Cosmarium subexcavatum
Image © Alfred van Geest

Cosmarium subexcavatum. Notice shallow, open sinus and globose-ovate semicells.

Cell dimensions (L x B): 28 x 18 µm

 

 

Desmid of the month
July 2022

Cosmarium subexcavatum

C. subexcavatum, just like C. excavatum, is characterized by almost globose semicells. From that latter species it differs by a less deep sinus originating at an unextended isthmus. Cell wall is furnished with relatively coarse granules arranged in more less regular transversal and longitudinal series. In the Netherlands, C. subexcavatum is of incidental occurrence on wet, sandy substrates that periodically may dry out.


Image © Alfred van Geest

Cosmarium subexcavatum. Empty cell showing more or less regular series of coarse cell wall granules.


Image © Alfred van Geest

Cosmarium subexcavatum. Vertical view of empty cell showing a circular isthmus.