The type species of the genus Gnomonia, G. gnomon, and the closely related G. setacea

Species of the diaporthalean genus Gnomonia are common yet inconspicuous and poorly known microfungi occurring mostly on overwintered leaves of trees and shrubs in the temperate zone of the northern hemisphere. Confusion exists about the type species of Gnomonia because a type was not designated. Three specific names have been mentioned in the literature as the type species: G. gnomon, G. vulgaris and G. setacea. Gnomonia gnomon was designated as the lectotype species; however, some authors have considered all three taxa to be synonymous with G. setacea having priority. Gnomonia vulgaris is a nomenclatural synonym of G. gnomon. Observations of type specimens and fresh material of G. gnomon and G. setacea reveal that these two species are distinct and can be distinguished by the position of perithecia in the leaf tissue and ascospore morphology. Descriptions and illustrations of G. gnomon and G. setacea are provided. A lectotype specimen and an epitype specimen with ex-type culture for G. gnomon are designated; an epitype for G. setacea is designated. The distinction between G. gnomon and G. setacea is supported by ribosomal DNA sequence analysis.