DESMIDS

Phylum Chlorophyta; sub-phylum Chlorophyceae; Order Zygnematales

There are two groups of Desmids: the "Placoderm" and the "Saccoderm" Desmids.

Placoderm desmids have cells composed of two halves (semicells), often almost divided from each other by deep median incisions. The cells are symmetrical about 3 planes, and often bear elaborate ornamentation. Genera are Cosmarium, Cosmocladium, Euastrum, Micrasterias, Staurastrum, Staurodesmus, Xanthidium.

Saccoderm desmids are simple shapes, cylindrical or spindle-shaped, rarely with any median constriction. This group forms the family Mesotaeniaceae and includes the genera Cylindrocystis, Mesotaenium, Netrium, Roya, Spirotaenia, Tortitaenia, and, in the suborder Closteriinae, Closterium, Gonatozygon and Penium, and in the suborder Desmidiinae, Actinotaenium.

             
Saccoderm:

ILLUSTRATIONS:

click on an image to enlarge: use the browser back button to return to this page

Placoderm

 

EUASTRUM

 

Cell composed of 2 symmetrical semicells with relatively flat aspect in face view (apical view elliptical). Cells generally have an apical notch and are more deeply incised around the margin.  
 
Euastrum ansatum  
 
Euastrum bidentatum  
 
Euastrum crassum  
 
Euastrum denticulatum
 
 
Euastrum didelta  
 
Euastrum dubium  
 
Euastrum elegans  
 
Euastrum inerme  
 
Euastrum insulare  
 
Euastrum insigne  
 
Euastrum oblongum  
 
Euastrum pectinatum  
 
Euastrum pinnatum  
 
Euastrum verrucosum  

click on an image to enlarge: use the browser back button to return to this page

             
Saccoderm:

John Kinross
[return to desmid key]
(back to desmid key)
[CONTENTS]