Redelimitation of Heteroradulum (Auriculariales, Basidiomycota) with H. australiense sp. nov.

Abstract

Auriculariales accommodates species with diverse basidiomes and hymenophores. From morphological and phylogenetic perspectives, we perform a taxonomic study on Heteroradulum, a recently validated genus within the Auriculariales. The genus Grammatus is merged into Heteroradulum, and thus its generic type G. labyrinthinus is combined with Heteroradulum and G. semis is reaccepted as a member of Heteroradulum. Heteroradulum australiense is newly described on the basis of three Australian specimens. Heteroradulum yunnanense is excluded from this genus and its taxonomic position at the generic level is considered uncertain. Accordingly, the circumscription of Heteroradulum is re-delimited and the concept of this genus is adjusted by including irpicoid to poroid hymenophores and a hyphal system with clamp connections or simple septa. A key to all nine accepted species of Heteroradulum is presented.

Alloexidiopsis gen. nov., A Revision of Generic Delimitation in Auriculariales (Basidiomycota)

“…In this study, we further revise the generic delimitation of corticioid fungi in Auriculariales based on previous studies (Malysheva and Spirin, 2017 ; Li et al, 2022b ). A new genus Alloexidiopsis is erected for two new species, namely, A. australiensis and A. schistacea , a new combination from Exidiopsis as A. calcea and two new combinations from Heteroradulum as A. nivea and A. yunnanensis .…”

“…Notes: Alloexidiopsis yunnanensis was originally described in Yunnan, China as a member of Heteroradulum (Guan et al, 2020 ). However, the generic placement of this species is inaccurate as indicated in a study by Li et al ( 2022b ), who, thus, excluded it from Heteroradulum and left its generic position open. The current phylogeny recovers this species in the newly erected genus Alloexidiopsis ( Figure 1 ), so we formally propose the taxonomic transfer here.…”

“…The current dataset for phylogenetic analysis included all the main lineages in Auriculariales as ingroup taxa, while Sistotrema brinkmannii was selected as an outgroup taxon following a study by Li et al ( 2022b ). The ITS and nLSU regions were separately aligned using MAFFT version 7.110 (Katoh and Standley, 2013 ) with the G-INS-i strategy (Katoh et al, 2005 ), and then the two resulting alignments were concatenated as a single alignment.…”

“…After the erection of some new genera, e.g., Adustochaete, Amphistereum, Crystallodon, Proterochaete , and Sclerotrema and reinstatement of several previously known genera, e.g., Hirneolina, Heteroradulum , and Tremellochaete (Malysheva and Spirin, 2017 ), Eichleriella is accepted to be a monophyletic genus, while Exidiopsis and Heterochaete seem to be synonymous with a priority of the latter genus (Malysheva and Spirin, 2017 ; Alvarenga et al, 2019 ; Alvarenga and Gibertoni, 2021 ). However, certain species of Exidiopsis , even sequenced ones such as E. calcea and E. grisea , still have no appropriate placement at the generic level (Malysheva and Spirin, 2017 ; Li et al, 2022b ). In addition, the generic placement of certain recently described species of Heteroradulum is questionable as indicated in a study by Li et al ( 2022b ) and our understanding of the phylogenies in Guan et al ( 2020 ) and Li et al ( 2022a ).…”

“…However, certain species of Exidiopsis , even sequenced ones such as E. calcea and E. grisea , still have no appropriate placement at the generic level (Malysheva and Spirin, 2017 ; Li et al, 2022b ). In addition, the generic placement of certain recently described species of Heteroradulum is questionable as indicated in a study by Li et al ( 2022b ) and our understanding of the phylogenies in Guan et al ( 2020 ) and Li et al ( 2022a ). This phenomenon indicates the generic delimitation in Auriculariales that should be further clarified.…”