Sir

I applaud the discovery by C. M. O'Gorman and colleagues of a sexual stage in the medically important fungus Aspergillus fumigatus (Nature 457, 471–474; 2009). However, I question the introduction of a new scientific name for it, Neosartorya fumigata.

Mycologists know from morphological and now molecular phylogenetic evidence that the asexual A. fumigatus belongs with species that also produce a Neosartorya sexual stage. In the molecular era, the need for a single species to have separate scientific names for its various asexual stages has become obsolete. Species with no sexual stage can be placed with those that have. Even in the 1960s, Aspergillus monographer Kenneth Raper used one name for one fungus in Aspergillus.

Mycology is unique in permitting different binomials to be applied to the various sporing stages of the same living species. The need to evolve from this archaic position to that of a single name for one species in all its sporing states was advocated by Don Reynolds and John Taylor in 1991. In 2005, the XVII International Botanical Congress established a committee to consider options for changing the pertinent rules: that committee is due to report in 2011.

O'Gorman and colleagues did not contravene the current international rules in introducing N. fumigata, but have precipitated a potential source of confusion. That name is now available to apply to all stages of this fungus, including the asexual. The scientific community faces the prospect of reference to this species, even when dealing with just the asexual stage, using only the Neosartorya name.

The pragmatic approach is to use only the name A. fumigatus, regardless of whether the sexual or the asexual stage of the fungus is being referred to. This would be in line with the practice in A. nidulans, where the available name Emericella nidulans, based on the sexual stage of that species, is largely ignored.