Pseudotomentella alnophila 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 : 17-21

Pseudotomentella alnophila Svantesson sp. nov. Fig. 8

Type.

NORWAY. Buskerud: Ringerike, Juveren N, boreonemoral Alnus incana forest on soil with intermediate pH, 25 September 2010, S. Svantesson and N. Svensson (holotype: O F110313!, GenBank Acc. No. ITS: MK290715).

UNITE SH.

SH218588.07FU

Etymology.

The name refers to the ectomycorrhizal association of the species, which always seems to be with Alnus .

Description.

Basidiomata annual, resupinate, membranaceous, effused. Mature parts continuous, with a soft cottony texture. Hymenium smooth; blue grey, sometimes with a slightly brown hue. Immature parts discontinuous, byssoid, with a soft cottony texture. Subhymenium and hymenium of immature parts pale blue grey to blue grey. Subiculum thin to 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 4.0-5.0 (-5.1) μm wide, with a mean width of 4.5 μm; orange brown to dark brown in KOH and orange to orange brown in water.

Subhymenial hyphae often somewhat sinuous, thin to thick-walled; forming a rather dense tissue. Individual hyphae (3.2-) 3.4-5 (-5.6) μm wide, with a mean width of 4.1 μm; hyaline to pale orange brown in KOH, blue green in the presence of air; pale green in water, with strongly granular contents.

Encrustation not seen.

Basidia with four slightly curved sterigmata, occasionally two-sterigmate; clavate to narrowly clavate, sometimes clavopedunculate, thin-walled, with one-three slight constrictions. Dimensions: (66-) 67-93 (-100) × (11.2-) 11.3-14.2 (-15.0) μm; mean dimensions: 83 × 12.8 μm. Sterigmata (9.5-) 11-14.5 (-14.8) μm long, with a mean length of 8.6 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; 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-) 9.0-10.1 (-10.4) × 9.2-10.2 (-10.6) μm; mean dimensions: 9.5 × 9.8 μm; Q-value: 0.9-1.0; mean Q-value: 1.0. Echinuli (0.8-) 0.9-1.7 μm long, with a mean length of 1.2 μm. Lateral face ellipsoid to ovoid, usually with evenly rounded edges, sometimes with one-three lobes. Lateral dimensions: 9.0-10.6 × (6.6-) 6.9-8.1 (-8.2) μm; mean dimensions: 9.6 × 7.7 μm; Q-value: 1.2-1.3 (-1.4); mean Q-value: 1.3. Colour in KOH pale orange brown to pale orange green, in the presence of air occasionally with a blue green reaction; in water pale green to pale orange green; inamyloid.

Chlamydospores lacking.

Habitat.

The only specimens recorded to date of P. alnophila is the type collection and one other collection from the same locality, which is a mature and, at the collection site pure, stand of Alnus incana on clay soil with intermediate pH. In addition, UNITE sequence metadata show that the species forms ectomycorrhiza with at least Alnus mandschurica ( Kõljalg et al. 2005, Nilsson et al. 2019).

Distribution.

Basidiomata encountered in: Norway. Soil or root tip samples confirm presence also in: China.

Remarks.

Within the P. tristis group, the basidiomata of P. alnophila can be recognised by their lack of hyphal cords and skeletal hyphae and their soft cottony texture after drying, bluish to greenish colour of immature parts, narrow hyphae, long spores, bluish-grey mature hymenium (sometimes with a slightly brown hue) and their association with Alnus . Pseudotomentella pluriloba , P. media and P. pinophila are similar, but they all have basidiomata that are compact and rather firm after drying and whose mature parts are some shade of brown, without any bluish hue. Pseudotomentella pluriloba also has slightly longer spores and echinuli and wider subicular hyphae, while P. media and P. pinophila have generally slightly smaller microcharacters. Pseudotomentella pinophila also has a different spore shape. In addition, neither of these species has been recorded as being associated with Alnus .

Additional specimens studied.

NORWAY. Buskerud: Ringerike, Juveren N, boreonemoral, Alnus incana forest on soil with intermediate pH, 25 September 2010, S. Svantesson and N. Svensson (O F110314).