A multigene analysis of a combined ITS-LSU-SSU-rpb2-tef1 sequence data matrix was applied to infer the phylogenetic position of the genus Thyridaria in the Pleosporales. The generic type of Thyridaria, T. broussonetiae (syn. T. incrustans), is situated in a clade currently named Roussoellaceae, which becomes a synonym of Thyridariaceae. However, Thyridaria rubronotata does not belong to this clade, but is here recognised as Cyclothyriella rubronotata in its own family Cyclothyriellaceae. The Thyridariaceae contain the genera Thyridaria, Roussoella, Roussoellopsis, Neoroussoella and the new genus Parathyridaria. Roussoella acaciae is combined in Thyridaria and Roussoella percutaenea in Parathyridaria. Ohleria modesta and an additional new thyridaria-like genus, Hobus, are found to represent isolated lineages with unresolved phylogenetic affinites within the Pleosporales. For Ohleria the new family Ohleriaceae is established. Melanomma fuscidulum belongs to Nigrograna, and three new species are described in this genus. A strain named Biatriospora marina clusters with Nigrograna. Based on the newly recognised species in Nigrograna, morphology and ecology do in no way correlate among these genera, therefore we erect the new family Nigrogranaceae for Nigrograna and recommend to discontinue the use of the family name Biatriosporaceae until fresh material of B. marina becomes available for sequencing.