Ectomycorrhizal Symbionts Research Articles

Tree species-specific differences in carbon allocation to ectomycorrhizal symbionts tightly relate to ectomycorrhizal fungal community composition

Host trees allocate photosynthates to ectomycorrhizal symbionts (ECMs) in exchange for soil nutrients, and the carbon allocation has profound effects on forest carbon sequestration. However, it is still a challenge to precisely quantify the amount of carbon allocated to ECMs and to identify factors affecting this allocation. Here, we estimated tree species-specific differences and the dynamics of carbon allocation to ECMs by 13CO2 labeling along seedling development, and explored mechanisms underlying these differences from the perspective of ECM fungal community across four tree species (evergreen Picea asperata and Quercus aquifolioides, deciduous Larix gmelinii and Betula albosinensis) and three development stages (early, middle and late of the growing season). Results showed that the proportion of 13C allocated to ECMs (P13CECMs) and ECM fungal community composition varied across tree species and seedling development. P13CECMs was higher in deciduous (3.3 ± 0.7%) trees than in evergreen trees (1.6 ± 0.3%), and higher at the late (5.2 ± 0.7%) than middle (1.8 ± 0.3%) and early (0.3 ± 0.1%) growing season. The relative abundance of the four ECM exploration types (contact, short-, medium- and long-distance) was 7.8–14.8%, nearly 50%, 25.2–31.2%, and nearly 10%, respectively, and varied significantly for contact and medium-distance types. The relative abundance of contact type was higher in deciduous than evergreen trees, and higher at the late than mid-growing stage, but the opposite was true for medium-distance type. Across tree species and seedling development, P13CECMs was positively correlated with the relative abundance of contact type, but negatively correlated with that of medium-distance type. The results suggest that carbon allocation to ECMs is tightly associated with ECM fungal community composition and highlight the critical role of ECM fungal community composition in carbon budges of forest ecosystem.

Concordance of multigene genealogy along with morphological evidence unveils five novel species and two new records of boletoid mushrooms (fungi) from India

Agaricales, Russulales and Boletales are dominant orders among the wild mushrooms in Basidiomycota. Boletaceae, one of the major functional elements in terrestrial ecosystem and mostly represented by ectomycorrhizal symbionts of trees in Indian Himalaya and adjoining hills, are extraordinarily diverse and represented by numerous genera and species which are unexplored or poorly known. Therefore, their hidden diversity is yet to be revealed. Extensive macrofungal exploration by the authors to different parts of Himalaya and surroundings, followed by through morphological studies and multigene molecular phylogeny lead to the discovery of five new species of wild mushrooms: Leccinellum bothii sp. nov., Phylloporus himalayanus sp. nov., Phylloporus smithii sp. nov., Porphyrellus uttarakhandae sp. nov., and Retiboletus pseudoater sp. nov. Present communication deals with morphological details coupled with illustrations and phylogenetic inferences. Besides, Leccinellum sinoaurantiacum and Xerocomus rugosellus are also reported for the first time from this country.

Four New Species and One New Record of Thelephora from China.

Species of the genus Thelephora (Thelephorales, Thelephoraceae) are ectomycorrhizal symbionts of coniferous and broad-leaved plants, and some of them are well-known edible mushrooms, making it an exceptionally important group ecologically and economically. However, the diversity of the species from China has not been fully elucidated. In this study, we conducted a phylogenetic analysis based on the internal transcribed spacer (ITS) regions, using Maximum Likelihood and Bayesian analyses, along with morphological observations of this genus. Four new species from China are proposed, viz., T. dactyliophora, T. lacunosa, T. petaloides, and T. pinnatifida. In addition, T. sikkimensis originally described from India is reported for the first time from China. Thelephora dactyliophora, T. pinnatifida, and T. sikkimensis are distributed in subtropical forests and mainly associated with plants of the families Fagaceae and Pinaceae. Thelephora lacunosa and T. petaloides are distributed in tropical to subtropical forests. Thelephora lacunosa is mainly associated with plants of the families Fagaceae and Pinaceae, while T. petaloides is mainly associated with plants of the family Fagaceae. Line drawings of microstructures, color pictures of fresh basidiomes, and detailed descriptions of these five species are provided.

