Pseudotomentella longisterigmata M.J.Larsen, Canad. J. Bot. 45: 1298 (1967)

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 : 50-53

Pseudotomentella longisterigmata M.J.Larsen, Canad. J. Bot. 45: 1298 (1967) Fig. 20

Type.

UNITED STATES. Washington: Olympic Peninsula, Sol Duc River, on coniferous wood, 25 August 1957, J. L. Lowe 8061 (holotype: BPI US0291345!; isotype: SYRF).

Description.

Basidiome annual, resupinate, membranaceous, effused to approximately ten centimetres in diameter. Mature parts continuous, with a cottony to rather firm, fibrous and compact, yet quite soft and elastic texture. Hymenium smooth; bluish-grey to brownish-grey. Immature parts discontinuous, byssoid with a cottony texture. Subhymenium and hymenium of immature parts bluish-grey. Subiculum well-developed, loose, fibrous, orange brown; forms the outer edge of the basidiome, 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 absent from all hyphae.

Subicular hyphae noticeably long and straight, thick-walled; forming a loose tissue. Individual hyphae 4.9-7.2 μm wide, with a mean width of 6.2 μm; orange brown to brown in KOH, orange to orange brown in water.

Subhymenial hyphae often somewhat sinuous, thin to thick-walled; forming a rather dense tissue. Individual hyphae (3.0-) 3.2-4.9 (-6.1) μm wide, with a mean width of 3.9 μm; pale brownish-green in KOH, blue green in the presence of air; brownish-green in water, with strongly granular contents.

Encrustation granular, probably amyloid (hard to observe due to the colour); dark brownish-green in KOH, dark blue green in the presence of air; blackish in water; scattered in occurrence on the upper parts of subhymenial hyphae and on the lower parts of basidia.

Basidia with four very long, slightly curved to hypha-like sterigmata, occasionally two-sterigmate; clavate or sometimes clavopedunculate, thin-walled, with one- three slight constrictions. Dimensions: (73-) 77-110 (-121) × (12.3-) 13.0-15.1 (-16.3) μm; mean dimensions: 91 × 13.9 μm. Sterigmata (11.2-) 11.7-17.9 (-19.3) μm long, with a mean length of 14.7 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. A majority of the spores with three-five indistinct lobes; unlobed subellipsoid or broadly ovoid spores present to a lesser extent, as well as subcircular, six or seven-lobed spores; abnormally large spores originating from two-sterigmate basidia infrequently occurring. Frontal dimensions: (9.7-) 10.0-11.7 × (9.4-) 9.8-11.7 μm; mean dimensions: 11.0 × 10.7 μm; Q-value: (0.9-) 1.0 (-1.1); mean Q-value: 1.0. Echinuli 1.2-1.8 (-2.1) μm long, with a mean length of 1.5 μm. Lateral face ellipsoid to ovoid, usually with evenly rounded edges, sometimes with one-three lobes. Lateral dimensions: 10.3-11.5 (-11.7) × (6.7-) 7.5-9.1 μm; mean dimensions: 10.9 × 8.5 μm; Q-value: 1.2-1.6; mean Q-value: 1.3. Colour in KOH pale brown to pale greenish-brown, in the presence of air often with a green to blue green reaction; in water brown; occasionally amyloid.

Chlamydospores lacking.

Habitat.

The only specimen of P. longisterigmata recorded to date is the type collection, which was collected on coniferous wood in a coastal forest in the state of Washington, United States.

Distribution.

Basidiomata encountered in: the United States.

Remarks.

The type collection is large and in seemingly good condition but repeated attempts at obtaining a useful DNA sequence from it proved unfruitful. The specimen exhibits a peculiar morphology, where the basidia carry sterigmata that are unusually long for the P. tristis group. They are often cylindrical rather than tapering and hence resemble generative hyphae - a growth form that basidia are sometimes seen reverting into in corticioid basidiomata formed under unfavourable conditions. It is therefore doubtful whether P. longisterigmata is a true species, but since this presently cannot be ascertained and, in order to stimulate its recollection, the name is here retained as a separate species.

There are relatively few spores in the hymenium of the holotype and many of them are immature. A more mature fruiting body of the species would hence probably have a browner colour.

Within the P. tristis group, the basidiome of P. longisterigmata can be recognised by its lack of hyphal cords and skeletal hyphae, its soft, yet rather firm and compact and ± elastic texture after drying, bluish to greenish colour of immature parts, wide subicular hyphae, large spores and long sterigmata. Pseudotomentella alobata , P. pluriloba and P. abundiloba are similar but all have smaller spores and shorter sterigmata.