Three new homothallic species of Alternaria section Nimbya from wetland plants in Iran

During a survey of fungi associated with Cyperaceae plants in northern and northwestern Iran, three previously undescribed species belonging to Alternaria section Nimbya were identified and characterized. These new species, namely, Alternaria azarbaijanica, A. caspica, and A. eleocharidis, spp. nov. were examined using a combination of morphological traits, cultural features, and molecular data. Remarkably, all three species produced both sexual and asexual morphs under laboratory conditions, providing rare insights into reproductive modes within Alternaria, where sexual morphs are rarely observed. Phylogenetic analyses based on five gene regions (ITS-rDNA, GAPDH, TEF1, RPB2, and Alt a 1) clarified their evolutionary relationships and supported species delimitation. Phylogenetic trees constructed using maximum likelihood, maximum parsimony, and Bayesian inference consistently resolved each species as a distinct monophyletic lineage within Alternaria section Nimbya. These findings reveal previously unrecognized Alternaria diversity on Cyperaceae hosts and underscore the value of combining morphological observations with multilocus phylogenetic approaches to resolve taxonomic complexities in Alternaria.