Sistotrema is a genus with ectomycorrhizal species − confirmation of what sequence studies already suggested

The ectomycorrhizal status of Sistotrema sp. is shown by morphological–anatomical and molecular identification, confirming earlier reports about Sistotrema DNA in ectomycorrhizae (ECM). For molecular identification of the ECM nuclear rDNA ITS sequences obtained from mycorrhizal root tips and fruitbodies of Sistotrema sp. were compared. Blast searches using the Sistotrema sp. sequences as query were performed in GenBank and UNITE for comparison with previously published Sistotrema sequences. The morphological–anatomical characterization of the ECM used well-established protocols for the examination of all mantle parts and rhizomorphs in different sections and views including detailed illustrations. The ECM are irregularly monopodial–pyramidal, whitish ochre to yellow ochre, and woolly. Older ones become more greyish and silvery at some patches. Diagnostic anatomical characteristics are irregularly inflated emanating and rhizomorph hyphae, ampullately inflated clamps, and the occurrence of yellow drops within the hyphae. The plectenchymatous mantle shows ring-like arranged hyphae, and a slightly gelatinous matrix. The ECM of Sistotrema sp. are compared to those of other species that form distinctly ampullate hyphae in rhizomorphs, too. The anatomically most similar ECM to those of this Sistotrema specimen are those of Hydnum repandum.     

The ectomycorrhiza <Emphasis Type="Italic">Piceirhiza internicrassihyphis</Emphasis>: A weak competitor of <Emphasis Type="Italic">Cortinarius obtusus</Emphasis>?

The ectomycorrhiza (ECM) Piceirhiza internicrassihyphis on Picea abies is described in detail. It is yellowish brown to brown with a mantle of a transitional type between plectenchymatous and pseudoparenchymatous. The inner mantle layers show some thick-walled hyphae, often with a few of them growing in parallel. These thick-walled hyphae contain particles which turn brownish in Melzer’s reagent, and their septa and walls are partially amyloid. Rhizomorphs occur infrequently and are undifferentiated, and are composed of rather loosely woven hyphae of uniform diameter. This combination of characteristics has not yet been identified in any other ECM. The lack of cystidia and the presence of amyloidy suggest that this ECM is formed by a species of the family Thelephoraceae. Piceirhiza internicrassihyphis can be found associated with ECM of Cortinarius obtusus, and the hyphae of the latter species often grow on the surface of P. internicrassihyphis and can even cover the whole tip. Although there is a close association and possibly a penetration between these two fungi, it can be excluded that the thick-walled hyphae of the inner mantle layers originate from C. obtusus. Some emanating hyphae of C. obtusus ECM seem to interact with those of P. internicrassihyphis, as indicated by short, hyphal outgrowths which were found attached to the foreign hyphae.     

Characterization and identification of field ectomycorrhizae of Boletus edulis and Cistus ladanifer

Field ectomycorrhizae sampled under Boletus edulis and Cistus ladanifer have been characterized and described in detail based on standard morphological and anatomical characters. The described ectomycorrhiza has traits typical of Boletales: whitish with three differentiated plectenchymatous layers in the mantle in plan view forming ring-like structures and rhizomorphs with highly differentiated hyphae. The inflated, smooth cystidia-like clavate end cells on the surface of the rhizomorphs and their slightly twisted external hyphae are additional characterizing features. The Hartig net occupies 1 1/2 rows of cortical cells, partly reaching the endodermis. Not all hyphae have clamps. The identification of the fungal symbiont as B. edulis was confirmed by ITS rDNA sequence comparison between mycorrhizas and sporocarps. The singularity of this symbiotic association, as well as its ecological and practical implications, are discussed.     

Two sebacinoid ectomycorrhizae on Chinese pine

Sebacinoid fungi show a broad mycorrhizal capacity; therefore, they play a very important role in natural systems. Worldwide, fungi of Sebacinales are present under different environmental conditions and associate with diverse plant hosts, however, are hitherto poorly studied in China. Two sebacinoid ectomycorrhizae (ECM), Pinirhiza multifurcata and Pinirhiza nondextrinoidea, are described in detail morphologically and anatomically in the present study. They share a plectenchymatous outer mantle with multiply ramified hyphae in a gelatinous matrix, clampless, thin, thick-walled emanating hyphae with mostly Y-shaped ramifications and triangular inflations at the point of ramification. P. multifurcata and P. nondextrinoidea can be distinguished by thick cells in mantle layers, the ramification of emanating hyphae, the presence or absence of rhizomorphs, as well as the differing color reaction in Melzer's reagent. The putative molecular phylogenetic relationships of P. multifurcata and P. nondextrinoidea were inferred by analyses of the partial large subunit nuclear rDNA (nLSU); however, an affiliation to fungal species was not possible. This is the first report of sebacinoid ECM on Chinese pine.     

