A reappraisal of Aspergillus section Nidulantes with descriptions of two new sterigmatocystin-producing species

Aspergillus section Nidulantes is a speciose group of microscopic fungi whose species are important in indoor air quality, food spoilage, mycotoxin production and human pathogenicity. We assembled as many species from the section as possible with either type specimens or protologues for analysis. DNA sequences were obtained from up to four loci to conduct phylogenetic analysis of sect. Nidulantes and other species in subgenus Nidulantes. Comparisons of phenetic characters were made. Our goal was to recognize monophyletic taxa for section Nidulantes as well as the other taxa in the subgenus. Phylogenetic analysis indicated that sections Versicolores and Aenei formed subclades in the larger clade containing the type species of section Nidulantes. In order to maintain monophyly in section Nidulantes, we synonymized sects. Versicolores and Aenei with sect. Nidulantes. In place of sections, we have identified six subclades in sect. Nidulantes that also have shared phenetic character sets that allow for easier morphological identification of species. Earlier reports showed that standard beta-tubulin primers can occasionally amplify the tubC gene rather than the benA gene they were designed for. We show that codon usage analysis can easily distinguish between these paralogues, and we provide primer pair options to allow benA amplifications. Two new sect. Nidulantes species are described from European caves, A. croceus (Spain) and A. askiburgiensis (Czech Republic). The analysis of exometabolites showed that both species are able to produce the mycotoxin sterigmatocystin and some additional compounds.