Towards a new classification of the Arthoniales (Ascomycota) based on a three-gene phylogeny focussing on the genus Opegrapha.

A multi-locus phylogenetic study of the order Arthoniales is presented here using the nuclear ribosomal large subunit (nuLSU), the second largest subunit of RNA polymerase II (RPB2) and the mitochondrial ribosomal small subunit (mtSSU). These genes were sequenced from 43 specimens or culture isolates representing 33 species from this order, 16 of which were from the second largest genus, Opegrapha. With the inclusion of sequences from GenBank, ten genera and 35 species are included in this study, representing about 18% of the genera and ca 3% of the species of this order. Our study revealed the homoplastic nature of morphological characters traditionally used to circumscribe genera within the Arthoniales, such as exciple carbonization and ascomatal structure. The genus Opegrapha appears polyphyletic, species of that genus being nested in all the major clades identified within Arthoniales. The transfer of O. atra and O. calcarea to the genus Arthonia will allow this genus and family Arthoniaceae to be recognized as monophyletic. The genus Enterographa was also found to be polyphyletic. Therefore, the following new combinations are needed: Arthonia calcarea (basionym: O. calcarea), and O. anguinella (basionym: Stigmatidium anguinellum); and the use of the names A. atra and Enterographa zonata are proposed here. The simultaneous use of a mitochondrial gene and two nuclear genes led to the detection of what seems to be a case of introgression of a mitochondrion from one species to another (mitochondrion capture; cytoplasmic gene flow) resulting from hybridization.

The Ascomycota tree of life: a phylum-wide phylogeny clarifies the origin and evolution of fundamental reproductive and ecological traits.

We present a 6-gene, 420-species maximum-likelihood phylogeny of Ascomycota, the largest phylum of Fungi. This analysis is the most taxonomically complete to date with species sampled from all 15 currently circumscribed classes. A number of superclass-level nodes that have previously evaded resolution and were unnamed in classifications of the Fungi are resolved for the first time. Based on the 6-gene phylogeny we conducted a phylogenetic informativeness analysis of all 6 genes and a series of ancestral character state reconstructions that focused on morphology of sporocarps, ascus dehiscence, and evolution of nutritional modes and ecologies. A gene-by-gene assessment of phylogenetic informativeness yielded higher levels of informativeness for protein genes (RPB1, RPB2, and TEF1) as compared with the ribosomal genes, which have been the standard bearer in fungal systematics. Our reconstruction of sporocarp characters is consistent with 2 origins for multicellular sexual reproductive structures in Ascomycota, once in the common ancestor of Pezizomycotina and once in the common ancestor of Neolectomycetes. This first report of dual origins of ascomycete sporocarps highlights the complicated nature of assessing homology of morphological traits across Fungi. Furthermore, ancestral reconstruction supports an open sporocarp with an exposed hymenium (apothecium) as the primitive morphology for Pezizomycotina with multiple derivations of the partially (perithecia) or completely enclosed (cleistothecia) sporocarps. Ascus dehiscence is most informative at the class level within Pezizomycotina with most superclass nodes reconstructed equivocally. Character-state reconstructions support a terrestrial, saprobic ecology as ancestral. In contrast to previous studies, these analyses support multiple origins of lichenization events with the loss of lichenization as less frequent and limited to terminal, closely related species.

Contributions of rpb2 and tef1 to the phylogeny of mushrooms and allies (Basidiomycota, Fungi).