Laccaria guizhouensis sp. nov. (Agaricales, Basidiomycota) from Southwest China

ABSTRACT The genus Laccaria (Hydnangiaceae, Agaricales) is an important ectomycorrhizal symbiont of a broad range of host plants. Laccaria guizhouensis was collected from a subtropical mixed forest dominated by Fagaceae in Southwest China and described based on morphological characteristics and molecular data. Laccaria guizhouensis is characterised by its medium-sized basidiocarps and strong striate or sulcatus, flesh-coloured to brown pileus, flesh-coloured to brown lamellae, 2- to 4-spored basidia, globose to obellipsoid, hyaline, moderately echinulate basidiospores, and 1–1.5 μm-long echinulate. Phylogenetic analyses based on ITS sequences (HMAS352265 and HMAS352266) indicated that L. guizhouensis represented a new species separated from all other Laccaria species.

Polypore funga and species diversity in tropical forest ecosystems of Africa, America and Asia, and a comparison with temperate and boreal regions of the Northern Hemisphere

Polypores play a crucial role in energy recycling and forest regeneration in forest ecosystems. The majority of them are wood degraders; some are forest pathogens and others are ectomycorrhizal symbionts. The basidiocarps provide food and shelter for many organisms, mostly invertebrates, but also some vertebrates, as well as food and medicine for humans. Despite extensive research on the species diversity and phylogenetic relationships of polypores in recent years, there remains a lack of comprehensive understanding of their distribution patterns and species composition at the large scale. Checklists of polypores from the tropical zone, including tropical Africa, tropical America, and tropical Asia, were analyzed for species diversity, distribution patterns, major taxa, and nutritional modes. A total of 1,902 polypore species was found in the three regions, representing 8 orders, 46 families, and 250 genera of Agaricomycetes. The orders Polyporales (especially the family Polyporaceae) and Hymenochaetales (especially the family Hymenochaetaceae) had the most prolific taxa, with their species accounting for 93.4% of the total polypores listed. Each of 1,565 (or 82.3%) of the total 1,902 species were found in only one of the three regions studied, and we treat them temporarily as “regional endemic species”. Only 141 species were shared among all three regions, accounting for a mere 7.4%. Tropical Africa and tropical America had the greatest number of shared species and the highest Sørensen similarity index (SC) value. Tropical forests had a higher species richness compared with temperate to boreal forests of the Northern Hemisphere, and in addition, also a higher proportion of white rot polypores compared to brown rot and ectomycorrhizal species. This study outlines the distribution patterns and species diversity of polypores in the world, shedding light on their ecological significance in diverse ecosystems.

Tuber rugosum, a new species from northeastern North America: Slug mycophagy aides in electron microscopy of ascospores

ABSTRACT Species in the genus Tuber are ascomycetous fungi that produce hypogeous fruiting bodies commonly called truffles. These fungi are ecologically relevant owing to the ectomycorrhizal symbiosis they establish with plants. One of the most speciose lineages within Tuber is the Rufum clade, which is widely distributed throughout Asia, Europe, and North America and is estimated to include more than 43 species. Most species in this clade have spiny spores, and many still have not been formally described. Here, we describe T. rugosum based on multigene phylogenetic analysis and its unique morphological characters. Tuber rugosum (previously designated in literature as Tuber sp. 69) has been collected throughout the Midwest, USA, and Quebec, Canada, and is an ectomycorrhizal symbiont of Quercus trees, as confirmed through morphological and molecular analyses of root tips presented here. We also present a novel method for preparing Tuber ascospores for scanning electron microscope imaging that includes feeding, digestion, and spore excretion by the slug Arion subfuscus. Following this method, spores become free from ascus and other mycelial debris that could obscure morphological traits during their passage through the snail gut while maintaining ornamentation. Finally, we report the fatty acid analysis, a fungicolous species association, and we provide an updated taxonomic key of the Rufum clade.

