Pseudotomentella abundiloba 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 : 16-17

Pseudotomentella abundiloba Svantesson sp. nov. Fig. 7

Type.

NORWAY. Oslo (county): Oslo (municipality), Bygdøy, Hengsåsen, boreonemoral mixed forest on soil with high pH, 22 September 2010, S. Svantesson (holotype: O F110312!, GenBank Acc. No. ITS: MK290731).

UNITE SH.

SH032598.07FU

Etymology.

The name refers to the spores, which are abundantly lobed.

Description.

Basidiomata annual, resupinate, membranaceous, effused to several tens of centimetres in diameter. Mature parts continuous, with a rather firm, fibrous and compact, yet quite soft and elastic texture. Hymenium smooth, but sometimes strongly undulating; brown with a pinkish hue. Immature parts discontinuous, byssoid, with a cottony texture. Subhymenium and hymenium of immature parts blue grey to brown grey. Subiculum well developed, loose, fibrous, orange brown; often forms the outer edge of basidiomata, extending noticeably beyond the hymenium. All characters recorded in dried state.

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

Hyphal system monomitic; clamp connections and reaction in Melzer’s reagent absent from all hyphae.

Subicular hyphae noticeably long and straight, thick-walled; forming a loose tissue. Individual hyphae (4.3-) 4.8-6.9 (-7.2) μm wide, with a mean width of 5.5-6.1 μm; orange brown to dark brown in both KOH and water.

Subhymenial hyphae often somewhat sinuous, thin to thick-walled; forming a rather dense tissue. Individual hyphae (4.0-) 4.1-6.8 (-7.2) μm wide, with a mean width of 5.5-5.7 μm; in the upper parts, hyaline to orange brown or orange green in KOH, with a blue green reaction in the presence of air; in the lower parts, pale orange brown to orange brown in KOH, unchanged in air; in water with strongly granular contents, orange green.

Encrustation granular, inamyloid; hyaline to orange brown or orange green in KOH, blue green in the presence of air; orange green in water; common to rare, usually 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-) 64-92 (-93) × (8.7-) 10.0-14.4 (14.9) μm; mean dimensions: 70-81 × 11.0-12.0 μm. Sterigmata (8.4-) 9.0-12.9 (-13) μm long, with a mean length of 10.0-11.5 μm. Colours and reactions the same as for the upper parts of 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 a star-shaped, angular, nodulose or sometimes cross-shaped outline, covered in bi- or trifurcate, sometimes singularly attached, echinuli. Nearly all spores with four-seven, low but distinct, rounded to square lobes or corners; unlobed, broadly ovoid spores and rounded, heart-shaped spores infrequently occurring, as well as abnormally large spores originating from two-sterigmate basidia. Frontal dimensions: (8.8-) 9.2-10.5 × (8.0-) 8.6-10.7 (-10.8) μm; mean dimensions: 9.8 × 9.5-9.6 μm; Q-value: 0.9-1.2; mean Q-value: 1.0. Echinuli (0.9-) 1.1-1.8 (-1.9) μm long, with a mean length of 1.2-1.5 μm. Lateral face ellipsoid to semicircular, usually with evenly rounded edges, sometimes with one-three lobes. Lateral dimensions: (8.9-) 9.3-10.1 (-10.5) × (6.7-) 7.0-8.1 (-8.2) μm; mean dimensions: 9.7-9.8 × 7.3-7.7 μm; Q-value: 1.2-1.4 (-1.5); mean Q-value: 1.3. Colour in KOH pale orange green to orange brown, in the presence of air sometimes with a blue green reaction; in water pale orange green; inamyloid.

Chlamydospores lacking.

Habitat.

The type collection was obtained in an old, mixed forest on soil with high pH. No additional sequences are available in UNITE.

Distribution.

Basidiomata encountered in: Estonia and Norway.

Remarks.

Within the P. tristis group, the basidiomata of P. abundiloba 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, abundantly lobed spores and inamyloid encrustation on subhymenial hyphae and basidia. Pseudotomentella abundiloba , P. pluriloba and P. media can appear similar, but none of them has abundantly lobed spores. Pseudotomentella media further differs by having smaller spores and narrower subicular hyphae, while P. pluriloba has narrower subicular hyphae, longer sterigmata and frontally wider spores and P. alobata has amyloid encrustation on its subhymenial hyphae and basidia.

Additional specimens studied.

ESTONIA. Lääne: Ridala, between Uneste and Võnnu, Ehmja-Turvalepa Special Conservation Area, nutrient-rich, boreonemoral forest, 25 September 2012, L. Tedersoo (TU 110852*).