To explore strange new worlds - The diversification in Tremella caloplacae was linked to the adaptive radiation of the Teloschistaceae.

Lichenicolous fungi are a heterogeneous group of organisms that grow exclusively on lichens, forming obligate associations with them. It has often been assumed that cospeciation has occurred between lichens and lichenicolous fungi, but this has been seldom analysed from a macroevolutionary perspective. Many lichenicolous species are rare or are rarely observed, which results in frequent and large gaps in the knowledge of the diversity of many groups. This, in turn, hampers evolutionary studies that necessarily are based on a reasonable knowledge of this diversity. Tremella caloplacae is a heterobasidiomycete growing on various hosts from the lichen-forming family Teloschistaceae, and evidence suggests that it may represent a species complex. We combine an exhaustive sampling with molecular and ecological data to study species delimitation, cophylogenetic events and temporal concordance of this association. Tremella caloplacae is here shown to include at least six distinct host-specific lineages (=putative species). Host switch is the dominant and most plausible event influencing diversification and explaining the coupled evolutionary history in this system, although cospeciation cannot be discarded. Speciation in T. caloplacae would therefore have occurred coinciding with the rapid diversification - by an adaptive radiation starting in the late Cretaceous - of their hosts. New species in T. caloplacae would have developed as a result of specialization on diversifying lichen hosts that suddenly offered abundant new ecological niches to explore or adapt to.

Contribution to the phylogeny and taxonomy of the genus Taeniolella, with a focus on lichenicolous taxa.

Taeniolella is a genus of asexual ascomycetes with saprophytic, endophytic, and lichenicolous life styles. A phylogeny of representative species is presented, with a focus on lichenicolous taxa. We obtained mtSSU and nuLSU sequence data from culture isolates of Taeniolella and from freshly collected specimens of other taxa. Taeniolella is recovered as strongly polyphyletic. The type species, Taeniolella exilis, is placed in Kirschsteiniotheliaceae within Dothideomycetes. Other saprophytic/endophytic Taeniolella species previously assigned to Sordariomycetes based on sequences were found to represent either contaminants or species that cannot be assigned to Taeniolella for morphological reasons. Lichenicolous species are restricted to Asterotexiales (Dothideomycetes) where the sequenced species of Taeniolella do not form a monophyletic group, but are related to species of Buelliella s. lat., Karschia, Labrocarpon, Melaspilea s. lat., and Stictographa. Molecular data are, however, not sufficient to reallocate the lichenicolous Taeniolella species to other genera so far. Anamorph-teleomorph relationships between these taxa and lichenicolous Taeniolella are discussed but could not be demonstrated. The type of Buelliella is placed in Asterotexiales, and the genus recovered as polyphyletic. Three new lichenicolous Taeniolella species are described, Taeniolella hawksworthiana, Taeniolella pyrenulae and Taeniolella toruloides. Taeniolella rudis is transferred to Sterigmatobotrys.

Cyphobasidium gen. nov., a new lichen-inhabiting lineage in the Cystobasidiomycetes (Pucciniomycotina, Basidiomycota, Fungi).

Pucciniomycotina is a highly diverse group of fungi, showing a remarkably wide range of lifestyles and ecologies. However, lichen-inhabiting fungi are only represented by a few species included in the genera Chionosphaera and Cystobasidium, and their phylogenetic position has never been investigated. Phylogenetic analyses using the nuclear SSU, ITS, and LSU ribosomal DNA markers reveal that the lichenicolous members of Cystobasidium (C. hypogymniicola, C. usneicola) form a monophyletic group distinct from Cystobasidium and outside the Cystobasidiales. The new genus Cyphobasidium is consequently described to accommodate these lichen-inhabiting species. Cyphobasidium is characterized by producing conspicuous galls on the host lichen thalli, by having distinctive basidia that arise from a thick-walled, cup-like structure, the probasidium, that persists after the senescence of the actual basidium (meiosporangium), and by its lichenicolous occurrence on species of Hypogymnia and Usnea. Cyphobasidium is one of the few representatives of the Cystobasidiomycetes in which the sexual stage predominates in nature, whereas most species in the group are known only from an asexual yeast phase. This is the first time the position of lichen-inhabiting taxa within the Pucciniomycotina is investigated using molecular data.

Phylogeny and character evolution in the jelly fungi (Tremellomycetes, Basidiomycota, Fungi).

The Tremellomycetes (Agaricomycotina, Basidiomycota, Fungi) are a nutritionally heterogeneous group comprising saprotrophs, animal parasites, and fungicolous species (fungal-inhabiting, including lichen-inhabiting). The relationships of many species, particularly those with a lichenicolous habit, have never been investigated by molecular methods. We present a phylogeny of the Tremellomycetes based on three nuclear DNA ribosomal markers (nSSU, 5.8S and nLSU), representing all main taxonomic groups and life forms, including lichenicolous taxa. The Cystofilobasidiales, Filobasidiales, Holtermanniales, and Tremellales (including the Trichosporonales) are recovered as monophyletic, but this is not the case for the Tremellomycetes. We suggest, however, that the Cystofilobasidiales tentatively continue to be included in the Tremellomycetes. As currently circumscribed, the Filobasidiaceae, Sirobasidiaceae, Syzygosporaceae and Tremellaceae are non-monophyletic. Cuniculitremaceae, Sirobasidiaceae and Tetragoniomycetaceae are nested within Tremellaceae. The lichenicolous species currently included within the Tremellomycetes belong in this group, distributed across the Filobasidiales and Tremellales. Lichen-inhabiting taxa do not form a monophyletic group; they are distributed in several clades and sometimes intermixed with taxa of other nutritional habits. Character state reconstruction indicates that two morphological traits claimed to characterize groups in the Tremellomycetes (the basidium habit and basidium septation) are highly homoplastic. Comparative phylogenetic methods suggest that the transitions between single and catenulate basidia in the Tremellales are consistent with a punctuational model of evolution whereas basidium septation is likely to have evolved under a graduational model in the clade comprising the Holtermanniales, Filobasidiales, and Tremellales.

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.

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.