The genus Gerhardtia is a saprotrophic fungal taxon in the family Lyophyllaceae, in the order Agaricales and the phylum Basidiomycota. Bon (1994) established the genus Gerhardtia based on Lyophyllum subgenus Lyophyllopsis (Gerhardt, 1982) and designated G. incarnatobrunnea (Ew. Gerhardt) Bon as the type species. The genus was initially characterized by the presence of verrucose basidiospores, basidia with siderophilous granules, a pileipellis with cutis, trichodermium, or hymeniderm organization, and an absence of clamp connections (Bon, 1994). Following the discovery of G. pseudosaponacea J.A. Cooper & P. Leonard, which has smooth basidiospores (Cooper, 2014), Vizzini, Consiglio, Setti, andErcole (2015) partly amended the genus concept as having basidiospores that are smooth or verrucose. Based on phylogenetic relationships, Vizzini et al. (2015) also clarified that G. incarnatobrunnea is synonymous with G. borealis (Fr.) Contu & A. Ortega, which was described based on specimens from Sweden. Thus, G. borealis is currently recognized as the type species of the genus. Vizzini, Angelini, and Ercole (2017) subsequently observed that the basidiospores of the genus tend to be irregular and undulate to nodulose, rather than verrucose.According to the Index Fungorum fungal database (http://www. indexfungorum.org/names/names.asp, 01 Feb 2021) and recent publications (

We performed in-vitro germination tests on seeds from five Gastrodia orchids ( G. confusa , G. elata var. elata , G. elata var. pallens , G. nipponica , and G. pubilabiata ) using one Marasmiaceae and two Mycena isolates. Mycena sp. 1 promoted germination of all five Gastrodia orchids, with root and/or tuber formation observed in G. confusa , G. nipponica , and G. pubilabiata . No additional growth was observed in the other two orchids. Mycena sp. 2 induced G. confusa , G. elata var. elata , and G. nipponica germination, whereas Marasmiaceae sp. 1 induced G. nipponica and G. pubilabiata germination. Phylogenetic analyses indicated that the two Mycena isolates represent distinct lineages within the Mycenaceae . Mycena sp. 1 and Marasmiaceae sp. 1 are closely related to Mycena abramsii and Marasmiellus rhizomorphogenus , respectively. Our results imply that Mycena and marasmioid fungi play important roles in early development in Gastrodia species, and that Mycena fungi in particular may be common mycobionts of Gastrodia species. Root and/or tuber development was observed with four plant-fungus combinations, implying that these associations persist throughout the life cycle, whereas G. elata var. elata may require different associates over time. Our findings will contribute to elucidating the mycorrhizal associations of mycoheterotrophic orchids throughout their life cycle.

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.