One species and one variety of Gnomoniaceae (Diaporthales) on Alnus substrate are reported as new to Bulgaria: Apiognomonia alniella var. alniella, Gnomonia nervisequa. Alnus glutinosa is found as a new substrate of Gnomonia setacea. A key for determination of Bulgarian Gnomoniaceae is proposed.

Data about order Diaporthales, includind i ve families, 31 genera, and 104 species are included. Diaporthalean fungi are reported on 94 species of higher plants (grasses, shrubs and trees) from 46 genera, which are referred to 22 plant families. General information on seasonal development and vertical distribution of the fungi throughout the country is presented also. This book includes a general part dealing with the principles of classification,

Three species of the Gnomoniaceae, Gnomonia betulina, Hypospilina pustula, and Plagiostoma arnstadtiense, are reported as new to Romania. Gnomonia setacea is found on new substratum.