Towards the global phylogeny of the ectomycorrhizal genus Cortinarius (Basidiomycetes, Agaricales)
Final Report Abstract
Members of the genus Cortinarius are some of the most conspicuous ectomycorrhizal elements of nearly all forest ecosystems, where the extraradical fungal hyphae promote uptake of poorly mobile nutrient ions that are transferred to host tree(s). However, at the start of this project, there were not sufficient data to drawn consistent conclusions conceming phylogenetic relationships and pattems of geographic distribution of Cortinarius species at a global scale. Therefore, the aims of the project were to reconstruct the worldwide phylogenetic relationships and to infer major pattems of geographic distribution within the genus Cortinarius. For this purpose, an extensive taxon sampling of adequately documented specimens was analysed by using a combination of morphological and molecular approaches. By integrating molecular phylogenetic analyses from a dataset of DI-D3 + D7-D8 + RPBl A-C domain sequences with morphological and chemical features from 88 genera of Agaricales, we addressed the phylogenetic placement of the genus Cortinarius within Agaricales. Our findings suggested a close relationship between Cortinarius and the genera Crucibulum, Cyathus, Cystoderma and Phaeolepiota, which is partly in agreemeni wilh the presence of similarly shared pigments. Within the genus Cortinarius, at least eight major lineages were identified by integrating 262 ITS + 5.8S + D1 /D2 sequences wilh morphological, macrochemical and ecological data. The major lineages, "clades", found, are as follows: i) phlegmaciod species clustered into Alluti, Amarescentes, Arguti, Calochroi, Caerulescentes, Percomes, Phlegmacioides, Phlegmacium, Purpurascens, Scauri, and Vulpini clades; ii) species of the subgenera Cystogenes and Leprocybe were included in the Heterocliti; iii) most of members ofthe subgenus Myxacium were included in the Delibuti and Myxacium clades; iv) part of the Rozites were included in the Rozites clade; v) dermocyboid species are distributed into Dermocybe and Splendidi; vi) part of Sericeocybe are included in the Anomali and Telamonia clades; vii) representatives of the subgenus Cortinarius are assigned to the Cortinarius clade; viii) Telamonia species are included in the Obtusi, Renidentes and Telamonia clades. Combinations of characters such as pileipellis structure, spore morphology, stipe shape and basidiome pigmenls circumscribed these lineages. Several species within major lineages have relatively broad latitudinal distributions and others show limited distributional paltems, probably due to specific climatic and edaphic factors or very specialized host requirements. For example, the lineage Arguti lypically comprises thermophilous-xerophilous species restricted mainly to southem Europe; members of the Calochroi lineage are more common on calcareous soils across boreo-nemoral areas; many species of Phlegmacioides lineage have a limited and often northem distribution, growing on on meagre and calcareous soils; and C. subtortus and various species ofthe Scauri lineage are highly specialised to moist, acid, more or less poor and Sphagnum-rich soils. Because all Cortinarius species are obligate symbionts, the presence of appropriate plant hosts plays a cmcial role in their geographical distribution. Following the natural distribution ofthe genus Quercus, we described ten new Cortinarius species from Costa Rican neotropical montane forest. The taxonomic placement of the species was based on bolh morphological features and 29 ITS + 5.8S + D1/D2 rDNA sequences from the holotypes and also from collected samples showing some degree of intraspecific variation in morphology and/or ecology. Finally, we inferred intra- and interspecific phylogenetic relationships as well as major evolutionary Irends using 230 ITS + 5.8S + D1/D2 sequences and a subset of 60 ITS+ 5.8S +D1/D2 + RPBl sequences within the section Calochroi. More than 100 species were recognised and distributed into al least seven well-supported lineages: Calochroi, Caroviolacei, Dibaphi, Elegantiores, Napi, Pseudoglaucopodes and Splendentes. Major groupings were partly in agreement wilh earlier morphology-based, pigment relationship and phylogenetic hypotheses, whereas some relationships gave results that were unexpecied, given the phenotypicai traits. Major evolutionary trends within section Calochroi are hypothesised as follows: i) a multiple independent origin of bright basidiome pigment, and ii) the evolution of abmplly marginale to flatted stipe bulbs represents an autapomorphy. Results of this project represent considerable progress within a taxonomically complex group, and should make it much easier to either identify basidiomata and/or ectomycorrhizae, or to distinguish new species. Although several relationships and evolutionary trends are now better understood, further studies are needed to evaluate the species concepts and interpretations of phenotypicai features within lineages and regions still poorly sampled.
Publications
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2005. A framework for a phylogenetic classification in the genus Cortinarius (Basidiomycota, Agaricales) derived from morphological and molecular data. Canadian Journal of Botany 83: 1457-1477
Garnica, S, Weiß, M, Oertel B & Oberwinkler F.
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2007. New Cortinarius species associated with Quercus and Comarostaphylis in Costa Rica. Canadian Journal of Botany 85: 794-812
Ammirati J, Garnica S, Hailing RE, Mata M, Mueller GM & Carranza J
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2007. Reconstructing the evolution of agarics from nuclear gene sequences and basidiospore ultrastructure. Mycological Research 111: 1019-1029.
Garnica S, Weiß M, Walther G & Oberwinkler F
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2009. Highlyaccessed Phylogenetic relationships in Cortinarius, section Calochroi, inferred from nuclear DNA sequences. BMC Evolutionary Biology 9: 1
Garnica S, Weiß M, Oertel B, Ammirati J & Oberwinkler F
