Molecular phylogenetic analyses of ITS-LSU rDNA sequence data demonstrate that Melanconis species occurring on Juglandaceae are phylogenetically distinct from Melanconis s.str., and therefore the new genus Juglanconis is described. Morphologically, the genus Juglanconis differs from Melanconis by light to dark brown conidia with irregular verrucae on the inner surface of the conidial wall, while in Melanconis s.str. they are smooth. Juglanconis forms a separate clade not affiliated with a described family of Diaporthales, and the family Juglanconidaceae is introduced to accommodate it.