Hebeloma vaccinum Romagn.; Bull. trimest. Soc. mycol. Fr. 81: 333, 1965.

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 vaccinum Romagn.; Bull. trimest. Soc. mycol. Fr. 81: 333, 1965. Fig. 30

Macroscopic description.

Cap 0.9-6.1 cm in diameter, convex, later umbonate, margin usually involute when young, sometimes crenulate or scalloped, tacky when moist, not hygrophanous, usually bicolored, but sometimes almost unicolored, at center from clay-buff to yellowish brown and dark olive buff to dark brick or rust brown, at margin cream to gray-buff to clay-buff, pale and very thin, without any traces of veil. Lamellae light, then sordid gray-brown, adnexed to emarginate, maximum depth 2-6 mm, number of lamellae {L} 32-60, droplets visible with naked eye or sometimes with × 10 lens, white fimbriate edge present. Stem 0.9-5.5 × 0.3-1.3 {median} × 0.3-1.3 {base} cm, stem Q (2.2-)2.7-9(-13.3), white flocculose on pale brown ground, downwards watery gray-brown, later watery ochre-brown, not darker at base, base cylindrical to clavate or bulbous, sometimes with encrusted sand, pruinose to floccose, particularly at apex. Context firm, stem interior stuffed, later hollow, sometimes with superior wick, flesh not discoloring from base. Smell raphanoid, sometimes of cocoa. Taste sometimes raphanoid, sometimes bitter. Spore color brownish olive to sepia.

Microscopic description.

Spores mainly amygdaloid, sometimes fusoid or limoniform, papillate, on ave. 12.0-14.5 × 6.5-8.0 µm, ave. Q = 1.6-2.0, yellow-brown to brown, sometimes guttulate, distinctly to fairly strongly ornamented ((O2) O3O4), perispore somewhat to distinctly loosening ((P0) P1P2), weakly to rather strongly dextrinoid (D2D3). Basidia 27-39 (-42) × 7-12 µm, ave. Q = 3-4.5, mostly four-spored. Cheilocystidia clavate-lageniform, capitate-lageniform, sometimes clavate-stipitate or capitate-stipitate or ventricose, occasionally characteristically with apical or median wall thickening, sometimes geniculate, septate or sinuate, on ave. 41-64 × 6-8 (apex) × 3-5 (middle) × 4.5-8 (base) µm, ratios A/M = 1.43-2.31, A/B = 0.84-1.53, B/M = 1.28-1.92. Epicutis and ixocutis, 40-125 µm thick (measured from exsiccata), maximum hyphae width 5-6.5 µm, sometimes encrusted, trama elements beneath subcutis sausage-shaped, occasionally spherical up to 16 µm wide. Caulocystidia similar to cheilocystidia, up to 90 µm long, often with many septa.

Collections examined.

S-Greenland: Narsarsuaq, 61.08°N, 45.26°W, 7 Aug 1985, T. Borgen (TB85.045, C-F-103477), 150 m, with Dryas integrifolia in heathland. Narsarsuaq, Hospitalsdalen, 61.17°N, 45.41°W, 1 Aug 1992, E. Rald (ER 92.038, C-F-104308), 60 m, with Salix glauca and Betula glandulosa . Narsarsuaq, 61.17°N, 45.41°W, 17 Aug 2015, H. Knudsen (HK15.069, C-F-8222), 60 m, with Salix glauca and Betula pubescens at pathside. Qassiarsuk, Tasiusaq, 61.15°N, 45.52°W, 19 Aug 1992, E. Rald (ER 92.323, C-F-104311), 25 m. Tasiusaq, 61.14°N, 45.63°W, 28 Jul 1993, E. Rald (ER 93.022, C-F-104320), 20 m, with Salix glauca in fenland. N-Greenland: Zackenberg, Aucellabjerg, 74.5°N, 21°W, 20. Aug. 2006, T. Borgen (TB06.246, C-F-119780), 300 m, with Salix arctica and Bistorta vivipara in scrubland. Zackenberg, just E of the station, 74.5°N, 21°W, 26 Jul 1999, T. Borgen (TB99.109, C-F-119755), 40 m, with Dryas sp. and Salix sp. in scrubland. Zackenberg, just S of the Field Station, 74.48°N, 20.76°W, 19 Jul 1999, T. Borgen (TB99.008, C-F-119804), 30 m, with Dryas sp. and Bistorta vivipara . E-Greenland: Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gåseelv valley, 70.76°N, 22.65°W, 8 Aug 2017, T. Borgen (TB17C.073, C-F-106778), 40 m, in heathland. Jameson Land, Nerlerit Inaat/Constable Pynt, Hareelv, 70.71°N, 22.69°W, 10 Aug 2017, S.A. Elborne (SAE-2017.194-GR, C-F-106767), 100 m, with Salix arctica in tundra. Jameson Land, Nerlerit Inaat/Constable Pynt, Primulaelv, 70.74°N, 22.67°W, 1 Aug 2017, H. Knudsen (HK17.022B, C-F-104911), 180 m. Jameson Land, Nerlerit Inaat/Constable Pynt, Primulaelv, 70.74°N, 22.67°W, 1 Aug 2017, H. Knudsen (HK17.021, C-F-104909), 180 m. Jameson Land, Nerlerit Inaat/Constable Pynt, Primulaelv, 70.74°N, 22.67°W, 1 Aug 2017, H. Knudsen (HK17.022A, C-F-104910), 180 m.

Distribution.

Widely distributed in Greenland and apparently common in the localities where it was found; missing in western Greenland. It is widely distributed in the Temperate zone in Europe ( Beker et al. 2016) with a few records in subarctic areas in Sweden ( Härjedalen) and the Oroboreal zone in Iceland (Egilsstadir, 65°N). The Greenland collections from Zackenberg (74.5°N) are the northernmost recorded, to date. Hebeloma vaccinum was recently recorded from the alpine Rocky Mountains ( Cripps et al. 2019), but these Greenland records are the first from arctic North America.

Habitat and ecology.

Thirteen collections, all from calcareous or mineral rich areas. Hosts are Dryas , Salix glauca and S. arctica . Beker et al. (2016) concluded that the Salicaceae ( Salix and Populus ) are the host family for this species, with S. repens L. as the most often recorded host in Europe, but also S. lanata L.

Hebeloma subsect. Hiemalia Quadr.; Doc. mycol. 14: 30, 1985 ( “1984”).

Cheilocystidia distinctly broadened at apex, base ± swollen, wall often thickened at the middle. Spores with a majority that are weakly ornamented (O2) and the perispore which is not consistently or distinctly loosening (rarely P2 and never P3) and the pileus color which always has brown or buff tones at least in the center.

Figures

Figure 30. Hebeloma vaccinum A SAE- 2017.194, photograph S. A. Elborne B distribution of cited collections C spores x 1600 and D cheilocystidia x 1000 of SAE- 2017.194 in Melzer's reagent. Scale bars: 5 µm; microphotographs H. K. J. Beker.