The genus Thelonectria (Nectriaceae, Hypocreales, Ascomycota) and closely related species with cylindrocarpon-like asexual states

Abstract

The genus Thelonectria and closely related species with cylindrocarpon-like asexual states are a group of perithecial ascomycetes in the family Nectriaceae that occur as saprobes and in few cases as pathogens of hardwood trees, shrubs or other plants. Although a key component of forest ecosystems around the world, species relationships and distributions of these fungi are largely unknown. The objectives of this study were to: 1) infer species rank phylogenetic relationships of the genus Thelonectria and closely related species with cylindrocarpon-like asexual states and test the monophyly of each of the groups studied; 2) delimit taxa establishing taxon circumscriptions; 3) resolve nomenclatural issues by identifying redundantly used names and synonyms; and 4) provide an updated outline to the genus, geographical distributions data and identification tools, specifically diagnostic keys and molecular data that can be used as molecular barcodes. The recovered consensus phylogeny resulted in a narrow circumscription of the genus Thelonectria, based on the type T. discophora, excluding one of the common species T. jungneri. According to the phylogenetic analyses, T. jungneri belongs in a segregate clade that should be recognized as a different genus. In the genus Thelonectria, a total of four new species and three new combinations are recognized. Additionally, three new genera, closely related to Thelonectria, are described to accommodate species displaying a morphological resemblance to those of Thelonectria: Cinnamomeonectria gen. nov. with C. cinnamomea as type species, Macronectria gen. nov. with M. jungneri as type species and including four additional newly described species, and Tumenectria gen. nov. with T. laetidisca as type species.