RESUMO
Although Aspergillus fumigatus is the major agent of invasive aspergillosis, an increasing number of infections are caused by its cryptic species, especially A. lentulus and the A. viridinutans species complex (AVSC). Their identification is clinically relevant because of antifungal drug resistance and refractory infections. Species boundaries in the AVSC are unresolved since most species have uniform morphology and produce interspecific hybrids in vitro. Clinical and environmental strains from six continents (n = 110) were characterized by DNA sequencing of four to six loci. Biological compatibilities were tested within and between major phylogenetic clades, and ascospore morphology was characterised. Species delimitation methods based on the multispecies coalescent model (MSC) supported recognition of ten species including one new species. Four species are confirmed opportunistic pathogens; A. udagawae followed by A. felis and A. pseudoviridinutans are known from opportunistic human infections, while A. felis followed by A. udagawae and A. wyomingensis are agents of feline sino-orbital aspergillosis. Recently described human-pathogenic species A. parafelis and A. pseudofelis are synonymized with A. felis and an epitype is designated for A. udagawae. Intraspecific mating assay showed that only a few of the heterothallic species can readily generate sexual morphs in vitro. Interspecific mating assays revealed that five different species combinations were biologically compatible. Hybrid ascospores had atypical surface ornamentation and significantly different dimensions compared to parental species. This suggests that species limits in the AVSC are maintained by both pre- and post-zygotic barriers and these species display a great potential for rapid adaptation and modulation of virulence. This study highlights that a sufficient number of strains representing genetic diversity within a species is essential for meaningful species boundaries delimitation in cryptic species complexes. MSC-based delimitation methods are robust and suitable tools for evaluation of boundaries between these species.
RESUMO
During the last two decades, the unprecedented development of molecular phylogenetic tools has propelled an opportunity to revisit the fungal kingdom under an evolutionary perspective. Mycology has been profoundly changed but a sustained effort to elucidate large sections of the astonishing fungal diversity is still needed. Here we fill this gap in the case of Lyophyllaceae, a species-rich and ecologically diversified family of mushrooms. Assembly and genealogical concordance multigene phylogenetic analysis of a large dataset that includes original, vouchered material from expert field mycologists reveal the phylogenetic topology of the family, from higher (generic) to lower (species) levels. A comparative analysis of the most widely used phylogenetic markers in Fungi indicates that the nuc rDNA region encompassing the internal transcribed spacers 1 and 2, along with the 5.8S rDNA (ITS) and portions of the genes for RNA polymerase II second largest subunit (RPB2) is the most performing combination to resolve the broadest range of taxa within Lyophyllaceae. Eleven distinct evolutionary lineages are identified, that display partial overlap with traditional genera as well as with the phylogenetic framework previously proposed for the family. Eighty phylogenetic species are delineated, which shed light on a large number of morphological concepts, including rare and poorly documented ones. Probing these novel phylogenetic species to the barcoding method of species limit delineation, indicates that the latter method fully resolves Lyophyllaceae species, except in one clade. This case study provides the first comprehensive phylogenetic overview of Lyophyllaceae, a necessary step towards a taxonomical, ecological and nomenclatural revision of this family of mushrooms. It also proposes a set of methodological guidelines that may be of relevance for future taxonomic works in other groups of Fungi.
