The evolution of species concepts and species recognition criteria in plant pathogenic fungi

In this paper, we review historical and contemporary species concepts and species recognition criteria for plant pathogenic fungi. Previous incongruent and unstable classification based on subjective and changing criteria have led to some confusion, especially amongst plant pathologists. The goal of systematics is to provide an informative and robust framework that stands the test of time. The taxonomic histories of Cercospora, Colletotrichum, Fusarium, as well as the rust and smut fungi, are used as examples, to show how concepts and criteria used to delimit and recognize species have changed. Through these examples we compare the Genealogical Concordance Phylogenetic Species Recognition, an extension of the Phylogenetic Species Criterion, with other species recognition criteria and show that it provides a better discrimination for delimiting species. A rapidly increasing number of cryptic species are being discovered amongst plant pathogenic fungi using the Genealogical Concordance Phylogenetic Species Recognition, and it is important to determine their host range, the severity of diseases they cause and their biosecurity significance. With rapidly expanding global trade it has become imperative that we develop effective and reliable protocols to detect these previously unrecognized pathogens