A new species, Cortinarius prodigiosus, is reported from the Czech Republic and Hungary. This medium-sized Phlegmacium is distinguished by a yellow pileus and lower part of stipe, by greyish-violet lamellae, and by strikingly bicolorous flesh: yellow in most parts of stipe and whitish in pileus. On the basis of its morphological and molecular characters (ITS rDNA and LSU D1/D2 domain), this novel taxon can be assigned to the Splendentes group of the section Calochroi; it occurs in thermophilous oak forests on calcareous bedrock.