The phylogenetic revision of the genera Petrakia and Seifertia using LSU, ITS, RPB2 and TEF1 sequences and the re-evaluation of their morphological characteristics lead to several reclassifications: The genus Pseudodidymella as well as the genera Mycodidymella and Xenostigmina are synonymized with the genus Petrakia. Based on ITS sequence comparisons, it was previously suspected that the leaf spot pathogen Pseudodidymella fagi, which occurs on the Japanese beech Fagus crenata in Japan, is conspecific to the pathogen attacking the European beech Fagus sylvatica in Switzerland and Germany since 2008. Herein, we show that Japanese and European collections represent separate species and describe the European one as Petrakia liobae new to science. Apart from that, we make the new combinations Petrakia fagi and Petrakia minima. The names Petrakia aesculi and Petrakia aceris are validated. A 60-year-old collection from Wisconsin USA, designated as Petrakia echinata on leaves of silver maple (Acer saccharinum), proved to be another species new to science and is described here as Petrakia greenei. Consequently, there is currently no evidence of the European P. echinata to occur in North America. In contrast, P. echinata was found to infect the North American big leaf maple (Acer macrophyllum) in Europe. Antromycopsis alpina, described in 1914, was rediscovered in the Swiss Alps from dry fruits of Rhododendron ferrugineum. It is combined in Seifertia as S. alpina, based on molecular phylogenetic and morphological analyses. This anamorphic fungus appears to be native to Europe and does not cause a bud disease on Rhododendron in contrast to the closely related S. azaleae. Seifertia shangrilaensis is the third species of this genus that is closely related to Petrakia. Both genera belong to the family Melanommataceae.