Molecular identification and mapping of mixed root samples to species and individuals.

This article is a Commentary on Osborne et al. (2023), 238: 1305–1317.

Correlated evolution in an ectomycorrhizal host-symbiont system.

Mechanisms of diversification in fungi are relatively poorly known. Many ectomycorrhizal symbionts show preference for particular host genera or families, so host-symbiont selection may be an important driver of fungal diversification in ectomycorrhizal systems. However, whether ectomycorrhizal hosts and symbionts show correlated evolutionary patterns remains untested, and it is unknown whether fungal specialisation also occurs in systems dominated by hosts from the same genus. We use metabarcoding of ectomycorrhizal fungi collected with hyphal ingrowth bags from Nothofagus forests across southern New Zealand to investigate host-symbiont specialisation and correlated evolution. We examine how ectomycorrhizal communities differ between host species and look for patterns of host-symbiont cophylogeny. We found substantial differences in ectomycorrhizal communities associated with different host taxa, particularly between hosts from different subgenera (Lophozonia and Fuscospora), but also between more closely related hosts. Twenty-four per cent of fungal taxa tested showed affiliations to particular hosts, and tests for cophylogeny revealed significant correlations between host relatedness and the fungal phylogeny that extended to substantial evolutionary depth. These results provide new evidence of correlated evolution in ectomycorrhizal systems, indicating that preferences among closely related host species may represent an important evolutionary driver for local lineage diversification in ectomycorrhizal fungi.

The contribution of forest reserves and managed forests to the diversity of macrofungi of different trophic groups in European mixed coniferous forest ecosystem

We report the first robust estimate of macrofungal assemblages in European mixed coniferous forest to better understand species diversity under two management strategies (managed vs. not managed) and to rate the recovery of forest reserves, transformed from formerly managed stands, to their natural state. Following extensive repeated sampling in three regions of Poland, we found 318 fungal species from different trophic groups. The two forest management strategies showed similar cumulative fungal species richness and values for Shannon, evenness, and Simpson’s dominance indices, suggesting that both management strategies did not generate factors stimulating or limiting species richness and biodiversity. In contrast, site as well as forest management strategy affected the composition of all fungal trophic groups, with site being a stronger influencing factor. Different fungal ecological groups responded differently to environmental drivers, with ectomycorrhizal symbionts and parasites being more tightly linked to tree traits than saprotrophs, which were affected mostly by climate and substrate. Indicator species associated mainly with managed forests comprised predominantly wood-inhabiting fungi. Conservation-relevant species (red-listed in Poland) were noted in both forest reserves and managed forests; however, they predominated in the former. The results indicated a rather slow process of transformation of fungal communities in forest reserves originating from previously managed forests. The major conclusion of this study is that managed forests complement forest reserves in fungal diversity conservation.

Two new Russula species (fungi) from dry dipterocarp forest in Thailand suggest niche specialization to this habitat type

Dry dipterocarp forests are among the most common habitat types in Thailand. Russulaceae are known as common ectomycorrhizal symbionts of Dipterocarpaceae trees in this type of habitat. The present study aims to identify collections of Russula subsection Amoeninae Buyck from dry dipterocarp forests in Thailand. A multi-locus phylogenetic analysis placed Thai Amoeninae collections in two novel lineages, and they are described here as R. bellissima sp. nov. and R. luteonana sp. nov. The closest identified relatives of both species were sequestrate species suggesting that they may belong to drought-adapted lineages. An analysis of publicly available ITS sequences in R. subsect. Amoeninae did not confirm evidence of any of the new species occurring in other Asian regions, indicating that dry dipterocarp forests might harbor a novel community of ectomycorrhizal fungi. Macromorphological characters are variable and are not totally reliable for distinguishing the new species from other previously described Asian Amoeninae species. Both new species are defined by a combination of differentiated micromorphological characteristics in spore ornamentation, hymenial cystidia and hyphal terminations in the pileipellis. The new Amoeninae species may correspond to some Russula species collected for consumption in Thailand, and the detailed description of the new species can be used for better identification of edible species and food safety in the region.