Spatial patterns of gene expression in the extramatrical mycelium and mycorrhizal root tips formed by the ectomycorrhizal fungus Paxillus involutus in association with birch (Betula pendula) seedlings in soil microcosms

Functional compartmentation of the extramatrical mycelium of ectomycorrhizal (ECM) fungi is considered important for the operation of ECM associations, although the molecular basis is poorly characterized. Global gene expression profiles of mycelium colonizing an ammonium sulphate ((NH4)2SO4) nutrient patch, rhizomorphs and ECM root tips of the Betula pendula-Paxillus involutus association were compared by cDNA microarray analysis. The expression profiles of rhizomorphs and nutrient patch mycelium were similar to each other but distinctly different from that of mycorrhizal tips. Statistical analyses revealed 337 of 1075 fungal genes differentially regulated among these three tissues. Clusters of genes exhibiting distinct expression patterns within specific tissues were identified. Genes implicated in the glutamine synthetase/glutamate synthase (GS/GOGAT) and urea cycles, and the provision of carbon skeletons for ammonium assimilation via beta-oxidation and the glyoxylate cycle, were highly expressed in rhizomorph and nutrient patch mycelium. Genes implicated in vesicular transport, cytoskeleton organization and morphogenesis and protein degradation were also differentially expressed. Differential expression of genes among the extramatrical mycelium and mycorrhizal tips indicates functional specialization of tissues forming ECM associations.     

Morphological-anatomical characterization and identification of Tomentella ectomycorrhizas

Over the last two decades, much information has been gathered on the ectomycorrhizal fungus community composition of plant associations of boreal, temperate, and tropical regions. Worldwide, Tomentella ectomycorrhizas (ECM) are often common and dominant in the mycorrhizosphere of coniferous and deciduous forests. They are present under different environmental conditions and associate with diverse plant hosts. Tomentella sporocarps, however, are rarely found aboveground, so Tomentella species are often missing from fungus community studies based on fruit-body presence. Tomentella is a resupinate genus of Thelephoraceae (Basidiomycota) forming black-brown, brown, yellow, or ochre ECM on the roots of gymnosperm and angiosperm trees, distinguished by typical morphological-anatomical characteristics (clamped hyphae, angular mantle, surface network, special rhizomorphs and cystidia). In this paper, we review the taxonomic position and morphological-anatomical characteristics of Tomentella ECM. A short summary of the microscopic features used for distinguishing tomentelloids during morphotyping and identification is presented in order to support molecular and ecological studies of ectomycorrhizal fungus communities.     

The use of laser scanning confocal microscopy to characterize mycorrhizas of Pinus strobus L. and to localize associated bacteria

 Laser scanning confocal microscopy (LSCM), light microscopy (LM) and epifluorescence microscopy (FM) were used to observe the extramatrical hyphae, mantle patterns and associated bacteria on mycorrhizal tips of Pinus strobus L. seedlings grown in pot cultures. Laccaria sp. and Tuber sp. formed ectomycorrhizas with Pinus strobus, while Phialophora finlandia Wang & Wilcox and E-strain (sensu Danielson 1982) formed ectendomycorrhizas. Distinct mantle patterns and cystidia were observed with greater resolution using LSCM, and intracellular hyphae were visualized in three dimensions. Trypan blue penetrated fresh whole mounts to 20 μm and was an excellent stain for visualizing fungal hyphae and bacteria with LSCM. Fluorescein isothiocyanate and acridine orange were used in conjunction with LSCM and FM to localize bacteria on ectomycorrhizal tips. With LSCM, bacteria were visible in the surface mucigel, and optical sectioning through the root tip showed that bacteria were also present within the mantle. LSCM is a non-intrusive and fast method for visualizing mycorrhizal structures and their associated bacteria on fresh, whole root tips. Accepted: 17 July 1996     

Four ectomycorrhizae of Pyronemataceae (Pezizomycetes) on Chinese Pine (<Emphasis Type="Italic">Pinus tabulaeformis</Emphasis>): morpho-anatomical and molecular-phylogenetic analyses

