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.







Unicellular Desmid: semicells have a smooth appearance, with spines marginal, or at the angles.
Staurodesmus aversus  
Staurodesmus convergens biradiate  
Staurodesmus cuspidatus  


Staurodesmus dejectus  
Staurodesmus dejectus fo. apiculatus  
Staurodesmus ? extensus  
Staurodesmus ? indentatus  
Staurodesmus mammilatus  
Staurodesmus ? megacanthus  



Staurodesmus subtriangularis  
Staurodesmus triangularis  

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John Kinross
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