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:

Placoderm

 

 

STAURASTRUM


Unicellular Desmid: semicells without marginal incisions or spines, but have many small processes and arms tipped with spines (2 or more arms per semicell)
 
 
   
Staurastrum anatinum  
 
   
Staurastrum arctiscon  
 
       
Staurastrum armigerum fo. furcigerum
 
 
Staurastrum asperum  
 
 
Staurastrum avicula  
 
   
Staurastrum bieneanum  
 
       
Staurastrum ?cerastes  
 
 
Staurastrum chaetoceras  
 
   
Staurastrum cingulum  
 
 
Staurastrum ?cingulum v. obesum  
 
Staurastrum ?dilatatum  
 
 
Staurastrum ?furcatum  
 
   
Staurastrum gracile  
 
   
Staurastrum ?hirsutum  
 
Staurastrum ?hirsutum v. muricatum  
 
Staurastrum inflexum  
 
 
Staurastrum johnsonii  
 
 
Staurastum longispinum  
 
     
       
Staurastrum lunatum  
 
Staurastrum manfeldtii  
 
   
  
Staurastrum ophiura  
 
 
Staurastrum planctonicum  
 
   
Staurastrum polytrichum  
 
 
Staurastrum proboscideum  
 
 
Staurastrum pseudopelagicum  
 
Staurastrum sexangulare  
 
 
Staurastrum teliferum  

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Saccoderm:      

John Kinross
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