Phylum: Charophyta   Family: Desmidiaceae

Staurastrum bieneanum L. Rabenhorst 1862

First described by Rabenhorst (1862: no.1410). Coesel & Meesters (2013) comment that the original concept is rather unclear and have therefore based their present concept on West & West (1912). A triradiate taxon, which is as broad as long in face view. The zygospore is roughly globose. The one presented below is distorted.
Cell dimensions: L: 25-37 µm; B: 26-38 µm; Is: 8-10 µm.
Zygospore: minus projections: c.33 µm; overall: c.50 µm.
Found in circumneutral, mesotrophic, waters such as moorland bogs and vegetated loch-margins.

References: 
Coesel, P.F.M. & Meesters, K.J. (2013) European Flora of the Desmid Genera Staurastrum and Staurodesmus.
Rabenhorst, L. (1862) Algen Europa's.
West, W. & West, G.S. (1912) A Monograph of the British Desmidiaceae, Volume 4.