Closterium ralfsii
image © Alfred van Geest (after North American material)(mouse-over)

Closterium ralfsii. Notice arched cell with distinct belly (mouse-over).
Cell dimensions (L x B): 690 x 56 µm



 


Desmid of the Month
October 2025

Closterium ralfsii


Cells of Closterium ralfsii in particular its var. hybridum, should be compared with Cl. delpontei (desmid of October 2007). As compared to that latter species, cells of Cl. ralfsii are less slender and on the ventral side marked by an inflated midregion ('belly'). In the Netherlands, the nominate variety of Cl. ralfsii is only known from the beginning of the last century but var. hybridum (less squatty than var. ralfsii) is still occasionally encountered in mesotrophic moorland pools and fen hollows.

Closterium ralfsii
image © Alfred van Geest (after North American material)(mouse-over)

Closterium ralfsii, detail of cell apex. Notice striate cell wall. (mouse-over).

Closterium ralfsii
Image © Ben de Nijs

Cl. ralfsii Notice relatively slender cell shape.