Abstract
The genus Melanconis (Melanconidaceae, Diaporthales) in the strict sense is here re-evaluated regarding phylogenetic structure, taxonomy, distribution and ecology. Using a matrix of sequences from ITS, LSU, ms204, rpb2, tef1 and tub2, eight species are recognised and their phylogenetic positions are determined. Based on phylogenetic, morphological and geographical differentiation, Melanconis marginalis is subdivided into four subspecies. Melanconis italica is reduced to a subspecies of Melanconis marginalis. The two species Melanconis larissae from Betula sp. and M. pacifica from Alnus rubra are described as new. Melanconis alni and M. stilbostoma are lectotypified and M. alni, M. marginalis and M. stilbostoma are epitypified. All GenBank sequences deposited as Melanconis alni are shown to actually represent M. marginalis and those as M. marginalis belong to the newly described M. pacifica. Currently, Alnus and Betula are the sole host genera of Melanconis. All species and subspecies are (re-)described and illustrated. In addition, the neotypification of Melanconium pterocaryae is here validated.