Effects of microclimate on bolete species richness and biomass in a Northern Benin woodland

AbstractStudies examining the role of abiotic variables on fructification sequences of ectomycorrhizal symbionts (boletes), the extent and direction of these effects are quite rare in Africa. In the current study, we assessed the effects of microclimate on the distribution and productivity of boletes in Benin. Nine permanent plots of 2500 m2 each split into 25 subplots of 100 m2 were installed in three different vegetation types. The first vegetation type is dominated by Isoberlinia doka, the second by Isoberlinia tomentosa and the third by Uapaca togoensis. Abiotic variables, including soil temperature, air temperature, air relative humidity and soil moisture, were recorded every 30 min from June to October. Each plot was surveyed twice a week during the mushroom season over 3 years (2015, 2016 and 2017) to record the abundance and the fresh biomass. The effects of microclimate on boletes productivity were evaluated using generalised linear mixed models in R. Boletes give the largest natural production in July and the lowest in October. Only soil moisture has a significant negative influence on the abundance (p > 0.05). The fruiting periods of boletes are known according to the variability of the microclimatic parameters and the vegetation.

Variation in the chemical quality of woody supplements for nursery growing media affects growth of tree seedlings

Tree seedlings are produced in tree nurseries. However, nursery-grown seedlings often exhibit poor performance after outplanting due to the lack of adaptation to harsh natural conditions. These nursery-grown seedlings do not necessarily possess well-developed ectomycorrhizal symbionts, which help to obtain nutrients and increase resilience in exchange for seedling photoassimilated carbon. To improve the quality of the seedlings in natural conditions, we sowed spruce seeds on growing media with the addition of wood chips, i.e. stemwood chips or polyphenol- and resin acid-rich knotwood chips. Wood chips were chosen because they are common forest side-streams, and their compounds have shown a potential to improve mycorrhization and seedling fitness. Wood chips initially decreased the growth of seedlings. However, this effect levelled off with time and depended on the quality of the wood. Wood chips had no effect on mycorrhization. Further testing of the wood material showed that wood chips seemed to decrease seedling growth via nitrogen (N) immobilisation rather than a direct toxic effect. The phenomenon of N immobilisation on wood chips could be explored further to develop a slow-release N source, aptly reflecting N availability in natural conditions. Slow-release N source based on wood chips could be beneficial both to increase survival in natural conditions and for environment protection.

Metabarcoding of root-associated ectomycorrhizal fungi of Himalayan pindrow fir through morphotyping and Next Generation Sequencing

Abies pindrow (Royle ex D.Don) Royle (Himalayan pindrow fir) is an imperative conifer native to Kashmir Himalaya, where its mono-dominant forests provide vital ecosystem services, besides being dwelling to endangered flora and fauna. However, in the past few decades, these forests have relentlessly undergone unprecedented deforestation and degradation, and consequently, biodiversity and biotic interactions are jeopardized in these ecosystems. Ectomycorrhizal (ECM) fungi of this fir species may prove helpful in the successful restoration of structural organization and functional integrity of these degraded fir forests. Consequently, the present study was undertaken to explore and document the root-associated ectomycorrhizal symbionts of Himalayan pindrow fir through ectomycorrhizal root tip surveys for morphotyping together with Next Generation Sequencing (Illumina MiSeq) of ITS region of fungal nuclear ribosomal DNA. Fine ECM infected root tips were grouped into fourteen distinct morphotypes based on the morphological attributes, with the monopodial pyramidal type being the most abundant morphotype. The molecular characterization revealed high fungal diversity associated with the roots of Himalayan pindrow fir. A total of 2,51,158 reads were obtained, representing 136 OTUs, of which 62 have confirmed ectomycorrhizal status. In addition, fir roots were found to host a large suite of diverse fungal taxa, including saprotrophs, parasites, and pathogens. FUNGuild assigned 9 prominent guilds to the fungi associated with the fir roots, and ectomycorrhizal fungi represented the largest guild. OTUs belonging to division Basidiomycota were more abundant than those belonging to Ascomycota. Inocybe, Russula, Otidea, Sebacina, Chalara, Tomentella, Cenococcum and Wilcoxina were the abundant ECM forming genera. The results of this study can serve as baseline information for future research and pave the way for experimental evaluation of these ectomycorrhizal mutualists for their prospective use in ectomycorrhization and ECM-mediated forest restoration.

