Rediscovery of Ruellia reitzii (Acanthaceae), a narrowly endemic critically endangered species from Santa Catarina, southern Brazil, and notes on R. squarrosa

ABSTRACT Ruellia reitzii was first collected in 1948 by the prominent botanist Raulino Reitz in Santa Catarina state, southern Brazil, and the species was only known from two gatherings. Because its most recent collection was in 1953, the species was considered possibly extinct. In this work we present the rediscovery of this species, 65 years after its last collection. Here we complement and rectify the morphologic knowledge of the species, present the first photographs of living specimens and assess its conservation status. We also present notes on the authorship of the name R. squarrosa, and provide an identification key to the species of Ruellia that occur in Santa Catarina.