Tomentella viridibasidia Svantesson, 2021

Svantesson, Sten, Larsson, Karl-Henrik & Larsson, Ellen, 2021, Pseudotomentella badjelanndana, Pseudotomentella sorjusensis and Tomentella viridibasidia-three new corticioid Thelephorales species from the Scandes Mountains, Phytotaxa 497 (2), pp. 61-78 : 72-75

Tomentella viridibasidia Svantesson , sp. nov. ( Fig. 5 )

MycoBank No.: MB835164. UNITE SH: SH1390022.08FU, SH1528566.08FU. Etymology: the name refers to the basidia, which often have a beautiful, green colour in KOH.

Type: SWEDEN. Lycksele Lappmark: Storuman, Tärna, Gieravaardo, subalpine Betula pubescens subsp. czerepanovii (N. I. Orlova) Hämet-Ahti forest with Salix L. bushes, on ground with high pH, on wood of Betula pubescens subsp. czerepanovii , 21 August 2015, S. Svantesson 100 (holotype: GB!, GenBank Acc. No. ITS: MT 146450 ).

Basidiomata annual, resupinate, adherent to the substratum, arachnoid to mucedinioid, sometimes granulose; effused— usually to 1–5 centimetres in diameter. Mature parts continuous, with a soft, cottony texture when fresh and a brittle, yet quite soft and elastic texture when dried. Hymenium smooth to granulose; commonly greenish brown when fresh, sometimes yellowish brown or brown, concolourous when dried. Immature parts discontinuous, arachnoid, with similar or slightly paler colour than the mature parts. Subiculum loose, fibrous, dark brown; initially thin, eventually becoming well developed; sometimes forms the outer edge of basidiomata, extending noticeably beyond the hymenium.

Hyphal cords lacking, but loose bundles of subicular hyphae sometimes present.

Hyphal system monomitic, clamp connections present on all hyphae, all hyphae inamyloid.

Subicular hyphae thick-walled, forming a loose tissue. Individual hyphae (4.9–) 5.0–6.5 (–6.7) μm wide, with a mean width of 5.7–5.9 μm; brown in both KOH and water.

Subhymenial hyphae often somewhat sinuous, thin to thick-walled; forming a rather loose tissue. Individual hyphae (3.7–) 4.0–6.4 (–6.6) μm wide, with a mean width of 5.1 μm; pale brown, pale orange brown or pale greenish brown in KOH, often with a green or sometimes blue green reaction in the presence of air; pale orange brown to orange brown in water, with strongly granular contents.

Encrustation minute, punctiform granules sometimes present on subicular hyphae; concolourous with the hyphae.

Basidia with four slightly curved sterigmata, occasionally two-sterigmate; clavate, thin-walled, often with one or two slight constrictions. Dimensions: (23–) 26–35 (–36) × (6.0–) 6.3–8.8 (–9.1) μm; mean dimensions: 28–30 × 7.5– 8.1 μm. Colours and reactions the same as for the upper parts of subhymenial hyphae, but colour reaction in presence of air often more prevalent and in addition contents sometimes granular in KOH.

Cystidial organs lacking.

Basidiospores generally pear-shaped, sometimes almost broadly ellipsoid, sometimes more equilaterally triangular and more prominently lobed; covered in singularly attached echinuli. Abnormally large spores originating from two-sterigmate basidia infrequently occurring. Frontal dimensions: (6.9–) 7.1–8.3 × (5.9–) 6.0–6.9 (–7.0) μm; mean dimensions: 7.3–7.6 × 6.4–6.5 μm; Q-value: 1.1–1.3; mean Q-value: 1.1–1.2. Echinuli (0.4–) 0.5–1.0 μm long, with a mean length of 0.6–0.7 μm. Lateral face bean-shaped to broadly ovoid, with evenly rounded edges. Lateral dimensions: (6.7–) 6.8–7.9 (–8.1) × (5.3–) 5.4–6.5 (–6.7) μm; mean dimensions: 7.2–7.6 × 5.6–6.0 μm; Q-value: 1.1–1.4; mean Q-value: 1.2–1.3. Colour in KOH pale brown to brown, sometimes with a green or orange hue, in the presence of air occasionally with a blue green reaction; in water pale orange brown to orange brown; inamyloid.

Chlamydospores lacking.

