Staurastrum cingulumImage © Ben de Nijs

Cell of Staurastrum cingulum var. obesum in frontal view. Notice long, divergent processes, and cup-shaped semicell body.

Cell dimensions (L x B): 43 x 70 µm

Image © Ben de Nijs

Same cell of St. cingulum var. obesum in apical view showing a 3-radiate configuration.

Image © Ben de Nijs

Empty cell of St. cingulum var. obesum in frontal view showing pattern of cell wall granulation.

 

 

Desmid of the month
December 2021

Staurastrum cingulum

Just like Staurastrum pingue  St. cingulum is characterized by long, divergent processes by which it is well adapted to a planktic way of life. An important morphological difference between those two species is in the shape and ornamentation of the semicell body. Whereas semicell body in St. pingue is campanulate in outline and for the main part destitute of any ornamentation, that of St. cingulum, particularly its var. obesum, is rather cup-shaped and partly furnished with acute granules. In the Netherlands, St. cingulum var. obesum is of occasional occurrence in plankton of meso-eutrophic, circumneutral water bodies.

Image © Ben de Nijs

Another cell of St. cingulum var. obesum with semicells in different stage of development.

Image © Ben de Nijs

Empty cell of St. cingulum var. obesum in vertical view showing a pronounced supraisthmial ring of granules.