A new species, Gibberella gaditjirrii, which was isolated from Heteropogon triticeus and other grasses from the tropical region of northern Australia, is described. It was differentiated from morphologically similar species that form microconidia in chains by morphological characters, sexual compatibility, Amplified Fragment Length Polymorphism (AFLP) fingerprint profiles and phylogenetic clustering based on β-tubulin, elongation factor 1-α and calmodulin gene sequences. The new species is heterothallic and abundant perithecia are formed in compatible crosses. Although female fertility is low we have isolated two reliable female fertile strains. The anamorph Fusarium gaditjirrii forms chlamydospores on synthetic nutrient-poor agar (SNA) and carnation leaf agar (CLA) media in the dark in fresh wild-type cultures, a feature that helps distinguish this species morphologically from other similar species which form microconidia in chains
