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, forming a flat plate: semicells are divided by several deep incisions.
Micrasterias americana  
Micrasterias crux-melitensis  
Micrasterias fimbriata
Micrasterias jenneri  
Micrasterias papillifera  
Micrasterias pinnatifida  
Micrasterias radiosa  
Micrasterias rotata  
Micrasterias thomasiana v. notata  
Micrasterias truncata  

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John Kinross
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