Search

Paxillus rubicundulus P.D. Orton has been shown to be a complex of at least three ectomycorrhizal taxa strictly associated with alders (Alnus) in Europe, P. rubicundulus s. str., and two undescribed clades. To assess the taxonomic status of these three clades and their phylogenetic relationships, phylogenetic analyses of two independent gene regions (ITS and gpd), combined with macro- and micromorphological comparisons of genetically identified specimens, were carried out. A total of 85 sequences were successfully obtained from basidiomata and alder mycorrhizae collected in France and Algeria and combined with GenBank and UNITE sequences. The phylogenetic results and estimates of genetic diversity confirmed that the three clades are distinct species, often found in sympatry. As a result, P. rubicundulus s. str. was redefined based on the revision of type material, and Paxillus adelphus and Paxillus olivellus are introduced as new Linnaean names. The often used name Paxillus filamentosus is rejected since it could not be applied to any of the new species. The three species are distinguished micromorphologically by spore size and shape. They are widely distributed in Europe, North Africa and western Asia; P. rubicundulus is rare, and all species have a limited host range., (Copyright © 2016 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.)

Paxillus involutus is a model species for ecological or physiological studies of ectomycorrhizal agaricomycetes. Three to six groups or species linked to it have been ecologically and morphologically distinguished. Phylogenetic studies have revealed the existence of four species in Europe: Paxillus ammoniavirescens, Paxillus obscurisporus, P. involutus, and a fourth as yet not described species. We studied 47 collections from 24 French and Italian locations, supplemented with GenBank data, in order to genetically and taxonomically delineate these species. Phylogenetic analyses of three nuclear DNA regions (rDNA internal transcribed spacer (ITS), tef1-α, and gpd) confirmed the four European species. Morphology, culture, and ecology features allowed us to delineate species boundaries and to describe the fourth species we named Paxillus cuprinus since it turns coppery with age. As there is no existing original herbarium specimen for P. involutus, one of our collections was chosen as the epitype. The low genetic diversity found in P. cuprinus correlates with stable morphological traits (basidiome colour, ovoid-amygdaliform spores with an apical constriction) and with ecological preferences (association with Betulaceae in open and temperate areas). In contrast, P. ammoniavirescens is characterized by a high genetic diversity and a high variation of its morphological and ecological features., (Copyright © 2013 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.)