The root-symbiotic aggregate and () are congeneric: Phylogenetic and experimental evidence.

Data mining for a phylogenetic study including the prominent ericoid mycorrhizal fungus revealed nearly identical ITS sequences of the bryophilous suggesting they are conspecific. Additional genetic markers and a broader taxonomic sampling furthermore suggested that the sexual and the asexual may be congeneric. In order to further elucidate these issues, type strains of all species traditionally treated as members of the aggregate (REA) and related taxa were subjected to phylogenetic analyses based on ITS, nrLSU, mtSSU, and 2 markers to produce comparable datasets while an re-synthesis experiment was conducted to examine the root-symbiotic potential of in the . Phylogenetic evidence demonstrates that sterile root-associated , sexual and , based on , are indeed congeneric. To this monophylum also belongs the phialidic dematiaceous hyphomycetes and . We provide a taxonomic revision of the REA; and are reduced to synonymy under . , typified by , an asexual morph of which is a core member of , is also transferred to the synonymy of the latter genus. is introduced as a new root-symbiotic species from Central Europe. and are confirmed conspecific, and four new combinations in are proposed. Based on phylogenetic analyses, some sexually reproducing species can be attributed to their asexual counterparts for the first time whereas the majority is so far known only in the sexual or asexual state. sporulating is reported for the first time. Surprisingly, the mycological and mycorrhizal sides of the same coin have never been formally associated, mainly because the sexual and asexual morphs of these fungi have been studied in isolation by different research communities. Evaluating all these aspects allowed us to stabilize the taxonomy of a widespread and ecologically well-studied group of root-associated fungi and to link their various life-styles including saprobes, bryophilous fungi, root endophytes as well as fungi forming ericoid mycorrhizae and ectomycorrhizae.