Habitat

Data on habitat are scarce to date, but recent Scandinavian collections have been made in subalpine Betula pubescens subsp. czerepanovii or Pinus sylvestris L. forests and low alpine heaths on ground with low to high pH. Tomentella viridibasidia has been found to form ectomycorrhiza with at least Abies Mill. sp., Dryas octopetala, Cephalantera austiniae (A. Gray) Heller, Pinus heldreichii H. Christ and Picea abies ( Kõljalg et al. 2005, Nilsson et al. 2018). Eight out of the ten root tip sample sequences present in UNITE come from arctic or mountainous localities, as well as four out of 42 extracted from soil samples, while the remaining sequences originate from temperate forests in lowland areas.

Distribution

Basidiomata encountered in: Norway and Sweden. Root tip samples confirm presence also in Norway (1), United States (3), Montenegro (1), France (1), Estonia (1), Canada (3) and soil samples in Estonia (35), Latvia (3), United States (4).

Remarks

It is currently unclear what the name T. stuposa represents genetically. Kõljalg (1996) designated a type in Herbarium B, “5539/74”, but since it is unknown whether this collection represents original material, so is its identity as a lectotype or a neotype. The collection concerned was requested from herbarium B, but could not be located by its staff. Even so, both the morphological concept of the species, according to e.g. Larsen (1974), Stalpers (1993), Kõljalg (1996), and Peintner & Dämmrich (2012), and the molecular use of the name, as reflected by UNITE SHs ( Kõljalg et al. 2005, Nilsson et al. 2018), is clearly different from the intended application of T. viridibasidia .

Tomentella viridibasidia has, in similarity to T. olivascens , T. stuposa and T. ruttneri , quite wide subicular hyphae, which, like their basidiomata, are some shade of brown. It differs, however, from T. stuposa and T. ruttneri by its smaller and differently shaped spores and the greenish tint to the brown colour of its basidiomata. T. olivascens is seemingly similar to T. viridibasidia in most morphological aspects but the basidiomata of T. viridibasidia are greenish brown at most, whereas those of T. olivascens are often bright green. Together with the slight difference in the width of their subicular hyphae and the more pronounced dissimilarity in subhymenial hyphal colour—hyaline to pale yellow in T. olivascens and pale orange brown to pale greenish brown in T. viridibasidia —morphological separation is well possible. Tomentella violaceofusca (Sacc.) M.J. Larsen , Tomentella , viridescens (Bres. & Torrend) Bourdot & Galzin , Tomentella donkii Litsch. and Tomentella pilatii Litsch. are also similar to T. viridibasidia to some extent, but differ in so many morphological aspects that the risk for confusion should be minimal.

Additional specimens studied

NORWAY. Oppland: Dovre, Grimsdalen, Tverråi S, low alpine heath on ground with low pH, on deciduous wood, 25 August 2010, K.- H. Larsson and S. Svantesson (O-F256717); Ibidem, Storberget N, subalpine Betula pubescens subsp. czerepanovii forest on ground with low pH, on deciduous wood, 26 August 2010, K.- H. Larsson and S. Svantesson (O- F 256714*, O-F256715, O-F256716); Ibidem, Storberget S, subalpine Betula pubescens subsp. czerepanovii forest on ground with low pH, on deciduous wood, 26 August 2010, K.- H. Larsson and S. Svantesson (O-F256719, O-F256720); Ibidem, Austre Stakkstosaetra, subalpine Pinus sylvestris forest on ground with low pH, 26 August 2010, K.- H. Larsson and S. Svantesson (O-F256718);

SWEDEN. Lule Lappmark : Jokkmokk, Unna Duvgge, low alpine heath on ground with high pH, on soil in roof of rodent (probably lemming) burrow, 15 August 2016, S . Svantesson 273, 275 ( GB); Ibidem, Sårjås N , low alpine heath on ground with intermediate pH, on underside of stone, 17 August 2016, S . Svantesson 297 * ( GB); Ibidem, Sårjås N , low alpine heath on ground with intermediate pH, on soil under stone, 17 August 2016, S . Svantesson 299 ( GB) .

Figures

FIGURE 5. Morphological features of T. viridibasidia, mounted in KOH and macroscopically.A, B basidiospores in frontal face; C, D in lateral face; E microscopic overview; F mature basidiome (holotype). The scale bar represents 10 µm.