Hebeloma fuscatum Beker & U. Eberh.; Beker, Eberhardt & Vesterholt, Fungi Europ. (Alassio) 14: 133, 2016.

Eberhardt, Ursula, Beker, Henry J., Borgen, Torbjorn, Knudsen, Henning, Schuetz, Nicole & Elborne, Steen A., 2021, A survey of Hebeloma (Hymenogastraceae) in Greenland, MycoKeys 79, pp. 17-118 : 17

Hebeloma fuscatum Beker & U. Eberh.; Beker, Eberhardt & Vesterholt, Fungi Europ. (Alassio) 14: 133, 2016. Fig. 12

Macroscopic description.

Cap 0.7-2.5 cm in diameter, convex to umbonate, margin smooth, tacky when moist, not hygrophanous, uniformly colored or more often bicolored, at center sepia to fuscous or dark brick, sometimes with a thin tomentum, at margin dark olive buff to cinnamon or umber; sometimes with remains of universal veil, partial veil present. Lamellae yellowish ochre then brown, emarginate, maximum depth 4 mm, number of lamellae {L} 24-32, droplets absent, white fimbriate edge usually present, but weak. Stem 0.8-7.0 × 0.15-0.5 {median} cm, whitish or pale grayish then browner to gray brown, not darker towards the base, cylindrical, stem Q 4-13, fibrillose, pruinose at apex. Context firm, stem interior stuffed, later hollow, flesh usually discoloring from base. Smell usually raphanoid but sometimes without smell; taste not recorded. Spore deposit color not recorded.

Microscopic description.

Spores amygdaloid, limoniform, occasionally ovoid, papillate, on ave. 12.5-13.5 × 7.0-7.5 µm, ave. Q = 1.6-1.9, brown, guttulate, almost smooth to weakly ornamented (O1O2), perispore not or hardly loosening (P0 (P1)), weakly to rather strongly dextrinoid (D2D3). Basidia 27-33(-36) × 8-9 µm, ave. Q = 3.0-4.1, mostly four-spored. Cheilocystidia usually lageniform or ventricose, occasionally cylindrical, occasionally characteristically with an apical, basal or median thickening, on ave. 41-51 × 4-7 (apex) × 4.5-6 (middle) × 8-13 (base) µm, ratios A/M = 0.9-1.13, A/B = 0.48-0.67, B/M = 1.75-1.97. Epicutis an ixocutis of 30 µm thickness (measured from exsiccata), maximum hyphae width 5-6 µm, sometimes encrusted, shape of trama elements beneath subcutis sausage-shaped and up to 19 µm wide. Caulocystidia similar to cheilocystidia, but less ventricose and very fragile, up to 75 µm long.

Collections examined.

S-Greenland: Paamiut, Churchyard, 62°N, 49.67°W, 26 Jul 1985, D. Boertmann (DB 85-21, C-F-119783), 25 m, with Salix glauca . W-Greenland: Kangerlussuaq, SE of Ravneklippen, 67.00°N, 50.67°W, 29 Aug 2018, T. Borgen (TB18.243, C-F-112530), 200 m, with Salix sp. in fen. Sisimiut, Præstefjeld, 66.96°N, 53.74°W, 17 Aug 2016, S.A. Elborne (SAE-2016.072-GR, C-F-106737), 300 m, with Salix herbacea and Bistorta vivipara . Upernavik, 72.79°N, 56.14°W, 18 Aug 2012, D. Boertmann (DB 12.047, C-F-115623), 0 m, in churchyard. E-Greenland: Jameson Land, Nerlerit Inaat/Constable Pynt, around the airport, 70.74°N, 22.64°W, 31 Jul 2017, H. Knudsen (HK17.009A, C-F-104897), 50 m. Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gåseelv valley, 70.77°N, 22.72°W, 11 Aug 2017, S.A. Elborne (SAE-2017.215-GR, C-F-106768), 40 m, with Salix arctica along riverside. Jameson Land, Nerlerit Inaat/Constable Pynt, Gåseelv valley, north side, 70.76°N, 22.69°W, 4 Aug 2017, H. Knudsen (HK17.091, C-F-104987), 160 m, with Salix sp. in tundra. Jameson Land, Nerlerit Inaat/Constable Pynt, Primulaelv, 70.74°N, 22.67°W, 13 Aug 2017, T. Borgen (TB17C.129, C-F-106783), 180 m, with Betula and Salix in heathland.

Distribution.

Recently described and still only recorded from a few alpine and arctic areas in Europe and arctic Canada ( Beker et al. 2016). The Greenland collections are from the Low Arctic zone and High Arctic zone, but the species is rare and scattered. Circumpolar, arctic-alpine.

Habitat and ecology.

Eight collections, six with Salix glauca , S. arctica and S. herbacea , two with undetermined Salix sp. The presence of Bistorta and Betula are mentioned, each on one occasion. Soil conditions are variable, but mostly calcareous. Salix was the only host mentioned by Beker et al. (2016). Some recent records from subalpine woodlands in central Europe suggest it may also associate with conifers ( Grilli et al. 2020).

Figures

Figure 12. Hebeloma fuscatum A SAE- 2016.072, photograph S. A. Elborne B distribution of cited collections C spores x 1600 and D cheilocystidia x 1000 of SAE- 2016.072 in Melzer's reagent. Scale bars: 5 µm; microphotographs H. K. J. Beker.