One fungus – which name: What to do with Aspergilli ?

The taxonomy of fungi has been under significant discussion over the last years, in particular due to the molecular/sequence data that has become available. The outcome of these discussions also affect researchers outside the taxonomy field as it determines the names that should be used for fungal species. Recently, the proposal to revise article 59 of the botanical code was accepted at the 2011 IBC Nomenclature Section at Melbourne and the principle of "one fungus : one name" was established (Norvell et al. 2011).

These new nomenclatural rules have large implication for Aspergillus. Should we only use the Aspergillus name for all Aspergillus species (including the teleomorphs) or should we use the teleomorph names (e.g. Neosartorya, Emericella, Eurotium)? On 12-13 April 2012 a conference in Amsterdam, The Netherlands (entitled One fungus = Which name and organized by the CBS) was held, where this issue was discussed. As this conference was mainly attended by taxonomists, the outcome is of relevance for all people working on Aspergillus, we have sought also the views from the (applied) researchers in Aspergillus.

Five options were proposed

Option 1: Use both names (e.g. Aspergillus tetrazonus Samson & W. Gams [Emericella quadrilineata (E. Yuill) Malloch & Cain]. This option is not allowed according to the Amsterdam declaration and the Melbourne Code (ICN).

Option 2: Keep the name Aspergillus, and omit all others (sensu Raper & Fennell 1965). Data indicate that Aspergillus is largely monophyletic; however, the phenotypically deviating genera Polypaecilum and Phialosimplex form a strongly supported clade within this genus and should then also become Aspergillus.

Consequences and problems: Loss of information for those dealing with heat- or xerotolerant species (Neosartorya, Eurotium, etc.) and those working on the sex /mating type genes in Aspergillus. Loss of the well-known genera Eurotium, Neosartorya and Emericella.

Option 3: According to the current phylogenetic studies, Aspergillus and its related teleomorphs can be split up into several clades representing genera, such as Neosartorya, Eurotium, Emericella, Petromyces, etc. This division is possible under the presumption that all Aspergillus species can be assigned to a monophyletic genus.

Consequences and problems: The type of Aspergillus is A. glaucus and belongs to section Aspergillus. This would mean that the name Eurotium will be lost and the genus name Aspergillus would be lost for other Aspergillus sections (e.g. for the commonly occurring species such as A. niger, A. flavus and A. oryzae). This would create taxonomical instability.

Option 4: As Option 3 but propose to select another type species of Aspergillus (e.g. A. niger). In that scenario, the name Aspergillus is used for e.g. A. niger, A. flavus, A. oryzae; Emericella of E. nidulans andA. versicolor, Neosartorya for A. fumigatus and A. clavatus, and Eurotium for E. herbariorum and A. penicillioides. In this option, the phenotypically deviating genera Polypaecilum and Phialosimplex can be retained.

Consequences and problems: Aspergillus fumigatus becomes Neosartorya fumigata, Aspergillus clavatus  > Neosartorya clavata, Aspergillus penicillioides > Eurotium penicillioides etc.

Option 5: Compromise: Keep the name Aspergillus (as option 2), and treat other names as optional when it has a meaning (but always together with the Aspergillus name!). For example, Neosartorya spp. for isolates recovered from canned products (ascospores are heat resistant), Eurotium sp. isolated from eg. salted fish, Emericella nidulans when expression of genes during sexual development are examined.

Result of the pol and ICPA decision: The result of the pol showed that 81% of the users like to keep the name Aspergillus (Option 2). In their meeting on April 14 2012 members of ICPA voted and Option 5 received the majority of the votes. Two members of ICPA voted for Option 4 (see minutes of the meeting). Read more >>