On the taxonomical identity of the South American Polycarpon apurense (Caryophyllaceae) with clarification on its distribution

As part of the ongoing studies of the genus Polycarpon (Caryophyllaceae) and the preparation of its treatment for the Argentinian Flora, we here present a taxonomic note concerning the identity of the name P. apurense. A specimen preserved at P is designated as the lectotype of this name. Its identity was discussed and the synonymy with P. prostratum, recurring in the literature, was discarded on the basis of its habit and leaf shape and size. A nomenclatural change (i.e. P. tetraphyllum subsp. apurense) is proposed here on the basis of the current concept in the genus Polycarpon. Concerning the distribution of this taxon, it is excluded from Brazil and Uruguay and its presence in Peru is uncertain.