The type specimen of Opuntia cardiosperma (Cactaceae) from Paraguay, extant in the spirit collection of the Berlin-Dahlem herbarium, is illustrated. Comparison with unidentified specimens from Paraguay and northern Argentina revealed that the species is widespread but has been confused with O. paraguayensis. An amplified description of O. cardiosperma is provided. O. chakensis and O. mieckleyi are treated as new synonyms of O. cardiosperma.
Willdenowia is an international peer-reviewed journal publishing original research papers in English from the entire fields of plant, algal and fungal systematics, covering the evolution, taxonomy and nomenclature of these organisms as well as related fields such as floristics and plant geography. Three issues appear each year (in April, August and December) in an open-access online edition and a print edition. Individual papers may be published in the online edition as fast-track articles ahead of inclusion in these issues.