Mesotaeniaceae

The Mesotaeniaceae are a small family of unicellular green algae known as the "saccoderm desmids". The Mesotaeniaceae appear to be sister or ancestral to the Zygnemataceae. The desmids are a deep branching group of Zygnemataceae. Spirotaenia was found to be a basal green alga.

Genera
The Mesotaeniaceae includes the following genera:

Synonyms:
 * Ancylonema Berggren, 1872
 * Cylindrocystis Meneghini ex De Bary, 1858
 * Geniculus Prescott, 1967
 * Mesotaenium Nägeli, 1849
 * Netrium (Nägeli) Itzigsohn & Rothe, 1856
 * Nucleotaenium Gontcharov & Melkonian, 2010
 * Planotaenium (Ohtani) Petlovany & Palamar-Mordvintseva, 2009
 * Roya West & G.S.West, 1896
 * Tortitaenia A.J.Brook, 1998
 * Endospira Brébisson, nom. inval., is a synonym of Spirotaenia
 * Entospira Kuntze, 1898 is a synonym of Spirotaenia
 * Polytaenia A.J.Brook, 1997, nom. illeg., is a synonym of Tortitaenia