Hypochnus sitnensis Bres., Atti Imp. Regia Accad. Roveretana. 3(1): 115 (1897)

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 : 40-42

Hypochnus sitnensis Bres., Atti Imp. Regia Accad. Roveretana. 3(1): 115 (1897)

Type.

SLOVAKIA [Hungary at the time of collection]. Prenčow, Sitno, infra filagorum, in trunco putr. Fagi, 11 September 1895, Andr. Kmet (holotype: S F15178!).

UNITE SH.

SH030560.07FU

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; blue grey to purplish-brown when fresh, blue grey or blue-greenish grey to brown, with a reddish hue, when dried. Immature parts discontinuous, byssoid with a cottony texture, both when fresh and when dried. Subhymenium and hymenium of immature parts blue green, blue or blue grey when fresh and pale grey blue or pale blue grey to grey blue or blue grey when dried, sometimes with a green hue. Subiculum well developed, loose, fibrous, 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 (4.5) 4.6-7.4 μm wide, with a mean width of 5.4-6.2 μm; orange brown to dark brown in KOH, orange brown to brown in water.

Subhymenial hyphae often somewhat sinuous, thin to thick-walled; forming a rather dense tissue. Individual hyphae 3.2-6.2 (7.2) μm wide, with a mean width of 3.9-4.5 μm; pale orange brown to pale green in KOH, blue green in the presence of air; pale green to pale greenish-orange in water, with strongly granular contents.

Encrustation granular, probably amyloid (hard to observe due to the colour); blackish 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 slightly curved sterigmata, occasionally two-sterigmate; clavate to narrowly clavate, sometimes clavopedunculate, thin-walled, with one-three slight constrictions. Dimensions: 51-76 (-84) × (8.1) 8.3-13.7 (-14.6) μm; mean dimensions: 56-62 × 9.6-11.6 μm. Sterigmata (8.0) 8.3-11.3 (13.3) μm long, with a mean length of 9.4-10.2 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 unlobed, angular, weakly nodulose or sometimes cross-shaped outline, covered in bi- or trifurcate, occasionally singularly attached echinuli. A majority of the spores normally unlobed or with three-five indistinct corners to rounded lobes; subcircular spores with more pronounced, sometimes square lobes or ovoid to subellipsoid spores also common in some specimens; subcircular, six-lobed spores infrequently occurring, as well as abnormally large spores originating from two-sterigmate basidia. Frontal dimensions: 7.7-9.1 (9.2) × 8.0-9.2 (9.6) μm; mean dimensions: 8.3-8.6 × 8.4-8.8 μm; Q-value: 0.9-1.1; mean Q-value: 1.0-1.1. Echinuli (0.8) 0.9-1.9 μm long, with a mean length of 1.4 μm. Lateral face ellipsoid to narrowly ovoid or sometimes semicircular in shape, usually with evenly rounded edges, sometimes with one-three lobes. Lateral dimensions: (7.7) 8.0-9.0 × (6.0) 6.1-6.8 (7.0) μm; mean dimensions: 8.3-8.5 × 6.3-6.5 μm; Q-value: 1.2-1.4 (-1.5); mean Q-value: 1.3. Colour in KOH brown to orange brown, in the presence of air often with a blue green reaction; in water greenish-orange to orange brown; occasionally amyloid.

Chlamydospores lacking.

Habitat.

Data on habitat are scarce to date, but recent Scandinavian collections have been made in mature to old deciduous or mixed forests on soil with intermediate to high pH. Pseudotomentella tristis has been found to form ectomycorrhiza with at least Betula pendula and Fagus sylvatica ( Kõljalg et al. 2005, Nilsson et al. 2019).

Distribution.

Basidiomata encountered in: Estonia, Finland, Norway, Slovakia, Slovenia and Sweden. Soil or root tip samples confirm presence also in: Germany.

Remarks.

We here select a Swedish specimen to serve as an epitype for both P. tristis and H. fuscata . This decision is based on four reasons: first, the present study has found P. tristis and H. fuscata to be conspecific; secondly, the lectotypes of these species were both collected in Finland (within the same county); thirdly we have found P. tristis to occur at several localities in both Finland and Sweden; and fourthly, the Swedish material chosen is both ampler and displays more variation with respect to maturity of the basidiome than the single available recent Finnish collection.