Morphological and anatomical characters of four ectomycorrhizae with affinities to the genera Humaria, Geopora, and Trichophaea of Pyronemataceae (Pezizomycetes, Ascomycota) on Chinese Pine (Pinus tabulaeformis) are described. The ectomycorrhizae are yellowish brown to brown, and have pseudoparenchymatous outer mantle layers and partially warty emanating hyphae with thick walls and without clamps. Intrahyphal hyphae are present, and no rhizomorphs are formed. The four ectomycorrhizae are distinguishable by differences in cell shape of outer mantle layers and the presence of cystidia. Ectomycorrhizae of a possible Humaria species (Pinirhiza humarioides) lack cystidia and have irregularly inflated cells on the outer mantle layer that are connected with thin septa. The two ectomycorrhizae showing probable affinities to Geopora species (“P. daqingensis” and “P. geoporoides”) possess row-like arranged cells in the outer mantle layer and cell heaps, and differ by the presence or absence of cystidia as well as by the structure of the inner mantle layers. Ectomycorrhizae likely having been formed by a Trichophaea species (“P. trichophaeoides”) have oval to polygonal cells and no cystidia. The possible taxa affiliations were assessed by molecular-phylogenetic analyses of the internal transcribed spacer (ITS) and partial large subunit (LSU) nrDNA. Morphological and anatomical characters are discussed against the background of the LSU phylogeny.     

New Neotropical Sebacinales Species from a Pakaraimaea dipterocarpacea Forest in the Guayana Region,Southern Venezuela: Structural Diversity and Phylogeography

Pakaraimaea dipterocarpacea, a member of the Dipterocarpaceae endemic in the Guayana region, is associated with a diverse community of ectomycorrhizal (ECM) fungi. Amongst the 41 ECM fungal species detected in a 400 m² P. dipterocarpacea ssp. nitida plot in Southern Venezuela, three species belonged to the Sebacinales. We tested whether ECM anatomotype characterization can be used as a feasible element in an integrative taxonomy in this diverse fungal group, where the relevance of fruitbody morphology for species delimitation seems limited. Using a combination of ECM morpho-anatomical characterizations and phylogenetic analyses based on nuclear ITS and LSU sequences, we report three new species. The main distinguishing features of Sebacina guayanensis are the yellowish cell walls together with conspicuous undifferentiated, uniform compact (type B) rhizomorphs. Staghorn-like hyphae are characteristic of S. tomentosa. The combination of clusters of thick-walled emanating hyphae, including hyphae similar to awl-shaped cystidia with basal dichotomous or trichotomous ramifications, and the presence of type B rhizomorphs were characteristic of a third, yet unnamed species. The three species belong to three different, possibly specifically tropical clades in Sebacinales Group A. The geographic distribution of phylogenetically related strains was wide, including a Dicymbe forest in Guyana and an Ecuadorian rainforest with Coccoloba species. We show that ECM morpho-anatomy can be used, in combination with other analyses, to delineate species within Sebacinales Group A. In addition to phylogenetic information, type B rhizomorphs observed in different Sebacinales clades have important ecological implications for this fungal group. The phylogeography of Sebacinales suggests that dispersion and host jump are important radiation mechanisms that shaped P. dipterocarpacea ECM fungal community. This study emphasizes the need for more sequence data to evaluate the hypothesis that phylogeographic relationships between neo- and paleotropical ECM fungal species could be attributed to the vicariance of cross-continental hosts such as the Dipterocarpacae.     

In situ and in vitro colonization of Cathaya argyrophylla (Pinaceae) by ectomycorrhizal fungi

Cathaya argyrophylla, a critically endangered conifer, is found to grow at four isolated areas located in subtropical mountains of China. To examine the involvement and usefulness of mycorrhizas for sustaining the population of this tree, we compared the root system, morphology, and structure of mycorrhizal roots of C. argyrophylla, which were collected from a natural stand and an artificial stand, each grown at a different location. More mycorrhizal roots were found for trees from an artificial stand. The presence of extramatrical mycelium, mantle, and Hartig net revealed that C. argyrophylla formed an ectomycorrhizal association in both sampling sites. Starch granules were found in mycorrhizal roots collected only from a natural stand. The aseptic synthesis of C. argyrophylla and Cenococcum geophilum was established for the first time in vitro. Typical ectomycorrhizas formed on seedlings on RM medium containing 0.1 g/l glucose, 5 weeks after inoculation. By light microscopy, the synthesized mycorrhizas showed a thin mantle from which emanated extramatrical hyphae and highly branched Hartig net. A simple, rapid, and convenient mycorrhiza synthesis system was developed, which facilitates further studies on ectomycorrhizal development of C. argyrophylla.     