The Genus Leccinum (Boletaceae, Boletales) from China Based on Morphological and Molecular Data.

Leccinum is one of the most important groups of boletes. Most species in this genus are ectomycorrhizal symbionts of various plants, and some of them are well-known edible mushrooms, making it an exceptionally important group ecologically and economically. The scientific problems related to this genus include that the identification of species in this genus from China need to be verified, especially those referring to European or North American species, and knowledge of the phylogeny and diversity of the species from China is limited. In this study, we conducted multi-locus (nrLSU, tef1-α, rpb2) and single-locus (ITS) phylogenetic investigations and morphological observisions of Leccinum from China, Europe and North America. Nine Leccinum species from China, including three new species, namely L. album, L. parascabrum and L. pseudoborneense, were revealed and described. Leccinum album is morphologically characterized by the white basidioma, the white hymenophore staining indistinct greenish blue when injured, and the white context not changing color in pileus but staining distinct greenish blue in the base of the stipe when injured. Leccinum parascabrum is characterized by the initially reddish brown to chestnut-brown and then pale brownish to brown pileus, the white to pallid and then light brown hymenophore lacking color change when injured, and the white context lacking color change in pileus but staining greenish blue in the base of the stipe when injured. Leccinum pseudoborneense is characterized by the pale brown to dark brown pileus, the initially white and then brown hymenophore lacking color change when injured, and the white context in pileus and stipe lacking color change in pileus but staining blue in stipe when bruised. Color photos of fresh basidiomata, line drawings of microscopic features and detailed descriptions of the new species are presented.

Macrofungi of urban Tilia avenues and gardens in Hungary

Macrofungal investigations were performed in gardens and avenues planted with Tilia spp. between 2009 and 2020 in Hungary, focusing on the Budapest area. Lime tree (Tilia) is recently one of the most favorable commonly used ectomycorrhizal tree in urban landscaping in Budapest, similarly to other European cities. As a result of 71 sampling occasions in total 60 epigeous and hypogeous macrofungal species belonging to 22 families and 33 genera were documented. The nrDNA ITS barcoding region of 56 specimens was sequenced. Fifty-nine species were identified, while one interesting Inocybe sp. could not be determined. Phylogenetic analyses of the most frequently collected family, Inocybaceae, including three genera and 17 species were performed. The genera Russula and Tomentella, two preferred ectomycorrhizal symbionts of Tilia in urban environments were also analyzed. Inocybe alluvionis, I. amelandica, Mallocybe siciliana and Pseudosperma aureocitrinum were reported for the first time from Hungary. The taxonomic status of other species is also discussed.

