Abstract
Stemphylium amaranthi was originally described from the leaves of Amaranthus retroflexous in China based only on asexual morphological characteristics. New collections of S. amaranthi from wheat and barley plants with symptoms of black (sooty) head mould in Golestan and Qazvin Provinces, Iran, revealed abundant formation of a sexual morph. The morphological identification was confirmed by sequences obtained from ITS-rDNA and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genomic loci. New information on the sexual morph of S. amaranthi is provided and the species circumscription is emended. Wheat and barley are reported as new substrates for S. amaranthi, and this species is recorded for the first time in Iran.