Abstract
The recent molecular investigations by Kool et al. (2007) clearly showed the polyphyly of the genus Polycarpon Linnaeus (1759: 859, 881) which includes, in the new restricted sense, only the taxa belonging to the Polycarpon tetraphyllum clade, while the South American P. suffruticosum Grisebach (1874: 77−78), and P. coquimbense Gereau & Marticonema (1995: 154), and the widespread tropical P. prostratum (Forsskål 1775: 207) Ascherson & Schweinfurth (1889: 128) are to be excluded. Kool et al. (2007) also suggested treating all the members of the P. tetraphyllum group as a single species with the recognition of several subspecies. Accordingly, Iamonico (2013), and Iamonico & Domina (2015) proposed four new nomenclatural combinations [a further proposal about the northwestern American P. depressum Nuttal ex Torrey & Gray (1838: 174) is in preparation].