Morphological and molecular characterization of Curvularia species from Iran, with description of two novel species and two new records

Curvularia species exhibit a wide range of ecological roles, including plant, animal, or human pathogens, as well as epiphytes, saprophytes, or endophytes, predominantly associated with cultivated cereals. In this study, several fungal isolates with similar characteristics in the genus Curvularia were recovered from various poaceous hosts (Poales plants) in different locations in Iran during 2012‒2022. Based on the morphological characteristics and multilocus phylogeny of the translation elongation factor-1 alpha (TEF1), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and the internal transcribed spacer (ITS-rDNA) genes, the studied isolates were assigned to five species, of which Curvularia caspica, sp. nov. and C. cyperi, sp. nov. are introduced as novel species and Curvularia nodulosa and C. oryzae are new records for Iran’s mycobiota. Molecular studies revealed a closer relationship between one of the studied species (Curvularia sp.) and C. frankliniae. However, due to the absence of detailed morphological characteristics for C. frankliniae, morphological comparisons were not feasible. To precisely establish their phylogenetic position, more isolates need to be analyzed. Consequently, the studied species was identified as Curvularia sp. in this study. Additionally, a new clade, “papendorfii,” was established to accommodate 11 species that share common morphological characteristics and form a distinct clade in phylogenetic analyses. The morphology, habitat, distribution, and evolutionary relationships of each species with other Curvularia species were analyzed, accompanied by detailed illustrations and descriptions. This comprehensive study offers valuable insights into the diversity and distribution of Curvularia species, enhancing our understanding of fungal ecology and taxonomy.