The type specimen of H. sitnensis was collected in Slovakia, i.e. far from the type locality of P. tristis . It displays the morphological characters of P. tristis , apart from the absence of an amyloid reaction in the encrusting material found on basidia and subhymenial hyphae. This might be an artefact of, for example, its drying conditions, time or intraspecific variation, but since the specimen is in too poor a condition to allow DNA sequencing with currently available methods, this cannot be ascertained. We therefore consider it a synonym of P. tristis and suggest it be epitypified in due course with locally sampled material that matches the type.

In the case of H. sitnensis , there is only one collection matching the locality and habitat description of the protologue as well as the collector stated. It predates the publication of the species. This collection must hence be regarded as a holotype.

P.A. Karsten 770 is the lectotype of H. fuscata , as designated by Larsen in Nova Hedwigia (1971), but his note has been placed in P.A. Karsten 769, which has created confusion amongst mycologists studying these specimens. Mature spores that fall within the morphological span of P. tristis can easily be found in all collections that match Karsten’s (1889) description of the species, with respect to locality and date. It would hence seem that the smooth, small, bluish spores he writes of in the protologue (see Introduction) probably were immature ones, studied in the presence of air.

Within the P. tristis group, basidiomata of P. tristis itself can be recognised by their lack of hyphal cords and skeletal hyphae and their soft, rather elastic texture after drying, bluish to greenish colour of immature parts, wide subicular hyphae, medium sized, commonly angular to nodulose spores and relatively long echinuli and sterigmata. Pseudotomentella tristoides is similar but has shorter echinuli and sterigmata, P. sciastra has smaller, star-shaped spores and H. rhacodium (only known from the type) has hard, brittle basidiomata after drying.

Additional specimens studied.

ESTONIA. Valga: Otepää, Kääriku, Välkjärve, 10 September 2012, U. Kõljalg (TU 115439*); Tartumaa: Võnnu, Terikeste, on fallen branch of Picea abies in mixed forest, 20 August 1996, U. Kõljalg (TAAM 159485*); Lääne: Vormsi, road from Diby to Norrby, deciduous forest with Betula and Corylus , 27 September 2008, U. Kõljalg (TU 108134*);

FINLAND. Kanta-Häme: Lammi, Lammi Biological Station, Leib-rich forest, 12 September 2001, U. Kõljalg (TU 108757*); Satakunta: Luvia, Säppi, on fallen decayed Betula , 11 September 2013, L. Kosonen 54/13* (TUR);

NORWAY. Møre og Romsdal: Nesset, Eikesdal, Ljåstranda, rich, deciduous forest, 18 September 2011, K.-H. Larsson 15084* (O); Oppland: Vinstra, Liadalen, rich, deciduous forest, 24 September 2013, K.-H. Larsson 16367* (O); Hedmark: Ringsaker, Liberget, 24 August 1984, K.-H. Larsson 5901 (GB 87563); Sogn og Fjordane: Stryn, Flostranda Nature Reserve, boreonemoral, deciduous forest on ground with high pH, 25 September 2013, K.-H. Larsson (O F110297*); Rogaland: Forsand, Rössdalen, boreonemoral, deciduous forest on ground with high pH, 29 September 2012, K.-H. Larsson and S. Svantesson (O F110298*); Oppland: Nord-Fron, Liadalane Nature Reserve, boreonemoral, deciduous forest on ground with intermediate pH, 24 September 2013, K.-H. Larsson (O F110299, F110300*);

SLOVENIA. Upravna enota Kočevje: Rahjenavski Rog virgin forest reserve, S and E edge of the reserve, beech-silver fir old growth forest, 21 September 2012, S. Kõljalg; U. Kõljalg (TU 115642*);

SWEDEN. Västerbotten: Vännäs (municipality), Vännäs (parish), Orrböle, boreal, mixed, secondary, mature forest, on ground with high pH, 28 August 2015, S. Svantesson 188 (GB); Dalsland: Ödskölt, S of lake Ivägsjön, on deciduous wood, 22 September 1990, K. Hjortstam 17197 (K.-H. Larsson private collection).