Pseudotomentella pinophila 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 : 27-31

Pseudotomentella pinophila Svantesson sp. nov. Fig. 12

Type.

SWEDEN. Småland: Jönköping, Svarttorp, Ramlaklint, boreonemoral, mixed, old-growth forest, on soil with intermediate pH, 12 September 2016, S. Svantesson 358 (holotype: GB!, GenBank Acc. No. ITS: MK290708).

UNITE SH.

SH005337.07FU

Etymology.

The name refers to the ectomycorrhizal association of the species, which often seems to be with Pinus .

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; pale brown to pale greenish-brown when fresh, pale 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 to grey when fresh, pale blue or blue grey to dark blue grey or brown grey, sometimes with a green hue, when dried. Subiculum well-developed, loose, fibrous, pale 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 3.0-4.9 μm wide, with a mean width of 3.6-4.1 μm; pale orange brown to pale pinkish-brown in both KOH and water.

Subhymenial hyphae often somewhat sinuous, thin to thick-walled; forming a rather dense tissue. Individual hyphae (3.1-) 3.2-4.7 (-5.2) μm wide, with a mean width of 3.9-4.0 μm; hyaline to pale green or occasionally pale brown in KOH, blue green in the presence of air; pale green to pale orange in water, with strongly granular contents; sometimes with an amyloid reaction in the cell walls.

Encrustation granular, amyloid; bluish-black in both KOH and 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: (53-) 58-74 (-83) × (9.0-) 9.1-11.7 (-12.1) μm; mean dimensions: 65-67 × 9.9-10.3 μm. Sterigmata (8.2-) 8.8-10.5 (-11.9) μm long, with a mean length of 9.6-10.0 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 commonly with a subcircular basic shape and a roundedly star-shaped, sometimes roundedly cross-shaped or angular to nodulose outline, covered in bi- or trifurcate, occasionally singularly attached, echinuli. Lobes distinct, rounded to square; predominantly five, but commonly also three or four; six-lobed or subellipsoid, unlobed spores and spores with corners instead of lobes infrequently occurring, as well as abnormally large spores originating from two-sterigmate basidia. Frontal dimensions: (7.7-) 7.9-10.2 (-10.3) × (7.7-) 8.3-10.1 (-10.2) μm; mean dimensions: 8.6-9.1 × 8.8-9.4 μm; Q-value: 0.9-1.1; mean Q-value: 1.0. Echinuli (0.6-) 0.8-1.4 (-1.5) μm long, with a mean length of 0.9-1.1 μm. Lateral face ellipsoid to ovoid, usually with evenly rounded edges, sometimes with angular edges or one-three lobes. Lateral dimensions: (8.2-) 8.3-9.7 (-9.8) × (5.7-) 5.8-6.8 (-7.0) μm; mean dimensions: 8.7-9.0 × 6.3-6.6 μm; Q-value: 1.3-1.6; mean Q-value: 1.3-1.4. Colour in KOH pale green to orange brown, in the presence of air sometimes with a blue green reaction; in water pale green to orange brown or brown; occasionally amyloid.

Chlamydospores lacking.

Habitat.

Data on habitat are scarce to date, but recent Scandinavian collections have been made in old coniferous or mixed forests on soil with high pH. Pseudotomentella pinophila has been found to form ectomycorrhiza with at least Pinus densiflora , Pinus massoniana , Pinus sylvestris and Pinus thunbergii ( Kõljalg et al. 2005, Nilsson et al. 2019). It should be noted however that, although the only hitherto documented hosts of P. pinophila belong to the genus Pinus and P. sylvestris has indeed been present at nearly all Nordic localities of collection, a few of these collections were made at localities where Pinus was not recorded as a possible host.

Distribution.

Basidiomata encountered in: Norway and Sweden. Soil or root tip samples confirm presence also in: China and Republic of Korea.

Remarks.

Within the P. tristis group, the basidiomata of P. pinophila can be 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, narrow subicular hyphae, brown mature hymenium, long, laterally narrow and commonly star-shaped spores. Pseudotomentella sciastra , P. pluriloba and P. media can appear similar. Even though P. sciastra has star-shaped spores, it also has wider subicular hyphae than P. pinophila and, while P. pluriloba and P. media both share the characters of narrow hyphae, long spores and hymenia that are brown when mature with P. pinophila , they differ by having angular-nodulose spores, which are also laterally wider than the spores of P. pinophila .

Additional specimens studied.

NORWAY. Akershus: Asker, Skaugumåsen, boreonemoral, mixed forest on on soil with high pH, 23 September 2010, S. Svantesson (O F110327); Oslo (county): Oslo (municipality), Bygdøy, Hengsåsen, boreonemoral, mixed forest on soil with high pH, 22 September 2010, S. Svantesson (O F110328*); Oslo (county): Oslo (municipality), Gressholmen, boreonemoral, mixed forest on soil with high pH, 20 September 2010, S. Svantesson (O F110329); Telemark: Bamble, Rognsflaugane, boreonemoral, mixed forest on soil with high pH, 2 September 2010, K.-H. Larsson and S. Svantesson (O F110305); Akershus: Asker, Esvika, Løkenes, boreonemoral, mixed forest on soil with high pH, 15 August 2010, K.-H. Larsson and N. Svensson (O F110330*);

SWEDEN. Västergötland: Götene, Österplana, Hönsäter, coniferous forest on soil with high pH, 14 September 2017 S. Svantesson 418*, 419* (GB); Öland: Borgholm, Böda, Hagudden, mixed forest on soil with high pH, 5 October 2017 S. Svantesson 440* (GB).