The genus Cercospora includes many important plant pathogenic fungi associated with leaf spot diseases
on a wide range of hosts. The mainland of Iran covers various climatic regions with a great biodiversity of vascular
plants, and a correspondingly high diversity of cercosporoid fungi. However, most of the cercosporoid species found
to date have been identified on the basis of morphological characteristics and there are no cultures that support
these identifications. In this study the Consolidated Species Concept was applied to differentiate Cercospora species
collected from Iran. A total of 161 Cercospora isolates recovered from 74 host species in northern Iran were studied
by molecular phylogenetic analysis. Our results revealed a rich diversity of Cercospora species in northern Iran.
Twenty species were identified based on sequence data of five genomic loci (ITS, TEF1-α, actin, calmodulin and
histone H3), host, cultural and morphological data. Six novel species, viz. C. convolvulicola, C. conyzae-canadensis,
C. cylindracea, C. iranica, C. pseudochenopodii and C. sorghicola, are introduced. The most common taxon was
Cercospora cf. flagellaris, which remains an unresolved species complex with a wide host range. New hosts were
recorded for previously known Cercospora species, including C. apii, C. armoraciae, C. beticola, C. cf. richardiicola,
C. rumicis, Cercospora sp. G and C. zebrina.