Class Conjugatophyceae Engl. (1892) see Class Zygnematophyceae Round ex Guiry (2013) Order Desmidiales - placoderm desmids 1 Family Closteriaceae A. Pritch. (1872) 2 Family Desmidiaceae Kützing ex Ralfs (1845) 3 Family Gonatozygaceae 4 Family Peniaceae Haeckel (1894) [monotypic]