Phylum: Charophyta   Family: Desmidiaceae

Staurastrum bulbosum var. cyathiforme (W. & G.S. West) P.F.M. Coesel & K.J. Meesters 2013

First described and illustrated by West & West (1895: 77, pl. 9: 2) as Staurastrum gracile var. cyathiforme. It was later moved to its current position by Coesel & Meesters (2013: 79, pl. 102: 2-5). Differs from the nominate variety in have some of its dentition bifurcate. It can also have more than two spines at the ends of the processes (rarely more than three).
Cell dimensions: L: 52-65 µm; B: 70-102 µm; Is: 11-13 µm.
This variety seems to be commoner than the nominate and occupies the same habitat type.

References: 
Coesel, P.F.M. & Meesters, K.J. (2013) European Flora of the Desmid Genera Staurastrum and Staurodesmus.
West, W. & West, G.S. (1895) A contribution to our knowledge of the freshwater algae of Madagascar.