Two new species of <i>Sistotrema</i> s.l. (<i>Cantharellales</i>) from Japan with descriptions of their ectomycorrhizae

Abstract

We describe two new species of resupinate Sistotrema sensu lato ( Cantharellales ) collected in Japan: S. flavorhizomorphae and S. chloroporum . Both species have urniform basidia with more than four sterigmata and monomitic hyphal system, oil-rich hyphae in subiculum, which is typical for this genus. Sistotrema chloroporum is characterized by poroid hymenophore partly yellowish-green, basidia 4-6-spored, medium-sized basidiospores (4.5-6.5 × 3.5-6 µm), and broadleaf forest habitat. Sistotrema flavorhizomorphae is characterized by hydnoid-irpicoid hymenophore, bright yellowish rhizomorphs, basidia 6-8-spored, small basidiospores (3-3.5 × 2.5-3 µm), and pine forest habitat. Phylogenetic trees inferred from the fungal nrDNA ITS and LSU and the rpb2 sequences supported that both species were distinct and grouped with other ectomycorrhizal Sistotrema and Hydnum species, but their generic boundary was unclear. Mycorrhizae underneath basidiomes of both species were identified and described via molecular techniques. Mycorrhizae of S. chloroporum have similar characteristics to those of other Sistotrema s.l. and Hydnum species, i.e., S. confluens and H. repandum , whereas S. flavorhizomorphae has a distinct morpho-anatomy, for example, a distinct pseudoparenchymatous mantle. Comprehensive characterizations of basidiomes and mycorrhizae improve the taxonomic analysis of mycorrhizal species of Sistotrema s.l.

Molecular phylogeny and morphology reveal a new wood-rotting fungal species, <i>Sistotrema yunnanense</i> sp. nov. from the Yunnan-Guizhou Plateau

“…( Hydnaceae , Cantharellales ), typified by S. confluens Pers., is a comparatively large genus belonging to the phylum Basidiomycota , and is morphologically characterized by resupinate or pileate-stipitate, soft basidiomes, smooth, grandinioid, hydnoid, or poroid hymenophore with various characteristic textures (pellicular, membranaceous, or ceraceous), a monomitic hyphal system with oily inclusions, urniform basidia, and smooth, thin-walled, basidiospores containing cytoplasmic oil droplets ( Eriksson, Hjortstam, & Ryvarden, 1984 ; Bernicchia & Gorjón, 2010 ). Based on the MycoBank database ( , accessed Jun 20, 2022) and the Index Fungorum ( , accessed Jun 20, 2022), the genus Sistotrema has 204 registered species and intraspecies names, however the actual number of the species is 60 ( Eriksson et al, 1984 ; Bernicchia & Gorjón, 2010 ; Sugawara et al, 2022 ).…”

“…These pioneering phylogenetic studies reveal that the genus Sistotrema is highly polyphyletic ( Nilsson, Larsson, Larsson, & Kõljalg, 2006 ; Larsson, 2007 , Hibbett et al, 2014 ), and were conducted before the advent of molecular systematics ( Kotiranta & Larsson, 2013 ; Cao, Hu, Yu, Wei, & Yuan, 2021 ; Sugawara et al, 2022 ). Kotiranta and Larsson (2013) conducted preliminary phylogenetic research on Sistotrema and proposed a new species, S. luteoviride Kotir.…”

“…and Cantharellus ( Cao et al, 2021 ). Phylogenetic trees obtained using the fungal nuc rDNA ITS and LSU and rpb2 sequences showed that Sistotrema grouped with Hydnum ; however, the generic boundary was unclear ( Sugawara et al, 2022 ).…”

“…Johri and Platygloea disciformis (Fr.) Neuhoff were selected as an outgroup for LSU analysis based on previous study ( Sugawara et al, 2022 ) ( Fig. 1 ).…”

“…The nuc rDNA LSU analysis showed that S. yunnanense belongs to Hydnaceae ( Fig. 1 ) but not to Sistotrema s.s. clade ( Sugawara et al, 2022 ), i.e., mycorrhizal lineage.…”