Phylum: Charophyta   Family: Desmidiaceae

Staurastrum subcruciatum M.C. Cooke & A.W. Wills 1887

Wills collected extensively in the neighbourhood of Capel Curig, a mountainous area of North Wales. He made his collections available to Cooke for publication. The shape of the semicells is variable, from triangular to bowl-shaped. The processes are extended and tipped with two quite long spines which are directed upward at about 45 degrees. West, West & Carter (1923: 42) have few records suggesting scarcity or confusion with similar species.
Overall cell dimensions: L: 31-42 µm; B: 36-42 µm; Is: 8-10.7 µm; L/B: 0.8-1.0.
Infrequently recorded. Found oligo-mesotrophic waters such as loch margins, moorland pools and abandoned peat-cuttings.

References: 
Coesel, P.F.M. & Meesters, K.J. (2023 second edition). Desmids of the Lowlands.
Cooke, M.C. (1887). British Desmids. A supplement to British fresh-water algae.
West, W., West, G.S. & Carter, N. (1923). A Monograph of the British Desmidiaceae, Volume 5.