Image © Marien van Westen

Cell of Staurastrum echinatum in frontal view. Notice widely open sinus and closely set, partly furcate, thorn-like spines.

Cell dimensions (L x B, including spines): 36 x 33 µm

 


Desmid of the month
December 2014

Staurastrum echinatum

St. echinatum is a spiny desmid that may be confused with a number of other  Staurastrum species. Characteristic features are the widely open sinus and the closely set, rather short, thorn-like spines. Often, part of the spines are furcate and usually the downwardly projected spine at the basal semicell angles is larger than those elsewhere on the semicell surface. Zygospores are irregularly globose and furnished with short, stout spines which are two- or threefold furcate. St. echinatum is characteristic of acidic, oligotrophic (but slightly minerotrophic) bog pools. In the Dutch province of Drenthe it is of occasional occurrence, elsewhere in the Netherlands it is very rare. Zygospores were only very recently described for the first time (Van Westen & Coesel 2014).

Image © Marien van Westen

Empty cell of Staurastrum echinatum in rear view. Notice extra large, convergent spines at the basal angles.

 

 

Staurastrum echinatum in top-aanzichtMouse over images © Marien van Westen

Empty semicell of Staurastrum echinatum in apical view. Notice series of furcate spines (in top view).


 

Image © Marien van Westen

Zygospore of Staurastrum echinatum. Notice big, 2-3-fold furcate spines.

 

Reference:

Van Westen, W. & Coesel, P.F.M., 2014. Taxonomic notes on Dutch desmids VI (Streptophyta, Desmidiales): new species, newly described zygospores. — Phytotaxa 166: 285-292.