Hebeloma nigellum 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 nigellum Bruchet; Bull. mens. Soc. linn. Lyon 39(6(Suppl.)): 126, 1970. Fig. 17

Macroscopic description.

Cap 0.7-3.4 cm in diameter, convex to umbonate, occasionally papillate, margin involute, tacky when moist, unicolored or usually bicolored, at center umber to dark brick or snuff brown, at margin cream to pinkish buff, occasionally with remains of universal veil, partial veil present. Lamellae at maturity brownish clay, adnate to emarginate, maximum depth 2.5-6 mm, number of lamellae {L} 22-36, droplets absent, white fimbriate edge present, sometimes weakly. Stem 1.4-5.0 × 0.15-0.4 cm, whitish pruinose at apex, initially whitish lengthily fibrillose, downward, sordid brown, cylindrical, stem Q (6.5-)7.5-12.5(-18.7), fibrillose, pruinose to floccose at apex. Context firm, stem interior stuffed later hollow, flesh discoloring from base, sometimes very strongly. Smell usually raphanoid, sometimes none. Taste bitter, raphanoid. Spore deposit umber.

Microscopic description.

Spores mainly amygdaloid, sometimes ellipsoid to ovoid, on ave. 11.0-13.5 × 7.0-7.5 µm, ave. Q = 1.5-1.9, yellow through yellow brown to brown, guttulation variable, almost smooth to slightly ornamented (O1O2), perispore not or very slightly loosening (P0 (P1)), rather strongly dextrinoid ((D2) D3). Basidia 25-39(-45) × 7-10(-11) µm, ave. Q = 3.1-3.9, mostly four-spored. Cheilocystidia usually lageniform, ventricose, occasionally cylindrical, occasionally with characteristic apical wall thickening, geniculate or septate (sometimes clamped), 44-65 × 4.5-6.5 (apex) × 4-5.5 (middle) × 6.5-11 (base) µm, ratios A/M = 0.92-1.41, A/B = 0.45-0.89, B/M = 1.45-2.3. Epicutis an ixocutis, 40-75 µm thick (measured from exsiccata), maximum hyphae width 5-6.5 µm, sometimes encrusted, trama elements beneath subcutis ellipsoid, polygonal, sausage-shaped up to 15 µm wide. Caulocystidia rather irregular, similar to cheilocystidia, up to 140 µm long.

Collections examined.

S-Greenland: Kangilinnguit, bottom of Laksebund, 61.25°N, 48.08°W, 16 Aug 2018, H. Knudsen (HK18.199, C-F-111110), 100 m, with Alnus alnobetulae in scrubland. Nanortalik municipality, Qinngua valley, 60.14°N, 45°W, 6 Aug 1991, T. Borgen (TB91.080, C-F-103490), 250 m, with Salix glauca in copse. Paamiut, 62.01°N, 49.4°W, 31 Aug 1986, T. Borgen (TB86.276, C-F-103572), 10 m. Paamiut, 62.01°N, 49.4°W, 14 Aug 1990, T. Borgen (TB90.035, C-F-103479), 10 m. Paamiut, 62.01°N, 49.4°W, 1 Sep 1990, T. Borgen (TB90.073, C-F-103541), 10 m, with Salix arctophila along riverside. Paamiut, Kangilineq, Kvaneøen, 61.95°N, 49.47°W, 26 Aug 1984, T. Borgen (TB84.183, C-F-103468), 10 m, with Salix arctophila . Paamiut, Kangilineq/ Kvaneøen, 61.57°N, 49.28°W, 25 Aug 1985, T. Borgen (TB85.249, C-F-103529), with Salix . Paamiut, Kangilineq/ Kvaneøen, 61.99°N, 49.66°W, 26 Aug 1990, T. Borgen (TB90.056, C-F-103542), 15 m, with Salix arctophila in fenland. W-Greenland: Disko, N end of Blæsedalen, 69.5°N, 53.32°W, 25 Jul 1986, T. Borgen (TB86.052, C-F-119739), 300 m, with Salix herbacea in snowbed. Kangerlussuaq, Ammaloortup Nunaa W of Lake Ferguson, 66.99°N, 50.61°W, 8 Aug 2016, H. Knudsen (TB16.086G, C-F-103583), 275 m, with Salix glauca , Betula nana and Sphagnum along streamside. Kangerlussuaq, Kløftsøerne, 67.06°N, 50.68°W, 13 Aug 2016, H. Knudsen (HK16.110, C-F-104140), 500 m, with Salix glauca . Kangerlussuaq, Lake Ferguson, Tasersuatsiaq, 66.97°N, 50.70°W, 22 Aug 2016, S.A. Elborne (SAE-2016.131-GR, C-F-106743), 100 m, with Salix glauca in copse. Kangerlussuaq, NE facing slopes along Lake Ferguson, 66.99°N, 50.61°W, 8 Aug 2016, H. Knudsen (HK16.033, C-F-104063), 300 m, with Salix glauca in riverbed. Kangerlussuaq, outlet of Lake Ferguson, 66.99°N, 50.61°W, 6 Aug 2016, T. Borgen (TB16.060G, C-F-103580), 275 m, with Salix glauca in scrubland. Kangerlussuaq, W Bridge near Ice cap, 67.09°N, 50.23°W, 2 Aug 2016, T. Borgen (TB16.035G, C-F-103577), 50 m, with Salix glauca at lakeside. NW of Nasaassaq, E-valley, E of Sisimiut, 66.93°N, 53.61°W, 18 Aug 2000, E. Horak (ZT9139, ZT9139), 50 m, with Betula nana , Salix glauca and Salix herbacea . Qeqertarsuaq/Disko, Godhavn area, 69.65°N, 53.32°W, 26 Jul 1986, T. Borgen (TB86.065, C-F-119791), 450 m. Sisimiut, 1 km north of the village, 66.94°N, 53.67°W, 19 Aug 2000, E. Ohenoja (EO19.8.00.20, OULU F050653), 0 m, in heathland. Sisimiut, in the E valley, 66.89°N, 52.86°W, 15 Aug 2016, H. Knudsen (HK16.133, C-F-104163), 0 m, with Salix herbacea . Sisimiut, Kællingehætten, 66.93°N, 53.59°W, 16 Aug 2016, H. Knudsen (HK16.165A, C-F-108402), 400 m. E-Greenland: Jameson Land, Constable Pynt, Draba Sibirica Elv, 71.15°N, 23.57°W, 28 Jul 1983, D. Boertmann (DB GR 83-80, C-F-119734), 0 m, with Salix arctica .

Distribution.

Hebeloma nigellum is common and widespread in Greenland and present in other parts of North America ( Cripps et al. 2019). It is widespread in temperate Europe, but more commonly in arctic-alpine areas ( Beker et al. 2016). Circumpolar.

Habitat and ecology.

Twenty-one collections, and where the host was specified, 15 were recorded with Salix ( S. glauca 8, S. arctophila 3, S. herbacea 3, S. arctica 1), and one recorded with Alnus alnobetulae ssp. crispa . The majority are from riversides, lakesides, fens and snowbeds, but also in humid places with S. arctophila . Most localities are on neutral ground, but it is found in acid localities as well. In the Rocky Mountains, it was recorded with Salix planifolia ( Cripps et al. 2019). From lowland Europe Beker et al. 2016 noted S. aurita and S. cinerea as hosts.

Figures

Figure 17. Hebeloma nigellum A HK 16.033, photograph H. Knudsen B distribution of cited collections C spores x 1600 and D cheilocystidia x 1000 of TB 85.249 in Melzer's reagent. Scale bars: 5 µm; microphotographs H. K. J. Beker.