Choices of ectomycorrhizal foraging strategy as an important mechanism of environmental adaptation in Faxon fir (Abies fargesii var. faxoniana)

Faxon fir (Abies fargesii var. faxoniana) is endemic to the cool and moist subalpine region of Southwest China, where the occurrence of warmer and drier climate may impose uncertain environmental constraints to its population stability and community scuccession. Here we determine the role of root-mycorrhizal symbiosis in the adaptability of Faxon fir to varying environmental conditions. The traits and foraging behaviors of the ectomycorrhizal (ECM) associations in Faxon fir were investigated along elevational gradient in three representative natural distributional areas of the species. Soil and Faxon fir root samples were collected from varying elevations in three study areas, namely Wolong Nature Reserve, Miyaluo Nature Reserve, and Wanglang Nature Reserve, in Sichuan province, Southwest China, using point-centered quarter sampling method, with 32 samples for each elevational site. Measurements were made on fine root biomass, ECM morphological diversity and soil exploration types, density and superficial area of ECM root tips, and soil chemistry. Values for selective climatic variables were derived from the national grid-datasets of meteorology of China. Principle component analysis (PCA), redundancy analysis (RDA) and linear regressions were performed to determine the inter-relationships of ECM root traits with climatic and soil factors, and the variations of the ECM root traits with elevation. We found that the biomass of absorptive fine roots and ECM morphological diversity decreased with rising elevations and increasing soil water content or precipitation and soil C:N ratio. The foraging ability of ECM roots, inferred by the soil exploration type of ECM symbionts, and density and superficial area of ECM root tips, were weakened by warming and drying. Under conditions of low N availability, both the frequency of contact exploration type and ECM root tip density prevailed, whilst the frequency of both short-distance and medium-distance exploration types tended to decline, suggesting conservative carbon cost of ECM root systems in low fertility soil. Overall, our findings suggest that the ECM symbionts in Faxon fir adopt the strategy of C investment in root systems in response to warming and drying while relying on the functional efficiency of the ECM root tips toward the colder and more humid environments, and that Faxon fir may sustain moderate changes in the regional climate and maintain population stability, partially owning to adjustment of the ECM foraging strategies.

Management After Windstorm Affects the Composition of Ectomycorrhizal Symbionts of Regenerating Trees but Not Their Mycorrhizal Networks.

Due to ongoing climate change, forests are expected to face significant disturbances more frequently than in the past. Appropriate management is intended to facilitate forest regeneration. Because European temperate forests mostly consist of trees associated with ectomycorrhizal (ECM) fungi, understanding their role in these disturbances is important to develop strategies to minimize their consequences and effectively restore forests. Our aim was to determine how traditional (EXT) and nonintervention (NEX) management in originally Norway spruce (Picea abies) forests with an admixture of European larch (Larix decidua) affect ECM fungal communities and the potential to interconnect different tree species via ECM networks 15 years after a windstorm. Ten plots in NEX and 10 plots in EXT with the co-occurrences of Norway spruce, European larch, and silver birch (Betula pendula) were selected, and a total of 57 ECM taxa were identified using ITS sequencing from ECM root tips. In both treatments, five ECM species associated with all the studied tree species dominated, with a total abundance of approximately 50% in the examined root samples. Because there were no significant differences between treatments in the number of ECM species associated with different tree species combinations in individual plots, we concluded that the management type did not have a significant effect on networking. However, management significantly affected the compositions of ECM symbionts of Norway spruce and European larch but not those of silver birch. Although this result is explained by the occurrence of seedlings and ECM propagules that were present in the original forest, the consequences are difficult to assess without knowledge of the ecology of different ECM symbionts.

Nutrient trade-offs mediated by ectomycorrhizal strategies in plants: Evidence from an Abies species in subalpine forests.

Ectomycorrhizal (ECM) symbiosis is an evolutionary biological trait of higher plants for effective nutrient uptakes. However, little is known that how the formation and morphological differentiations of ECM roots mediate the nutrients of below‐ and aboveground plant tissues and the balance among nutrient elements across environmental gradients. Here, we investigated the effects of ECM foraging strategies on root and foliar N and P concentrations and N:P ratio Abies faxoniana under variations of climate and soil conditions.The ECM symbionts preferentially mediated P uptake under both N and P limitations. The uptake efficiency of N and P was primarily associated with the ECM root traits, for example, ECM root tip density, superficial area of ECM root tips, and the ratio of living to dead root tips, and was affected by the ECM proliferations and morphological differentiations. The tissue N and P concentrations were positively associated with the abundance of the contact exploration type and negatively with that of the short‐distance exploration type.Our findings indicate that the nutritional status of both below‐ and aboveground plant tissues can be strongly affected by ECM symbiosis in natural environments. Variations in the ECM strategies in response to varying environmental conditions significantly influence plant nutrient uptakes and trade‐offs.

