Contributions to the family Thyridiaceae. New data on Sphaeria mutabilis

Type specimens of the genera Balzania, Mattirolia, Thyridium, and Thyronectroidea were studied. We accept Mattirolia (five species) and Thyridium (four species) in the Thyridiaceae and regard Balzania and Thyronectroidea as synonyms of Mattirolia. The occurrence of Mattirolia roseovirens in Spain represents only the second collection since its original description. Four new combinations are proposed: Mattirolia mutabilis, M. ohiensis, M. platensis, and Thyridium lasiacidis. Lectotypes are designated for M. mutabilis and M. ohiensis. A key is provided to species in the Thyridiaceae.