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 dorsoventrally flattened without lateral incisions, with marginal spines and a central process.
|Xanthidium antilopaeum v. depauperatum|
|Xanthidium antilopaeum v. hebridarum|
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