Closterium gracileImage © Paul Wouters

Closterium gracile. Notice slender cell shape and almost parrallel lateral margins.

Cell dimensions (L x B): 180 x 5 µm

 

 

Desmid of the month
January 2017

Closterium gracile

Cl. gracile is a slender Closterium species. Cells are straight and cylindric for most of their length, only near the ends they gradually attenuate and become slightly incurved. The apices are truncately rounded and have a distinct end-pore associated with an internal thickening of the cell wall. Zygospores are globose or broadly elliptic*. In the Netherlands, Closterium gracile is of occasional occurrence in various slightly acidic, mesotrophic habitats. Zygospores are only incidentally encountered.

* Closterium gracile var. lundellii the zygospore of which is characterized by horns extending into the empty gametangial cells is better to be considered a separate species.

Closterium gracile, var. elongatum0Closterium gracile, var. elongatum
Image © Alfred van Geest

Closterium gracile var. elongatum, characterized by a very high cell length to breadth ratio.
Cell dimensions: 400 x 3.5 µm

Closterium gracile var. elongatum at higher magnification
Image © Alfred van Geest

Cl. gracile var. elongatum. Cell at higher magnification. Notice the relatively broad apices.

 

Closterium gracile, zyeospore
Image © Bart van Tooren

Globose, smooth-walled zygospore of Closterium gracile