A sheathing mycorrhiza between the tropical bolete Phlebopus spongiosus and Citrus maxima

Phlebopus (Ph.) spongiosus was recently described from several pomelo orchards (Citrus maxima) in southern Vietnam. This fungus was suspected to associate with pomelo plants as an ectomycorrhiza, although members of the genus Phlebopus have previously been presumed saprotrophic. To clarify this association, pomelo roots collected from the orchard (in situ roots), and those cultured with Ph. spongiosus (in vitro roots) in test tubes for 12 wk, were examined for ectomycorrhizal colonization. Both in vitro and in situ roots were analyzed for colonization using fungal LSU nuclear ribosomal DNA sequencing. The in situ roots exhibited the anatomical features of ectomycorrhizae: a thick fungal mantle, Hartig net, and extramatrical hyphae. The Hartig net, however, was very rare and showed discontinuous development. The in vitro association between Ph. spongiosus and C. maxima showed ectomycorrhiza-like structures, i.e., mantles and rhizomorphs in the plant roots, but no Hartig net development in the roots. Continuous hyphal penetration was restricted to the exodermis in both in situ and in vitro roots. Although the association between Ph. spongiosus and C. maxima could be considered ectomycorrhizal, its anatomy matches the unique feature known as sheathing mycorrhiza.     

Ecological and anatomical characterization of some Pinus patula ectomycorrhizas from Mpumalanga, South Africa

 Ectomycorrhizal (ECM) fungi are an important component of the Pinus patula Schlechdt. et Cham. forest ecosystem in Mpumalanga, South Africa. ECM roots are intimately associated with accumulated litter on the forest floor and four ECM isolates where examined to determine whether they provide plant access to inorganic and organic sources of nitrogen (N) and inorganic, complexed inorganic and organic sources of phosphorus (P). In in vitro studies, all isolates were found to utilize most of the organic N compounds and organic or complexed inorganic P compounds supplied. Thus, ECM fungi could play a significant role in providing N and P to P. patula, especially from sources to which the host plant would not normally have access. Temperature sensitivities and pH optima of the four isolates differed. Of the ECM isolates WITS 01 and WITS 06 were collected from a high-litter site; WITS 01 mycorrhizas, identified as Scleroderma citrinum, were white, smooth and dichotomously branched with smooth, pale yellow, differentiated rhizomorphs. The mantle was plectenchymatous with outer and inner layers showing ring-like arrangements of hyphal bundles. The Hartig net had a palmetti shape. The WITS 02 (not identified) mycorrhizas were brown with lighter coloured root tips, with simple to dichotomous branching, smooth with no distinct mantle and sparse hyphae occurred on the root surface. The Hartig net was palmetti type with lobed haustoria. The results are discussed in relation to ECM distribution and function in nutrient cycling. Accepted: 7 January 1999     

Ectomycorrhizae between <Emphasis Type="Italic">Alnus acuminata</Emphasis> H.B.K. and <Emphasis Type="Italic">Naucoria escharoides</Emphasis> (Fr.:Fr.) Kummer from Argentina

Field ectomycorrhizae of Naucoria escharoides on Alnus acuminata ("andean alder", "aliso del cerro") are described in detail for the first time. Naturally occurring ectomycorrhizal roots were sampled beneath sporocarps of N. escharoides. The samples were taken from four natural forest plots at two homogeneous A. acuminata sites (Tucumán and Catamarca Provinces, Argentina). The ectomycorrhizae were characterized morphologically and compared by means of PCR/RFLP analysis of the internal transcribed spacer region of the nuclear rDNA. The most important morphological features of the ectomycorrhizae are a white to pale yellow mantle, simple to monopodial branches, hyaline emanating hyphae, abundant hyphal bundles emerging more or less perpendicularly from a plectenchymatous mantle, and an acute or rounded apex with or without a mantle. N. escharoides fruitbodies have white basal mycelium with emanating hyphae similar to those of andean alder ectomycorrhizae. The RFLP profiles of sporocarps and mycorrhizae were the same.     

