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.



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Saccoderm: Closteriinae

unicellular Desmid, varying from crescent shaped to straight:
radius of curvature, dimensions and wall ornamentation distinguish species
Closterium ?abruptum
Closterium acerosum

Closterium aciculare

Closterium angustatum
Closterium attenuatum
Closterium baillyanum
Closterium closterioides
Closterium cornu
Closterium costatum
Closterium dianae
Closterium dianae v. minus
Closterium dianae v. pseudodianae
Closterium directum
Closterium ehrenbergii  
Closterium gracile
Closterium gracillimum
Closterium idiosporum
Closterium incurvum
Closterium intermedium
Closterium jenneri
Closterium juncidum
?Closterium juncidum v. elongatum
Closterium kutzingii
Closterium lebleinii
Closterium littorale
Closterium lunula
Closterium moniliferum
Closterium navicula
Closterium ? parvulum
Closterium praelongum

Closterium ralfsii 
Closterium setaceum
Closterium striolatum
Closterium venus

: Gonatozygon

Filamentous Desmid: elongated cells usually in pairs joined end-to-end, ends slightly swollen, cell surface decorated, chloroplast axile.

Gonatozygon kinahanii
Gonatozygon monotaenium

: Penium

Unicellular Placoderm Desmid: cylindrical with rounded ends, cell wall granular, 1 chloroplast in each semicell (sometimes interrupted in P. margaritaceum).
Penium exiguum
Penium margaritaceum


John Kinross
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