Typification of the name Gymnocalycium valnicekianum var. bicolor including historical and taxonomic notes and a new combination

The paper provides a typification of the name Gymnocalycium valnicekianum var. bicolor. Typification of this name was necessary most of all because the name had not been correctly typified and the holotype has not been found in the BA herbarium. A picture from Till & Amerhauser (2002) is selected as a lectotype. Due to circumstances of ambiguity around the selection of a holotype, an epitype from the locality of Cruz del Eje is designated here. The paper includes a more precise description of G. valnicekianum var. bicolor based on an analysis of three natural populations, and a new combination of the epithet bicolor at the rank of subspecies of G. mostii is published. Historical facts and assumptions about this taxon are discussed.