Staurastrum controversum
Image © André Vanhoof

3-Radiate cell of Staurastrum controversum in frontal view. Notice convergent processes and cell wall furnished with unequally large spines.

Cell dimensions (L x B): 25 x 35 µm

 

 

Desmid of the month
September 2015

Staurastrum controversum

This species belongs to the large group of Staurastra marked by arm-like processes. In cells of St. controversum, when seen in frontal view, the processes are usually distinctly convergent whereas in apical view the processes are clockwise bent.  The cell wall is ornamented with unequally large denticulations and spines. At the base of each process, on its dorsal side, often a pair of extra large, bifurcate spines. St. controversum is characteristic of acidic, oligotrophic water bodies. In the Netherlands it is only incidentally encountered in bogs and moorland pools.

Staurastrum controversum in apical view Staurastrum controversumImage © André Vanhoof

3-Radiate cell of Staurastrum controversum in apical view. Notice processes that are clockwise bent.

Staurastrum controversum in apical view
Image © André Vanhoof

3-Radiate cell of Staurastrum controversum in apical view, showing bifurcate spines at the base of the processes.

Staurastrum controversum, another cellImage © Marien van Westen

Another cell of St. controversum displaying a large, bifurcate spine at the transition of semicell body and arm-like process.

Video © Koos Meesters  

Focus-through video of a 4-radiate cell of Staurastrum controversum showing strongly convergent processes each tipped with some four stout spines.