Pseudotomentella sciastra Svantesson & Koljalg

Svantesson, Sten, Larsson, Karl-Henrik, Koljalg, Urmas, W. May, Tom, Patrik Cangren,, Henrik Nilsson, R. & Larsson, Ellen, 2019, Solving the taxonomic identity of Pseudotomentellatristis s. l. (Thelephorales, Basidiomycota) - a multi-gene phylogeny and taxonomic review, integrating ecological and geographical data, MycoKeys 50, pp. 1-77 : 36-38

Pseudotomentella sciastra Svantesson & Koljalg sp. nov. Fig. 15

Type.

SWEDEN. Småland: Jönköping, Svarttorp, Ramlaklint, boreonemoral, mixed, old-growth forest, on soil with intermediate pH, 12 September 2016, S. Svantesson 359 (holotype: GB!, GenBank Acc. No. ITS: MK290686).

UNITE SH.

SH030554.07FU

Etymology.

The name refers to the dark, star-like appearance of the spores.

Description.

Basidiomata annual, resupinate, membranaceous, effused - often to several tens of centimetres in diameter. Mature parts continuous, with a cottony texture when fresh and a rather firm, fibrous and compact, yet quite soft and elastic texture when dried. Hymenium smooth, but sometimes strongly undulating; blue grey when fresh and brown with a pinkish hue when dried. Immature parts discontinuous, byssoid with a cottony texture, both when fresh and when dried. Subhymenium and hymenium of immature parts blue grey when fresh or occasionally green or even yellow; blue grey to brown grey when dried. Subiculum well developed, loose, fibrous, pale orange brown to brown; often 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 absent from all hyphae.

Subicular hyphae noticeably long and straight, thick-walled; forming a loose tissue. Individual hyphae (3.9-) 4.4-6.6 (-6.8) μm wide, with a mean width of 5.0-5.8 μm; brown to orange brown in KOH, orange brown in water.

Subhymenial hyphae often somewhat sinuous, thin to thick-walled; forming a rather dense tissue. Individual hyphae 2.9-5.0 (-6.0) μm wide, with a mean width of 3.8-4.0 μm; hyaline to pale green in KOH, blue green in the presence of air; pale orange green to pale yellowish-green in water, with strongly granular contents.

Encrustation granular, probably amyloid (hard to observe due to the colour); blackish-brown in KOH, dark blue green in the presence of air; blackish-brown in water; scattered in occurrence on the upper parts of subhymenial hyphae and on the lower parts of basidia.

Basidia with four slightly curved sterigmata, occasionally two-sterigmate; clavate to narrowly clavate, sometimes clavopedunculate, thin-walled, with one-three slight constrictions. Dimensions: 42-67 (-68) × 7.3-9.0 (-9.3) μm; mean dimensions: 54-55 × 7.8-8.1 μm. Sterigmata (6.0-) 6.3-8.9 (-9.1) μm long, with a mean length of 7.4-7.9 μm. Colours and reactions the same as for the subhymenial hyphae, but in addition often with granular contents in KOH.

Cystidial organs lacking.

Basidiospores in frontal face with a subcircular basic shape and a star- or cross-shaped, sometimes angular to nodulose outline, covered in bi- or trifurcate, sometimes singularly attached, echinuli. Nearly all spores with four-six distinct, rounded to more often square lobes or rarely corners; abnormally large spores originating from two-sterigmate basidia infrequently occurring. Frontal dimensions: (6.0-) 6.1-7.9 (-8.1) × 6.3-8.2 μm; mean dimensions: 6.6-7.3 × 6.7-7.7 μm; Q-value: 0.9-1.1; mean Q-value: 1.0. Echinuli (0.5-) 0.6-1.2 (-1.4) μm long, with a mean length of 0.8-0.9 μm. Lateral face ellipsoid to ovoid, with evenly rounded edges or one-three lobes. Lateral dimensions: (6.2-) 6.5-7.7 (-8.0) × (4.3-) 4.4-6.0 (-6.2) μm; mean dimensions: 6.8-7.3 × 4.6-5.4 μm; Q-value: 1.2-1.6 (-1.7); mean Q-value: 1.3-1.5. Colour in KOH brown to yellow brown, in the presence of air often with a green to blue green reaction; in water pale greenish to pale greenish-orange; occasionally amyloid.

Chlamydospores lacking.

Habitat.

Recent Scandinavian collections have been made in mature to old coniferous, deciduous or mixed forests on soil with intermediate to high pH. Pseudotomentella sciastra has been found to form ectomycorrhiza with at least Castanea sativa , Cedrus libani , Neottia ovata , Picea abies and Quercus sp. ( Kõljalg et al. 2005, Nilsson et al. 2019).

