25-28 µm; spines: 11-12 µm; overall: 47-53 µm.
Widespread and common in acidic, mesotrophic habitats such as moorland pools and bogs.

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. (1905) A Monograph of the British Desmidiaceae, Volume 2.