First record of Oldenlandia corymbosa (Spermacoceae-Rubiaceae), a new alien species for Paraguay and Argentina

Background and aims: During the revision of the southern South American species of Oldenlandia, populations of O. corymbosa were found in Paraguay and Argentina. The aim of this contribution is to report the presence of this adventitious species to the Paraguayan and Argentinian flora for the first time. M&M: Living plants and herbarium material, as well as the original description of Oldenlandia corymbosa were analysed. Taxonomic and morphological analyses were performed. Collected materials were deposited in the FCQ and CTES. Results: A description of the morphology of the species and habitat based on herbarium specimens and field observations are provided, along with an illustration, photographs, and a map indicating the geographical position of the recorded populations in the Northeast and South Paraguay and Northeast Argentina in the Corrientes province. Complementary, an identification key of Oldenlandia species occurring in Argentina and Paraguay is provided. Conclusion: With the record of Oldenlandia corymbosa in Paraguay and Argentina, the range of distribution of this non-native species is extended up to the Southern Cone of South America. Its naturalized status in Paraguay raises the possibility that it was, until now, overlooked in other regions of the Northeast Argentina.