Freshwater Algae of North America Zygnematophyceae C.Hoek, D.G.Mann & H.M. Jahns (1995), nom. inval. - conjugating green algae see Class Zygnematophyceae Round ex Guiry (2013) Zygnematales [paraphyletic] - filamentous conjugates and saccoderm desmids Pleurodiscus Lagerh. (1895) 1 Pleurodiscus purpureus (Wolle) Lagerh. 2 Pleurodiscus borinquinae Tiffany