Characterization of Japanese Lactarius section deliciosi ectomycorrhizae: Toward the use of mycorrhizae for taxonomy and expansion of available cultures

We described the ectomycorrhizae (ECM) of the Japanese Lactarius section Deliciosi species L. akahatsu, L. hatsudake, L. laeticolor, and L. subindigo with the aim of promoting the use of mycorrhizae for taxonomy and expansion of available cultures. Lactarius tottoriensis (sect. Lactarius) was also included as a comparator. The ECM of the four species of sect. Deliciosi showed orange laticifers and plectenchymatous mantles, whereas those of L. tottoriensis showed white laticifers and pseudoparenchymatous mantles. The ECM of L. hatsudake and L. subindigo showed complex rhizomorphs with thicker walls and more developed vessel-like hyphae compared to the other three species. Cystidium-like cells were rarely found on the mantles of L. laeticolor and L. subindigo. Fungal cultures of the five Lactarius species from their ECM were morphologically characterized. Cultures produced laticifers on agar medium, but the five species showed different growth rates. Rhizomorphs of L. hatsudake and L. subindigo in cultures showed a similar morphology to their ECM. Molecular phylogenetic analyses of cultures from the ECM demonstrated that they were of the targeted Lactarius species and suggested the need for taxonomic studies of L. hatsudake, L. subindigo, and L. tottoriensis at the species and section levels.     

Distance-related semi-quantitative estimation of the extramatrical ectomycorrhizal mycelia of <Emphasis Type="Italic">Cortinarius obtusus</Emphasis> and <Emphasis Type="Italic">Tylospora asterophora</Emphasis>

Extramatrical mycelia of ectomycorrhizae (ECM) can markedly differ in their density, organization and extension as well as in their biomass. As these mycelia are very important for nutrient uptake, are sinks for carbohydrates and probably act as potential agents to interfere with mycelia of other ECM, a method allowing calculations of density, extension and amount of extramatrical mycelium could further ecological studies at different scales. As a first step synthesized ECM of Cortinarius obtusus and Tylospora asterophora, which represent two different ‘exploration types’ — T. asterophora belongs to the 'short distance exploration type’ and C. obtusus to the ‘medium distance exploration fringe subtype’ — were compared with respect to their extramatrical mycelia. To investigate the mycelial distribution in detail, flat rhizotrons filled with peat were used to synthesize the ECM on roots of Picea abies (Norway spruce). As both species form white mycelia, they contrast conspicuously to the dark brown peat substrate. This made it favourable to use CD-camera photographs and a consecutive image analysis of the bright mycelium in comparison to the dark background. For that, nine distance areas have been defined as the regions between nine concentric lines placed around the mantle surface of the ectomycorrhizal root (EMR). The distances between these lines were fixed in a regular manner as the square multiples of roughly one diameter of the EMR (0,27 mm). This resulted in lines representing distances of 1, 4, 9, 16, 25, 36, 49, 64, and 81 multiples of the EMR diameter. The distance of 81 EMR diameters equals roughly a real distance of app. 20 mm from the surface of the EMR. The studies showed highly significant differences in mycelial density between the four innermost distance areas, i. e. areas up to a distance of 16 EMR diameters. This applied for both species. Significant differences were found in the same areas when both species were compared. It was shown that C. obtusus still forms a considerable amount of mycelium beyond the 49 distance line, where the substrate was covered by 15–20 %. However, a limited data set did not allow any statistical calculations at these positions. In contrast to C. obtusus, the amount of extramatrical mycelium of T. asterophora decreased more rapidly with increasing distance. Mycelium could not be detected with this method beyond the 49 distance line. We conclude that these two species differ considerably in the amount and extension of their mycelia and this may be in line with their assignment to the respective exploration types. Further studies are needed to substantiate these results with additional species representing the full set of known exploration types. Envisaged correlation studies of these results with mycelial biomass by direct measurement of hyphal length or via quantitative PCR, can possibly result in an estimation of extramatrical mycelia of ECM in natural soil.     

