Class Cyanoprokaryota Komárek & Golubić 1990 nom. nud. - cyanoprokaryotes Subclass Nostocophycidae Hoffmann, Komárek & Kaštovský (2005), nom. inval. [monotypic] Order Nostocales Borzì (1914) see Order Nostocales corrig. Borzì 1914 Family Microchaetaceae Lemmermann (1907) see Family Rivulariaceae Frank (1886) Genus Petalonema Berkeley ex Correns (1889) see Genus Petalonema Berkeley ex Correns 1889