Morphology: still essential in a molecular world

Morphological characters have long served as the basis for mycological taxonomy. But with the advent of DNA sequence data, is morphology still useful? Will barcoding replace visual identification? Taxa in the Dothideomycetes serve to illustrate how molecular analyses have revised species relationships and higher-level systematics. Aspergillus species are now defined using a polyphasic approach with morphology assuming a lesser role. Sequence analyses likewise reveal that Colletotrichum species complexes once considered good morphological species now comprise many phylogenetically distinct species. Although Phyllosticta species concepts are less advanced, sequence data are expected to reveal new species in that genus as well. Molecularly supported higher taxa in Dothideomycetes often differ from those circumscribed by morphological characters. However, DNA barcodes, recently applauded as a magic formula for species identification, are yet to be determined for many genera, and too many GenBank sequences are wrongly named or contain sequencing errors. Thus, despite recent molecular advances, there is an unprecedented need for mycologists to return to the field, recollect species, and re-typify taxa with living cultures. Only after we obtain sequences from species and genera linked to properly named taxa will barcoding become successful.