homotypic synonym, validly published under the ICN (Botanical Code), illegitimate name
Porphyrosiphon stagninus Anagnostidis 2001 is illegitimate because it is a homotypic synonym of Phormidium stagninum Anagnostidis 2001, which was proposed in the same publication.Publication:
McNeill J, Barrie FR, Buck WR, Demoulin V, Greuter W, Hawksworth DL, Herendeen PS, Knapp S, Marhold K, Prado J, et al. International Code of Nomenclature for Algae, Fungi and Plants (Melbourne Code). Koeltz Scientific Books, Königstein, 2012.