Towards a unified paradigm for sequence-based identification of fungi

Kõljalg, Urmas et al.The nuclear ribosomal internal transcribed spacer (ITS) region is the formal fungal barcode and in most cases the marker of choice for the exploration of fungal diversity in environmental samples. Two problems are particularly acute in the pursuit of satisfactory taxonomic assignment of newly generated ITS sequences: (i) the lack of an inclusive, reliable public reference data set and (ii) the lack of means to refer to fungal species, for which no Latin name is available in a standardized stable way. Here, we report on progress in these regards through further development of the UNITE database (http://unite.ut.ee) for molecular identification of fungi. All fungal species represented by at least two ITS sequences in the international nucleotide sequence databases are now given a unique, stable name of the accession number type (e.g. Hymenoscyphus pseudoalbidus|GU586904|SH133781.05FU), and their taxonomic and ecological annotations were corrected as far as possible through a distributed, third-party annotation effort. We introduce the term ‘species hypothesis’ (SH) for the taxa discovered in clustering on different similarity thresholds (97–99%). An automatically or manually designated sequence is chosen to represent each such SH. These reference sequences are released (http://unite.ut.ee/repository.php) for use by the scientific community in, for example, local sequence similarity searches and in the QIIME pipeline. The system and the data will be updated automatically as the number of public fungal ITS sequences grows. We invite everybody in the position to improve the annotation or metadata associated with their particular fungal lineages of expertise to do so through the new Web-based sequence management system in UNITE.The North European Forest Mycologists network is acknowledged for support. Urmas Kõljalg and Kessy Abarenkov are supported by the Estonian Research Council grant no 8235.Peer reviewe

Fungi from Soomaa National Park : rarities and species new for Estonia

Peer reviewe

Solving the taxonomic identity of Pseudotomentella tristis s.l. (Thelephorales, Basidiomycota) – a multi-gene phylogeny and taxonomic review, integrating ecological and geographical data

P. tristis is an ectomycorrhizal, corticioid fungus whose name is frequently assigned to collections of basidiomata as well as root tip and soil samples from a wide range of habitats and hosts across the northern hemisphere. Despite this, its identity is unclear; eight heterotypic taxa have in major reviews of the species been considered synonymous with or morphologically similar to P. tristis, but no sequence data from type specimens have been available. With the aim to clarify the taxonomy, systematics, morphology, ecology and geographical distribution of P. tristis and its morphologically similar species, we studied their type specimens as well as 147 basidiomata collections of mostly North European material. We used gene trees generated in BEAST 2 and PhyML and species trees estimated in STACEY and ASTRAL to delimit species based on the ITS, LSU, Tef1α and mtSSU regions. We enriched our sampling with environmental ITS sequences from the UNITE database. We found the P. tristis group to contain 13 molecularly and morphologically distinct species. Three of these, P. tristis, P. umbrina and P. atrofusca, are already known to science, while ten species are here described as new: P. sciastra sp. nov., P. tristoides sp. nov., P. umbrinascens sp. nov., P. pinophila sp. nov., P. alnophila sp. nov., P. alobata sp. nov., P. pluriloba sp. nov., P. abundiloba sp. nov., P. rotundispora sp. nov. and P. media sp. nov. We discovered P. rhizopunctata and P. atrofusca to form a sister clade to all other species in P. tristis s.l. These two species, unlike all other species in the P. tristis complex, are dimitic. In this study, we designate epitypes for P. tristis, P. umbrina and Hypochnopsis fuscata and lectotypes for Auricularia phylacteris and Thelephora biennis. We show that the holotype of Hypochnus sitnensis and the lectotype of Hypochnopsis fuscata are conspecific with P. tristis, but in the absence of molecular information we regard Pseudotomentella longisterigmata and Hypochnus rhacodium as doubtful taxa due to their aberrant morphology. We confirm A. phylacteris, Tomentella biennis and Septobasidium arachnoideum as excluded taxa, since their morphology clearly show that they belong to other genera. A key to the species of the P. tristis group is provided. We found P. umbrina to be a common species with a wide, Holarctic distribution, forming ectomycorrhiza with a large number of host species in habitats ranging from tropical forests to the Arctic tundra. The other species in the P. tristis group were found to be less common and have narrower ecological niches