Persistent hamathecial threads in the Nectriaceae, Hypocreales: Thyronectria revisited and re-instated.

Based on type studies and freshly collected material we here re-instate the genus Thyronectria (Nectriaceae, Hypocreales). Species of this genus were recently for the most part classified in the genera Pleonectria (Nectriaceae) or Mattirolia (Thyridiaceae), because Thyronectria and other genera had been identified as members of the Thyridiaceae due to the presence of paraphyses. Molecular phylogenies based on several markers (act, ITS, LSU rDNA, rpb1, rpb2, tef1, tub) revealed that the Nectriaceae contain members whose ascomata are characterised by long, more or less persistent, apical paraphyses. All of these belong to a single genus, Thyronectria, which thus has representatives with hyaline, rosy, green or even dark brown and sometimes distoseptate ascospores. The type species of Thyronectria, T. rhodochlora, syn. T. patavina, syn. T. pyrrhochlora is re-described and illustrated. Within the Nectriaceae persistent, apical paraphyses are common in Thyronectria and rarely also occur in Nectria. The genus Mattirolia is revised and merged with Thyronectria and also Thyronectroidea is regarded as a synonym of Thyronectria. The three new species T. asturiensis, T. caudata and T. obscura are added to the genus. Species recently described in Pleonectria as well as some species of Mattirolia are combined in the genus, and a key to Thyronectria is provided. Five species are epitypified. The type species of the genus Thyridium (Thyridiaceae), T. vestitum, is included in phylogenetic analyses to illustrate the phylogenetic distance of Thyronectria from the Thyridiaceae.