Solving the taxonomic identity of Pseudotomentella tristis s.l. (Thelephorales, Basidiomycota) – a multi-gene phylogeny and taxonomic review, integrating ecological and geographical data

Abstract

P.tristis is an ectomycorrhizal, corticioid fungus whose name is frequently assigned to collections of basidiomata as well as root tip and soil samples from a wide range of habitats and hosts across the northern hemisphere. Despite this, its identity is unclear; eight heterotypic taxa have in major reviews of the species been considered synonymous with or morphologically similar to P.tristis, but no sequence data from type specimens have been available. With the aim to clarify the taxonomy, systematics, morphology, ecology and geographical distribution of P.tristis and its morphologically similar species, we studied their type specimens as well as 147 basidiomata collections of mostly North European material. We used gene trees generated in BEAST 2 and PhyML and species trees estimated in STACEY and ASTRAL to delimit species based on the ITS, LSU, Tef1α and mtSSU regions. We enriched our sampling with environmental ITS sequences from the UNITE database. We found the P.tristis group to contain 13 molecularly and morphologically distinct species. Three of these, P.tristis, P.umbrina and P.atrofusca, are already known to science, while ten species are here described as new: P.sciastrasp. nov., P.tristoidessp. nov., P.umbrinascenssp. nov., P.pinophilasp. nov., P.alnophilasp. nov., P.alobatasp. nov., P.plurilobasp. nov., P.abundilobasp. nov., P.rotundisporasp. nov. and P.mediasp. nov. We discovered P.rhizopunctata and P.atrofusca to form a sister clade to all other species in P.tristis s.l. These two species, unlike all other species in the P.tristis complex, are dimitic. In this study, we designate epitypes for P.tristis, P.umbrina and Hypochnopsisfuscata and lectotypes for Auriculariaphylacteris and Thelephorabiennis. We show that the holotype of Hypochnussitnensis and the lectotype of Hypochnopsisfuscata are conspecific with P.tristis, but in the absence of molecular information we regard Pseudotomentellalongisterigmata and Hypochnusrhacodium as doubtful taxa due to their aberrant morphology. We confirm A.phylacteris, Tomentellabiennis and Septobasidiumarachnoideum as excluded taxa, since their morphology clearly show that they belong to other genera. A key to the species of the P.tristis group is provided. We found P.umbrina to be a common species with a wide, Holarctic distribution, forming ectomycorrhiza with a large number of host species in habitats ranging from tropical forests to the Arctic tundra. The other species in the P.tristis group were found to be less common and have narrower ecological niches.

Diversity and distribution of Finnish aphyllophoroid and heterobasidioid fungi (Basidiomycota): An update

“…Notes. 5 th -12 th records in Finland; previous records: Parainen (1b), Lammi (2a), Ikaalinen (2a), and Ruovesi (2b) (Svantesson et al 2019) Distribution. New to Finland, and hence new to 1b (Fig.…”

“…Notes. 3 rd record in Finland; previous records: Lammi (2a) and Jyväskylä (2b) (Svantesson et al 2019). Note:…”

“…Pseudotomentella alobata has been reported in Sweden, Norway and Slovenia (Svantesson et al 2019). To date, data on habitat are scarce, but recent Scandinavian collections have been made in old-growth coniferous or mixed forests on soil with high pH (Svantesson et al 2019). The species is described from the Pseudotomentella tristis group.…”

Polyozellus vs. Pseudotomentella: generic delimitation with a multi-gene dataset

“…rhizopunctata ( Martini & Hentic 2003 ). Svantesson et al (2019 , 2021) described 12 new species from basidiomata previously identified as Ps. tristis , de-synonymised Ps.…”

“…This feature in combination with the texture characteristics of their basidiomata makes Pseudotomentella readily recognisable under the microscope and to the trained eye they can be identified to species group already in the field. For identification to the level of species a combination of macro- and microscopical features is often needed ( Kõljalg 1996 , Kõljalg & Larsson 1998 , Kõljalg & Dunstan 2001 , Martini & Hentic 2002 , 2003 , Svantesson et al 2019 , 2021 ).…”