The impact of molecular characters on systematics of filamentous ascomycetes.

Information derived from nucleic acid analyses either has complemented phylogenetic arguments based on phenetic characters or facilitated choice among competing hypotheses. Despite limited taxon sampling, a picture of the interrelationships of filamentous Ascomyceteas at higher taxonomic levels is developing. Intergeneric relationships within groups that include economically important fungi (e.g. Eurotiales, Hypocreales) are being clarified, and generic circumscriptions redefined. Molecular analyses have supported predictions of links between individual asexual species of groups or asexual species of the Fungi Imperfecti, and groups of Ascomycete genera and species. However, individual asexual species have not been linked unequivocally to individual Ascomycete species. Anamorph names are necessary and should be retained because teleomorphs may not be recognized in vivo nor formed in vitro. In the few cases where phenetic and molecular phylogenies seem irreconcilable, the ribosomal genes may not give the most parsimonious explanation. The taxon name Plectomycetes is confused and should be dropped.