Increasing the species diversity in the Aspergillus section Nidulantes: Six novel species mainly from the indoor environment

ABSTRACT

Aspergillus section Nidulantes encompasses almost 80 homothallic and anamorphic species, mostly isolated from soil, plant material, or the indoor environment. Some species are clinically relevant or produce mycotoxins. This study reevaluated the species boundaries within several clades of section Nidulantes. Five data sets were assembled, each containing presumptive new species and their closest relatives, and phylogenetic and phenotypic analyses were performed. We tested the hypotheses that the newly isolated or reexamined strains constitute separate species (splitting approach) or should be treated as part of broadly defined species (lumping approach). Four DNA sequence loci were amplified, internal transcribed spacer (ITS) and large subunit (LSU) regions of the rDNA and partial sequences of the β-tubulin (benA), calmodulin (CaM), and RNA polymerase II second largest subunit (RPB2) genes. The latter three loci were used for the phylogenetic analysis and served as input for single-locus (GMYC, bGMYC, PTP, and bPTP) and multilocus (STACEY and BP&P) species delimitation analyses. The phenotypic analysis comprised macro- and micromorphology (including scanning electron microscopy) and comparison of cardinal growth temperatures. The phylogenetic analysis supported the splitting hypothesis in all cases, and based on the combined approach, we propose six new species, four that are homothallic and two anamorphic. Four new species were isolated from the indoor environment (Jamaica, Trinidad and Tobago, USA), one originated from soil (Australia), and one from a kangaroo rat cheek pouch (USA).

KEYWORDS:

• Aspergillus nidulans
• Emericella
• indoor fungi
• multigene phylogeny
• multispecies coalescent model
• species delimitation
• sterigmatocystin production
• 6 new taxa

ACKNOWLEDGMENTS

We acknowledge the Imaging Methods Core Facility at BIOCEV, institution supported by the Czech-BioImaging large RI projects (LM2015062 and CZ.02.1.01/0.0/0.0/16_013/0001775, funded by the Ministry of Education, Youth and Sports of the Czech Republic), for their support with obtaining imaging data presented in this paper. We thank Milada Chudíčkova, Adéla Kovaříčková, and Petra Seifertová for their invaluable assistance in the laboratory and Miroslav Hyliš for assistance with scanning electron microscopy.

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Funding

This research was supported by the project of the Charles University Grant Agency (GAUK 1434217), the project BIOCEV (CZ.1.05/1.1.00/02.0109) provided by the Ministry of Education, Youth and Sports of the Czech Republic and ERDF, the Charles University Research Centre program no. 204069, and the Czech Science Foundation grant no. 17-20286S.