Perspectives into the value of genera, families and orders in classification

This paper briefly discusses the history of fungal taxonomy and contributes to the concepts and the importance of ranking genera, families and orders. We propose recommendations for introducing species into appropriate ranks such as genera, families and orders, as well as the rationale to maintain species in one genus or segregate one genus into several genera. Various ways to rank fungi have commonly been based on morphological and phylogenetic species concepts. More recently, the use of molecular clocks, coupled with estimates of divergence times, has provided insights into how to assign species and support their establishment at different taxonomic hierarchical levels. Case studies are given from the order Botryosphaeriales and Pleosporales, and the genera Camarosporium, Colletotrichum, Diaporthe, Pestalotiopsis, Lophiostoma and Agaricus to demonstrate taxonomic ambiguities and the subjectivity in classification of fungi.