Halimium as an ectomycorrhizal symbiont: new records and an appreciation of known fungal diversity

Halimium is a genus of Cistaceae, containing a small group of shrub species found in open vegetation types and in degraded forest patches throughout the western and central Mediterranean region. We recently described the morpho-anatomical features of the ectomycorrhizae formed by Scleroderma meridionale on Halimium halimifolium, but the mycorrhizal biology of this host plant genus is still largely unexplored. Here, we report new data on the ectomycorrhizal fungal symbionts of Halimium, based on the collection of sporocarps and ectomycorrhizal root tips in pure stands occurring in Sardinia, Italy. To obtain a broader view of Halimium mycorrhizal and ecological potential, we compiled a comprehensive and up-to-date checklist of fungal species reported to establish ectomycorrhizae on Halimium spp. on the basis of field observations, molecular approaches, and mycorrhiza synthesis. Our list comprises 154 records, corresponding to 102 fungal species and 35 genera, revealing a significant diversity of the Halimium ectomycorrhizal mycobiota. Key ectomycorrhizal genera like Russula, Lactarius/Lactifluus, Amanita, Inocybe, and Cortinarius account for more than half of all mycobionts. A large proportion of Halimium fungal species are shared with other host plants in various ecological settings, suggesting a critical role of common mycorrhizal networks in the function played by this shrub in various Mediterranean ecosystems.

Multigene phylogeny and taxonomic revision of Atheliales s.l.: Reinstatement of three families and one new family, Lobuliciaceae fam. nov.

Atheliales (Agaricomycetes, Basidiomycota) is an order mostly composed of corticioid fungi, containing roughly 100 described species in 20 genera. Members exhibit remarkable ecological diversity, including saprotrophs, ectomycorrhizal symbionts, facultative parasites of plants or lichens, and symbionts of termites. Ectomycorrhizal members are well known because they often form a major part of boreal and temperate fungal communities. However, Atheliales is generally understudied, and molecular data are scarce. Furthermore, the order is riddled with many taxonomic problems; some genera are non-monophyletic and several species have been shown to be more closely related to other orders. We investigated the phylogenetic position of genera that are currently listed in Atheliales sensu lato by employing an Agaricomycetes-wide dataset with emphasis on Atheliales including the type species of genera therein. A phylogenetic analysis based on 5.8S, LSU, rpb2, and tef1 (excluding third codon) retrieved Atheliales in subclass Agaricomycetidae, as sister to Lepidostromatales. In addition, a number of Atheliales genera were retrieved in other orders with strong support: Byssoporia in Russulales, Digitatispora in Agaricales, Hypochnella in Polyporales, Lyoathelia in Hymenochaetales, and Pteridomyces in Trechisporales. Based on this result, we assembled another dataset focusing on the clade with Atheliales sensu stricto and representatives from Lepidostromatales and Boletales as outgroups, based on ITS (ITS1–5.8S–ITS2), LSU, rpb2, and tef1. The reconstructed phylogeny of Atheliales returned five distinct lineages, which we propose here as families. Lobulicium, a monotypic genus with a distinct morphology of seven-lobed basidiospores, was placed as sister to the rest of Atheliales. A new family is proposed to accommodate this genus, Lobuliciaceae fam. nov. The remaining four lineages can be named following the family-level classification by Jülich (1982), and thus we opted to use the names Atheliaceae, Byssocorticiaceae, Pilodermataceae, and Tylosporaceae, albeit with amended circumscriptions.