Pseudotomentella pluriloba 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 : 31-32

Pseudotomentella pluriloba Svantesson sp. nov. Fig. 13

Type.

FINLAND. Uusimaa: Loviisa, Rutosinpyhtää, Marinkylä, rotten trunk on the ground ( Picea ), 30 September 2010, U. Söderholm 4263 (holotype: H 6018127!, GenBank Acc. No. ITS: MK290698).

UNITE SH.

SH030565.07FU

Etymology.

The name refers to the several lobes of the spores.

Description.

Basidiomata annual, resupinate, membranaceous, effused to approximately ten 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 to purplish-brown when fresh, reddish-brown when dried. Immature parts discontinuous, byssoid with a cottony texture, both when fresh and when dried. Subhymenium and hymenium of immature parts blue when fresh, blue grey to brown grey after drying. Subiculum well developed, loose, fibrous, brown with an orange hue; 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-) 4.0-5.9 (-6.8) μm wide, with a mean width of 6.8-5.1 μm; orange brown in both KOH and water.

Subhymenial hyphae often somewhat sinuous, thin to thick-walled; forming a rather dense tissue. Individual hyphae (2.7-) 2.9-5.3 (-5.4) μm wide, with a mean width of 4.0-4.2 μm; pale orange green to hyaline in KOH, blue green in the presence of air; pale orange green to hyaline in water, with strongly granular contents.

Encrustation granular, amyloid, concolourous with the hyphae in both KOH and 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: (55-) 58-87 (-94) × (10.3-) 10.7-13.3 (-13.4) μm; mean dimensions: 68-73 × 11.8-12.1 μm. Sterigmata (9.8-) 10.1-13.7 (-14.5) μm long, with a mean length of 11.5-12.3 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 angular to nodulose or sometimes cross-shaped outline, covered in bi- or trifurcate, sometimes singularly attached, echinuli. Nearly all spores with three-five distinct corners or rounded to square lobes; unlobed subcircular, unlobed subellipsoid or rounded, heart-shaped spores infrequently occurring, as well as abnormally large spores originating from two-sterigmate basidia. Frontal dimensions: (9.0-) 9.1-10.8 (-10.9) × (9.2-) 9.3-10.9 (-11.1) μm; mean dimensions: 9.8 × 10.2 μm; Q-value: 0.9-1.0 (-1.1); mean Q-value: 1.0. Echinuli (0.9-) 1.0-1.9 μm long, with a mean length of 1.4 μm. Lateral face ellipsoid, usually with evenly rounded edges, rarely with one-three lobes. Lateral dimensions: 9.0-10.4 (-10.8) × (6.7-) 6.8-8.5(8.6) μm; mean dimensions: 9.6-9.8 × 7.5-7.6 μm; Q-value: 1.2-1.4; mean Q-value: 1.3. Colour in KOH pale orange green, in the presence of air often with a pale blue green reaction; in water pale orange; occasionally amyloid.

Chlamydospores lacking.

Habitat.

Data on habitat are scarce to date, but recent Scandinavian collections have been made in mature to old coniferous or mixed forests on soil with intermediate pH. Pseudotomentella pluriloba has been found to form ectomycorrhiza with at least Pseudotsuga menziesii ( Kõljalg et al. 2005, Nilsson et al. 2019).

Distribution.

Basidiomata encountered in: Finland and Sweden. Soil or root tip samples confirm presence also in: Canada and the United States.

Remarks.

Within the P. tristis group, the basidiomata of P. pluriloba 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 noticeably narrower subhymenial hyphae, long, moderately lobed spores and amyloid encrustation on subhymenial hyphae and basidia. Pseudotomentella abundiloba , P. alobata and P. media can appear similar, but P. media differs by having smaller spores and narrower subicular hyphae which are ± the same width as its subicular hyphae, while P. abundiloba and P. alobata have frontally narrower spores with different lobation than P. pluriloba , as well as wider subicular hyphae and shorter sterigmata.

Additional specimens studied.

SWEDEN. Öland: Borgholm, Böda, Trollskogen, mixed forest on soil with intermediate pH, 5 October 2017, S. Svantesson 439* (GB).