A survey of<i>Penicillium brevicompactum</i>and<i>P. bialowiezense</i>from indoor environments, with commentary on the taxonomy of the<i>P. brevicompactum</i>groupThis paper is one of a selection of papers published in the Special Issue on Systematics Research.

We investigated the diversity of the Penicillium brevicompactum Dierckx group in dust from 54 houses in Wallaceburg, Ontario, Canada. Two taxa were predominant, P. brevicompactum and Pencillium bialowiezense Zaleski, accounting for 88.6% and 5.4% of the sample set, respectively. We further characterized multilocus haplotypes of isolates by characterizing three polymorphic genetic loci, β-tubulin (benA), histone 4 (his4A), and the internal transcribed spacer regions of ribosomal DNA (nucITS) amplified by PCR amplification and screened using heteroduplex mobility assay (HMA). Eight unique haplotypes were observed in P. brevicompactum s. str., and two in P. bialowiezense, both with a distribution characteristic of a predominantly clonal reproduction mode. Phylogenetic analysis of the β-tubulin and nucITS loci were carried out for members of the P. brevicompactum group, including ex-type material, that revealed three well-supported lineages corresponding to P. brevicompactum, P. bialowiezense (=Penicillium biourgeianum Zaleski), and Penicillium neocrassum R. Serra &amp; S.W. Peterson. The mycophilic nature of many isolates of P. bialowiezense, and some isolates of P. brevicompactum, suggests that observation of members of the P. brevicompactum group in indoor environments may predict extensive and longterm fungal colonization. We also address some nomenclatural problems in the group and epitypify P. bialowiezense.