A phylogeny of the fungal phylum Basidiomycota is presented based on a survey of 160 taxa and five nuclear genes. Two genes, rpb2, and tef1, are presented in detail. The rpb2 gene is more variable than tef1 and recovers well-supported clades at shallow and deep taxonomic levels. The tef1 gene recovers some deep and ordinal-level relationships but with greater branch support from nucleotides compared to amino acids. Intron placement is dynamic in tef1, often lineage-specific, and diagnostic for many clades. Introns are fewer in rpb2 and tend to be highly conserved by position. When both protein-coding loci are combined with sequences of nuclear ribosomal RNA genes, 18 inclusive clades of Basidiomycota are strongly supported by Bayesian posterior probabilities and 16 by parsimony bootstrapping. These numbers are greater than produced by single genes and combined ribosomal RNA gene regions. Combination of nrDNA with amino acid sequences, or exons with third codon positions removed, produces strong measures of support, particularly for deep internodes of Basidiomycota, which have been difficult to resolve with confidence using nrDNA data alone. This study produces strong boostrap support and significant posterior probabilities for the first time for the following monophyletic groups: (1) Ustilaginomycetes plus Hymenomycetes, (2) an inclusive cluster of hymenochaetoid, corticioid, polyporoid, Thelephorales, russuloid, athelioid, Boletales, and euagarics clades, (3) Thelephorales plus the polyporoid clade, (4) the polyporoid clade, and (5) the cantharelloid clade. Strong support is also recovered for the basal position of the Dacrymycetales in the Hymenomycetidae and paraphyly of the Exobasidiomycetidae.

A five-gene phylogeny of Pezizomycotina.

Pezizomycotina is the largest subphylum of Ascomycota and includes the vast majority of filamentous, ascoma-producing species. Here we report the results from weighted parsimony, maximum likelihood and Bayesian phylogenetic analyses of five nuclear loci (SSU rDNA, LSU rDNA, RPB1, RPB2 and EF-lalpha) from 191 taxa. Nine of the 10 Pezizomycotina classes currently recognized were represented in the sampling. These data strongly supported the monophyly of Pezizomycotina, Arthoniomycetes, Eurotiomycetes, Orbiliomycetes and Sordariomycetes. Pezizomycetes and Dothideomycetes also were resolved as monophyletic but not strongly supported by the data. Lecanoromycetes was resolved as paraphyletic in parsimony analyses but monophyletic in maximum likelihood and Bayesian analyses. Leotiomycetes was polyphyletic due to exclusion of Geoglossaceae. The two most basal classes of Pezizomycotina were Orbiliomycetes and Pezizomycetes, both of which comprise species that produce apothecial ascomata. The seven remaining classes formed a monophyletic group that corresponds to Leotiomyceta. Within Leotiomyceta, the supraclass clades of Leotiomycetes s.s. plus Sordariomycetes and Arthoniomycetes plus Dothideomycetes were resolved with moderate support.

New insights into classification and evolution of the Lecanoromycetes (Pezizomycotina, Ascomycota) from phylogenetic analyses of three ribosomal RNA- and two protein-coding genes.

The Lecanoromycetes includes most of the lichen-forming fungal species (> 13500) and is therefore one of the most diverse class of all Fungi in terms of phenotypic complexity. We report phylogenetic relationships within the Lecanoromycetes resulting from Bayesian and maximum likelihood analyses with complementary posterior probabilities and bootstrap support values based on three combined multilocus datasets using a supermatrix approach. Nine of 10 orders and 43 of 64 families currently recognized in Eriksson's classification of the Lecanoromycetes (Outline of Ascomycota--2006 Myconet 12:1-82) were represented in this sampling. Our analyses strongly support the Acarosporomycetidae and Ostropomycetidae as monophyletic, whereas the delimitation of the largest subclass, the Lecanoromycetidae, remains uncertain. Independent of future delimitation of the Lecanoromycetidae, the Rhizocarpaceae and Umbilicariaceae should be elevated to the ordinal level. This study shows that recent classifications include several nonmonophyletic taxa at different ranks that need to be recircumscribed. Our phylogenies confirm that ascus morphology cannot be applied consistently to shape the classification of lichen-forming fungi. The increasing amount of missing data associated with the progressive addition of taxa resulted in some cases in the expected loss of support, but we also observed an improvement in statistical support for many internodes. We conclude that a phylogenetic synthesis for a chosen taxonomic group should include a comprehensive assessment of phylogenetic confidence based on multiple estimates using different methods and on a progressive taxon sampling with an increasing number of taxa, even if it involves an increasing amount of missing data.