Distribution.

Basidiomata encountered in: Estonia, Finland, Norway, Sweden, Turkey and the United Kingdom. Soil or root tip samples confirm presence also in: the Czech Republic, Mexico, Portugal (Madeira) and the United States.

Remarks.

All studied European specimens previously identified as P. atrofusca belong to P. sciastra . The two species display considerable morphological differences (see key).

Within the P. tristis group, the basidiomata of P. sciastra are recognised by their lack of hyphal cords and skeletal hyphae and their soft, yet rather firm and compact and ± elastic texture after drying, bluish to greenish colour of immature parts, wide subicular hyphae and small, star-shaped spores. Pseudotomentella pinophila is similar, but has narrower subicular hyphae and larger spores.

Additional specimens studied.

ESTONIA. Ida-Virumaa: Illuka, Puhatu Nature Reserve, Poruni primeval forest, wetlands, 1 October 2006, U. Kõljalg (TU 100644*); [Saare,] Saarema, Kihelkonna, Hülgera, Sampling area G4422, 25 September 2015, A. Saitta (TU 124211*, TU 124213*);

FINLAND. Etelä-Häme: Jyväskylä, Korpilahti, Oittila, on dead trunk of Ulmus glabra , 3 September 2014, U. Söderholm 4755 (H 6052710); Kanta-Häme: Lammi, Lammi Biological Station, Leib-rich forest, 12 September 2001, K.-H. Larsson (TU 108754*);

NORWAY. Oslo (county): Oslo (municipality), Bygdøy, Hengsåsen, boreonemoral, mixed forest on soil with high pH, 16 August 2010, K.-H. Larsson and N. Svensson (O F110317*); Østfold: Moss, Jeløya, boreonemoral, mixed forest on soil with high pH, 26 September 2010, S. Svantesson and N. Svensson (O F110318*); Oppland: Dovre, Grimsdalen, Austre Stakkstosætra, Pinus sylvestris forest, 26 August 2010, K.-H. Larsson and S. Svantesson (O F110301); Vestfold: Larvik, Kvelde, Jordstøyp, boreonemoral, mixed forest on soil with intermediate pH, 1 October 2010, K.-H. Larsson (O F110302); Ibidem, on soil with high pH, 1 September 2010, K.-H. Larsson and S. Svantesson (O F110303, F110304); Aust-Agder, Risør, Glupedalen, boreonemoral, mixed forest on soil with high pH, 10 September 2010, S. Svantesson and N. Svensson (O F110319, F110320, F110321); Aust-Agder: Tvedestrand, Eidbo, boreonemoral, mixed forest on soil with intermediate pH, 10 September 2010, S. Svantesson and N. Svensson (O F110322*); Oslo (county): Oslo (municipality), Gressholmen, boreonemoral, mixed forest on soil with high pH, 20 September 2010, S. Svantesson (O F110323, F110324); Oslo (county): Oslo (municipality), Killingen, boreonemoral, mixed forest on soil with high pH, 22 September 2010, S. Svantesson (O F110325); Buskerud: Ringerike, Ulltveit Nature Reserve, boreonemoral, coniferous forest on soil with high pH, 25 September 2010, S. Svantesson and N. Svensson (O F110326);

SWEDEN. Småland: Jönköping, Svarttorp, Ramlaklint, boreonemoral, mixed, old-growth forest, on soil with intermediate pH, 12 September 2016, S. Svantesson 360 (GB); Bohuslän: Tanum (municipality), Tanum (parish), Lammön, boreonemoral, deciduous forest on soil with high pH, 6 September 2016, S. Svantesson 312* (GB); Västergötland: Göteborg, Askim, Årekärrslunden, 24 October 2015, K.-H. Larsson 17308b* (GB); Dalsland, Mellerud, Skållerud, Österbo, mixed forest on soil with high pH, 20 September 2017, S. Svantesson 420* (GB); Ibidem, Norgekullen SW, coniferous forest on soil with high pH, 20 September 2017, S. Svantesson 423* (GB);

TURKEY. [Antalya: Elmalı,] Ciglikara, 2009, L. Tedersoo (TU 110153*); [Isparta:] Yukan-Gökdere [= Yukarı Gökdere], 2009, L. Tedersoo (TU 110113*);

UNITED KINGDOM. Scotland, Aberdeenshire: Inverurie, Burnhervie, in a small group of planted Populus trees, 16 September 2005, I. J. Alexander (TAA 187322*).