Three new homothallic species of <i>Alternaria</i> section <i>Nimbya</i> 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 <i>Alternaria</i> section <i>Nimbya</i> were identified and characterized. These new species, namely, <i>Alternaria azarbaijanica, A. caspica</i>, and <i>A. eleocharidis</i>, 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 <i>Alternaria</i>, where sexual morphs are rarely observed. Phylogenetic analyses based on five gene regions (ITS-rDNA, <i>GAPDH, TEF1, RPB2</i>, and <i>Alt a 1</i>) 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 <i>Alternaria</i> section <i>Nimbya</i>. These findings reveal previously unrecognized <i>Alternaria</i> diversity on Cyperaceae hosts and underscore the value of combining morphological observations with multilocus phylogenetic approaches to resolve taxonomic complexities in <i>Alternaria</i>.