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.

	STAURODESMUS	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