Sybren de Hoog


The leading principle of modern fungal taxonomy is molecular phylogeny. The main reason is that fungi that 
take close positions in phylogenetic trees are expected to bear ecological and medical similarities. This aspect 
has stimulated a discussion on an eventual subdivision of Aspergillus in smaller entities, which should be 
more homogeneous than the large umbrella-type of classification as used today. Examples will be provided 
showing that ecological consistency cannot be reached by splitting up the genus. Extensive chemotaxonomic 
analyses have demonstrated that many species share similar and analogous secondary metabolites across the 
genus Aspergillus, indicating that a broad generic concept is better. The molecular revolution has generated 
three types of fundamental changes in taxonomy: (1) recognition of novel molecular siblings due to the fact 
molecular methods provide more detailed insight than morphology; (2) generic rearrangements because 
phenotypically similar species appeared to be phylogenetically remote; (3) abandoning pleomorphism with 
dual naming required reconsidering of choice of generic names, which were based either on anamorphs 
or on teleomorphs. Obviously the renewed methodology continues to lead to numerous taxonomic and 
nomenclatural changes. It should be realized, however, that these are not excessive, as in other areas of 
medical mycology historic changes on the basis of phenotypic characters have been much more prolific. 
Taxonomy on the basis of phylogeny alone has a number of severe drawbacks, and therefore a polyphasic 
approach is maintained in Aspergillus, combining e.g. multilocus sequencing and the use of extrolites. For 
routine fungal diagnostics the use of a single gene (rDNA ITS) has been recommended as barcode, but in 
many groups, among which is Aspergillus, this gene is insufficiently variable and secondary barcodes are 
applied. Species delimitation and the potential use of novel approaches will be discussed. 


Full conference title: 

7th Advances Against Aspergillosis