Abstract
BackgroundSection Calochroi is one of the most species-rich lineages in the genus Cortinarius (Agaricales, Basidiomycota) and is widely distributed across boreo-nemoral areas, with some extensions into meridional zones. Previous phylogenetic studies of Calochroi (incl. section Fulvi) have been geographically restricted; therefore, phylogenetic and biogeographic relationships within this lineage at a global scale have been largely unknown. In this study, we obtained DNA sequences from a nearly complete taxon sampling of known species from Europe, Central America and North America. We inferred intra- and interspecific phylogenetic relationships as well as major morphological evolutionary trends within section Calochroi based on 576 ITS sequences, 230 ITS + 5.8S + D1/D2 sequences, and a combined dataset of ITS + 5.8S + D1/D2 and RPB1 sequences of a representative subsampling of 58 species.ResultsMore than 100 species were identified by integrating DNA sequences with morphological, macrochemical and ecological data. Cortinarius section Calochroi was consistently resolved with high branch support into at least seven major lineages: Calochroi, Caroviolacei, Dibaphi, Elegantiores, Napi, Pseudoglaucopodes and Splendentes; whereas Rufoolivacei and Sulfurini appeared polyphyletic. A close relationship between Dibaphi, Elegantiores, Napi and Splendentes was consistently supported. Combinations of specific morphological, pigmentation and molecular characters appear useful in circumscribing clades.ConclusionOur analyses demonstrate that Calochroi is an exclusively northern hemispheric lineage, where species follow their host trees throughout their natural ranges within and across continents. Results of this study contribute substantially to defining European species in this group and will help to either identify or to name new species occurring across the northern hemisphere. Major groupings are in partial agreement with earlier morphology-based and molecular phylogenetic hypotheses, but some relationships were unexpected, based on external morphology. In such cases, their true affinities appear to have been obscured by the repeated appearance of similar features among distantly related species. Therefore, further taxonomic studies are needed to evaluate the consistency of species concepts and interpretations of morphological features in a more global context. Reconstruction of ancestral states yielded two major evolutionary trends within section Calochroi: (1) the development of bright pigments evolved independently multiple times, and (2) the evolution of abruptly marginate to flattened stipe bulbs represents an autapomorphy of the Calochroi clade.
Highlights
Section Calochroi is one of the most species-rich lineages in the genus Cortinarius (Agaricales, Basidiomycota) and is widely distributed across boreo-nemoral areas, with some extensions into meridional zones
Garnica et al [13] analysed the phylogenetic relationships of 54 European Phlegmacium species using ITS and D1/D2 sequences of the nuclear gene coding for the ribosomal large subunit and found that members of the section Calochroi are distributed into two closely related lineages that can be assigned to Calochroi and Fulvi
These analyses showed that C. inexpectatus from Europe, and C. rhodophyllus, C. chlorophanus, C. stephanopus and C. vaginatus from South America, which are currently classified in Calochroi and Fulvi, cluster outside of the section Calochroi as conceived here
Summary
Section Calochroi is one of the most species-rich lineages in the genus Cortinarius (Agaricales, Basidiomycota) and is widely distributed across boreo-nemoral areas, with some extensions into meridional zones. Frøslev et al [16] used 54 European phlegmacioid taxa and compared phylogenies resulting from RPB1, RPB2 and ITS data as single and combined data sets, and accepted three subclades named /Calochroid, /Rufoolivacei and /Fulvi These authors showed that certain morphological features, such as a pileipellis structure (pileipellis simplex), a very broad marginate bulbous stipe base and coarse, net-like basidiospore ornamentation have evolved independently several times within the genus Cortinarius. To gain a more complete understanding of intra- and interspecific patterns of distribution and phylogenetic relationships at a global scale, we have attempted to use a more extensive sampling of calochroid and fulvoid Phlegmacium species, including European, North American, Tasmanian, New Zealand, and Central and South American collections
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