Biodiversity and taxonomy of the pleomorphic genus Alternaria

The genus Alternaria, alternarioid hyphomycetes, comprise a biologically, ecologically, and morphologically rich group of fungi that has suffered from taxonomic flux for many years. The taxonomy of these fungi has been predominately based on conidial characters, which includes shape, color, septation, and patterns of secondary sporulation, and to lesser extent on host association, biochemistry, and metabolites. Recent phylogenetic studies have made significant changes to the systematic taxonomy, the accurate identification of a taxon or group of taxa, within Alternaria by elevating 26 clades to the subgeneric taxonomic status of section. This paper aims to serve as an overview of the historical and contemporary taxonomic status of the alternarioid hyphomycetes with special reference to biology, morphology, and phylogenetic biodiversity. Additionally, we propose to synonymize the genus Pseudoalternaria with Alternaria and elevate this well-supported clade to the taxonomic rank of section, Pseudoalternaria sect. nov., bringing the total number of sections to 27 in order to produce a stable and accepted taxonomy for this diverse genus.