Extramatrical structures of hydrophobic and hydrophilic ectomycorrhizal fungi

The extramatrical mycelia of Suillus bovinus, Rhizopogon luteolus and R. vinicolor, all examples of hydrophobic (ho), mat-forming mycorrhizal fungi, were examined while associated with their hosts in the unsterilized rhizoscope, and efforts were made to produce and examine similar structures in vitro. Comparisons were made with four hydrophilic (hi) mycorrhizal fungi, Thelephora terrestris, Cenococcum geophilum, Laccaria laccata and Hebeloma crustuliniforme. The ho fungi formed linear structures (coarse, rhizomorph-like cords, with vessels in the center) and fans, both in the rhizoscope and in vitro. The same was seen in mycorrhizal mycelia in forest soils. These cords did not themselves give rise to the fans peripherally, and were not proper rhizomorphs, but were created continuously from single exploring air hyphae in the preexisting fan. Thus the ho exploring hyphae aggregated into strands, which grew in thickness only when no suitable, exploitable substrate was found. The assembly of hyphae creating ho cords was seen in the air as well as on inert hydrophilic (glass) or hydrophobic (plastic) surfaces, but never in water. It is hypothesized that the ho cell wall surface glues hyphae together while cords are formed. Water disturbed strands and mantles already formed. The ho exploring hyphae could also create ho mycelial patches (as in a mat) at the water-air interface of a number of substrates. The periphery of these patches seemed to be composed of shorter exploiting hyphae penetrating different water-soaked substrates. Exploring, aerial hyphal tips of the ho fungi were shown to excrete water droplets from openings in the ho cell wall surface, both in vitro and in the rhizoscope. In the rhizoscope, droplet excretion was apparently directly governed by photosynthesis in the shoot of the seedling. It is proposed that the drop exudation represents a kidney-like function of the extramatrical hyphae and a bridge to drier soil particles to initiate nutrient uptake by the hyphae. The ecological function of the different extramatrical structures of ho fungi are discussed. The ho cords or hyphae may translocate water only in the vessels or symplastically and not in the cell walls. The ho property may be essential among the S-selected (stress-tolerant) factors in these forest fungi. The transfer from water-repelling exploring structures into more hi exploiting structures in water contact with surrounding soil debris is, therefore, of great importance. The hi fungi did not form rhizomorph-like strands, in most cases, but an extending hyphal mycelium, representing foraging, exploring and exploiting structures at the same time. In the field, short strands may be found. On the hi fungi droplets were also produced but readily fused into a water sheath around the hypha. The hyphae thus tended to wick water via the cell wall.     

Expression of the nitrate transporter nrt2 gene from the symbiotic basidiomycete Hebeloma cylindrosporum is affected by host plant and carbon sources

Although the function of the extramatrical mycelium of ectomycorrhizal fungi is considered essential for the acquisition of nitrogen by forest trees, gene regulation in this fungal compartment is poorly characterized. In this study, the expression of the nitrate transporter gene nrt2 from the ectomycorrhizal basidiomycete Hebeloma cylindrosporum was shown to be regulated by plant host and carbon sources. In the presence of a low fructose concentration, nrt2 expression could not be detected in the free-living mycelium but was high in the extramatrical symbiotic mycelium associated to the host plant Pinus pinaster. In the absence of nitrogen or in the presence of nitrate, high sugar concentrations in the medium were able to enhance nrt2 expression. Nevertheless, in the presence of high fructose concentration, high ammonium concentration still completely repressed nrt2 expression indicating that the nitrogen repression overrides sugar stimulation. This is the first report revealing an effect of host plant and of carbon sources on the expression of a fungal nitrate transporter-encoding gene.     

Studies in African thelephoroid fungi: 1. <Emphasis Type="Italic">Tomentella capitata</Emphasis> and <Emphasis Type="Italic">Tomentella brunneocystidia</Emphasis>, two new species from Benin (West Africa) with capitate cystidia

This paper presents Tomentella capitata and Tomentella brunneocystidia as new species based on molecular data and anatomical features. Both T. capitata and T. brunneocystidia form sister species with Tomentella pilosa. All three taxa are well supported by bootstrap values. Anatomically, T. capitata and T. brunneocystidia are very close and are similar in shape, size, ornamentation of basidiospores, and size and colour of subicular hyphae. Monomitic rhizomorphs sometimes covered by irregularly shaped thin hyphae are present in both species. Shape and pigmentation of the cystidia are the most discriminating features between T. capitata and T. brunneocystidia. The cystidia of T. capitata are maximum 35 μm long, show a distinctive globose apex and are sometimes covered with dark brown pigmentation and/or encrustation, whereas cystidia of T. brunneocystidia are bigger, up to 55 μm long, with a sub-capitate shape and dark blue to dark green contents all over their length. The differences to species, already described as having capitate and clavate cystidia, are discussed. A key for the identification of cystidioid Tomentella species is given. Taxonomical novelties: Tomentella capitata Yorou & Agerer, Tomentella brunneocystidia Yorou & Agerer.