Abstract
The name Quercus protoroburoides is validated. It was assigned to a new science representative of the genus Quercus discovered in 1968 by Dipl. Eng. B. Buzov in the valley of river Rilska on the territory of the Rila Mountains, Bulgaria. the taxon was originally named Quercus macranthera subsp. balcanica and subsequently renamed to Quercus protoroburoides. However, it has never been described according to the International Code of Nomenclature for algae, fungi, and plants and, owing to this, the name is invalid and has never been included in any Flora or Key. It differs significantly from the already known members of this genus in Bulgaria and Europe. Information on this taxon will fill a gap in the knowledge of the taxonomic diversity in Quercus.