Phylum: Charophyta   Family: Desmidiaceae

Staurastrum diacanthum A. Lemaire 1890

First described and illustrated by Lemaire (1890: 4, fig. 2). Closely related to Staurastrum paradoxum, it is characterised by two large spines near the base of the processes on the dorsal side.
Cell dimensions: L. 30-50 µm, B. 30-50 µm, Is. c.9 µm.
A rare taxon found in vegetated loch-margins and moorland pools.

References: 
Coesel, P.F.M. & Meesters, K.J. (2013). European Flora of the Desmid Genera Staurastrum and Staurodesmus.
Lemaire, A. (1890). Liste des Desmidacées observées dans quelques lacs des Vosges et aux environs d'Étival.