Hebeloma minus Bruchet; Bull. mens. Soc. linn. Lyon 39(6(Suppl.)): 126, 1970.

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 minus Bruchet; Bull. mens. Soc. linn. Lyon 39(6(Suppl.)): 126, 1970. Fig. 28

Macroscopic description.

Cap 0.9-3.1 cm in diameter, convex to umbonate, margin smooth, sometimes involute, tacky when moist, sometimes hygrophanous especially when frosted, almost uniformly colored, occasionally more bicolored, at center dark pinkish buff to dark olive buff or clay-buff to brownish olive, grayish brown or umber, at margin pinkish to grayish buff or clay-buff, occasionally pruinose ( givré), without any traces of veil. Lamellae clay buff, emarginate to adnate, maximum depth 3.5-5 mm, number of lamellae {L} 30-34, droplets often visible, occasionally absent or visible with × 10 lens, white fimbriate edge present. Stem 1.0-4.0 × 0.1-0.8 {median} × 0.1-1.0 {base} cm, stem Q (4-)4.8-14(-20), fairly strongly whitish fibrillose-flocculose, cylindrical to clavate, rarely bulbous, fibrillose, pruinose, floccose, particularly noticeable at apex. Context firm, stem interior stuffed, hollow with age, flesh discoloring from base at most very weakly. Smell raphanoid. Taste mild, occasionally weakly bitter or raphanoid. Spore deposit brownish olive.

Microscopic description.

Spores amygdaloid, occasionally limoniform, papillate, on ave. 11.0-13.0 × 6-7.5 µm, ave. Q = 1.6-1.9, yellow to brown, usually guttulate, weakly to distinctly ornamented (O2O3), perispore not or somewhat loosening (P0P1 (P2)), indistinctly to weakly dextrinoid (D1D2). Basidia 27-40 × 7-11 µm, ave. Q = 2.8-4.1, mostly four-spored. Cheilocystidia capitate-stipitate, clavate-stipitate or occasionally clavate-lageniform, occasionally with characteristic apical or median wall thickening, sometimes geniculate or septate, on ave. 40-60 × 8-11.0 (apex) × 3.5-5 (middle) × 3-6 (base) µm, ratios A/M = 1.87-2.67, A/B = 1.81-3.02, B/M = 0.84-1.24. Epicutis an ixocutis, 40-100 µm thick (measured from exsiccata), maximum hyphae width 6-6.5 µm, some encrusted, trama elements beneath subcutis cylindrical, sausage-shaped, up to 30 µm wide. Caulocystidia similar to cheilocystidia but larger, up to 100 µm long.

Collections examined.

S-Greenland: Qassiarsuk, Tasiusaq, 61.15°N, 45.52°W, 21 Jul 1984, T. Læssøe (TL 84.041, C-F-119793), 25 m. W-Greenland: Qeqertarsuaq/Disko, Godhavn, Østerlien, 69.25°N, 53.54°W, 30 Jul 1986, T. Borgen (TB86.085, C-F-104302), 40 m, with Salix glauca in copse.

Distribution.

Only two collections, from southwestern Greenland. Although described 50 years ago, H. minus is still only known from a few collections in Iceland and Svalbard, and from the French, Italian and Swiss Alps at 2200-2700 m. The Icelandic localities are from the upper boreal zone, but close to the oroboreal zone, which is equivalent to the alpine zone ( Rivas-Martinez et al. 2004). The Svalbard localities are in the High Arctic, whereas the two Greenland collections are both from the Low Arctic zone. This is a truly arctic-alpine species. It is new to North America and these are the first records outside Europe.

Habitat and ecology.

Two collections, one recorded with Salix glauca . Beker et al. (2016) list S. herbacea , S. reticulata , S. retusa and Dryas octopetala as hosts from arctic and alpine sites in Europe.

Hebeloma subsect. Clepsydroida Beker & U. Eberh.; Fungal Biol. 120: 82, 2015 ( “2016”).

Cheilocystidia distinctly broadened at apex, base ± swollen, wall often thickened at the middle. Lamellae edge often with exuded drops, but sometimes dried away.

Figures

Figure 28. Hebeloma minus A HJB 11945 (from Svalbard), photo H. K. J. Beker, reproduced by kind permission from Beker et al. (2016) B distribution of cited collections C spores x 1600 and D cheilocystidia x 1000 of TB 86.085 in Melzer's reagent. Scale bars: 5 µm; microphotographs H. K. J. Beker.