Pseudotomentella alobata Svantesson

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 : 21-22

Pseudotomentella alobata Svantesson sp. nov. Fig. 9

Type.

SWEDEN. Dalsland, Mellerud, Skållerud, Norgekullen SW, coniferous forest on soil with high pH, 20 September 2017, S. Svantesson 425 (holotype: GB!, GenBank Acc. No. ITS: MK290696).

UNITE SH.

SH030577.07FU

Etymology.

The name refers to the spores, which commonly lack lobation.

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; brown, purplish-brown or blue-greyish-brown when fresh, 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 to blue grey when fresh and blue grey to brown grey when dried. Subiculum well developed, loose, fibrous, orange 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 (4.3-) 4.6-7.4 (-7.6) μm wide, with a mean width of 5.6-5.9 μm; orange in both KOH and water.

Subhymenial hyphae often somewhat sinuous, thin to thick-walled; forming a rather dense tissue. Individual hyphae (3.1-) 3.4-6.9 μm wide, with a mean width of 4.0-4.5 μm; hyaline to pale green in KOH, blue green in the presence of air; yellow to pale orange yellow in water, with strongly granular contents.

Encrustation granular, amyloid; purple in KOH, dark blue green in the presence of air; dark brown in water; usually common and 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: (63-) 64-91 (-98) × (10.2-) 10.5-14.2 (-14.3) μm; mean dimensions: 74-77 × 11.3-12.1 μm. Sterigmata 8.5-12.1 (-12.4) μm long, with a mean length of 10.0-10.3 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 generally with a subcircular basic shape and an unlobed or occasionally weakly pronounced, rounded, heart-shaped outline, covered in bi- or trifurcate, sometimes singularly attached, echinuli. Subcircular, three-five-lobed spores infrequently occurring, as well as abnormally large spores originating from two-sterigmate basidia. Frontal dimensions: (9.0-) 9.1-10.7 × (8.4-) 8.9-10.5 (-10.7) μm; mean dimensions: 9.7-10.1 × 9.5-9.8 μm; Q-value: (0.9-) 1.0-1.1; mean Q-value: 1.0. Echinuli 1.2-1.8 (-1.9) μm long, with a mean length of 1.4-1.7 μm. Lat eral face ellipsoid, usually with evenly rounded edges, sometimes with one-three lobes. Lateral dimensions: (8.9-) 9.1-10.3 × (6.5-) 6.7-8.2 μm; mean dimensions: 9.7-9.9 × 7.1-7.4 μm; Q-value: (1.2-) 1.3-1.5; mean Q-value: 1.3-1.4. Colour in KOH pale brownish-yellow, in the presence of air often with a blue green reaction; in water pale greenish-yellow to pale orange yellow; occasionally amyloid.

Chlamydospores lacking.

Habitat.

Data on habitat are scarce to date, but recent Scandinavian collections have been made in old growth coniferous or mixed forests on soil with high pH.

Distribution.

Basidiomata encountered in: Norway, Slovenia and Sweden. No sequences originating from soil or root tip samples in UNITE.

Remarks.

Within the P. tristis group, the basidiomata of P. alobata 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, long, unlobed spores and amyloid encrustation on subhymenial hyphae and basidia. Pseudotomentella abundiloba , P. pluriloba and P. media can appear similar, but none of them has spores which generally are unlobed. P. media further differs by having smaller spores and narrower subicular hyphae, while P. pluriloba has narrower subicular hyphae, longer sterigmata and frontally wider spores than P. alobata . Pseudotomentella abundiloba sometimes has encrusted subhymenial hyphae and basidia, but without amyloid reaction.

Additional specimens studied.

NORWAY. Telemark: Bamble, Rognsflaugane, boreonemoral, mixed forest on soil with high pH, 2 September 2010, K.-H. Larsson and S. Svantesson (O F110316*); Telemark: Tokke, Dalen, Huvestad, boreonemoral, mixed forest on soil with high pH, 28 September 2010, S. Svantesson and N. Svensson (O F110315*);

SLOVENIA. Radovljica: Triglav National Park, Pokljuka plateau, transition zone between secondary spruce forest (in parts with remnants of primary Fagus sylvatica /Acer pseudoplatanus forest) and natural Larix decidua stand with individual trees of Pinus mugo , Sorbus aucuparia and Salix sp., 1530 m a.s.l., 20 September 2012, U. Kõljalg (TU 115626*);

SWEDEN. Ångermanland: Edsele, Djupdalsmyran, Stordjupdalen, on Picea abies , 29 August 2002, K.-H. Larsson 11873* (GB 0087566).