Class Conjugatophyceae Engl. (1892) see Class Zygnematophyceae Round ex Guiry (2013)
   Order Zygnematales - filamentous conjugates and saccoderm desmids
     Family Zygnemataceae (Meneghini) Kützing (1843)
       Genus Zygnema C.Agardh (1817), nom. cons.
         Zygnema purpureum Wolle see Pleurodiscus purpureus (Wolle) Lagerh.