Hebeloma excedens (Peck) Sacc.; Syll. fung. (Abellini) 5: 806, 1887.

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 excedens (Peck) Sacc.; Syll. fung. (Abellini) 5: 806, 1887. Fig. 11

Macroscopic description.

Cap 1.0-4.0 cm in diameter, shallowly convex, campanulate, then almost applanate, broadly umbonate or not, viscid or greasy, with hygrophanous spots, cinnamon to orange-brown or dark brick in center and pale brown on most of the cap, almost unicolored, with or without velar remnants at margin, or with whitish rim, margin originally described as extending beyond the lamellae, thin-fleshed, universal veil sometimes visible on margin edge, partial veil present. Lamellae sinuate, subdecurrent, narrow, becoming broader and eroded, 3.5-5.5 mm broad, without droplets, very pale, cream with pinkish buff tint, number of lamellae {L} 36-48. Stem 1.5-5.0 × 0.2-0.4 cm, equal, slightly curved, pale cream, silky, pruinose above ring zone, dingier to dark brown below, but still pale with golden brown fibrils in zones, blackening towards base, tough, rubbery. Context whitish in cap and stem apex and yellowish brown in lower stem down to blackish at base. Smell raphanoid, rarely odorless. Spore deposit brownish olive.

Microscopic description.

Spores ellipsoid, a few slightly ovoid, not papillate, 8.5-10.5 × 5-6 µm, ave. Q 1.5-2.0, very weakly ornamented (O1O2), perispore not noticeably loosening (P0), indistinctly dextrinoid (D0D1), pale yellow, rarely yellow brown, ± guttulate. Basidia 20-33 × 6-8 µm, ave. Q = 3.2-4, clavate, mostly four-spored. Cheilocystidia usually lageniform or ventricose, sometimes cylindrical, occasionally geniculate or septate, subcapitate, on ave. 30-55 × 4-6 (apex) × 4-5 (middle) × 7-9 (base) µm, ratios A/M = 0.96-1.23, A/B = 0.60-0.71, B/M = 1.60-1.82. Epicutis an ixocutis, up to 90 µm thick (measured from exsiccata), ixocutis maximum hyphae width up to 6 µm, hyphae rarely encrusted, shape of trama elements beneath subcutis ellipsoid. Caulocystidia similar to cheilocystidia, but usually larger.

Collections examined.

S-Greenland: Paamiut, 62.01°N, 49.4°W, 23 Aug 1985, T. Borgen (TB85.238, C-F-5073), 10 m, with Salix glauca . W-Greenland: Kangerlussuaq near the Ice cap, 67.10°N, 50.23°W, 12 Aug 2000, A-M. Larsen, T. Borgen (TB00.086, C-F-103517), 40 m, with Salix glauca in a copse. Sisimiut, 1 km N of the village, 66.94°N, 53.67°W, 19 Aug 2000, E. Ohenoja (EO19.8.00.20, OULU F050653), 0 m, in heathland.

Distribution.

Known from three localities in southwestern Greenland. Originally described from New York State under Pinus and widespread across North America ( Cripps et al. 2019). Similar to H. mesophaeum and therefore likely to be confused and overlooked. Cripps et al. also describe recent records from alpine Rocky Mountains in Colorado and Montana.

Habitat and ecology.

Three collections, two of them with Salix glauca . In the Rocky Mountains, S. planifolia was the dominant host ( Cripps et al. 2019). Two of the localities are on acid soil.

Figures

Figure 11. Hebeloma excedens A TB 85.238, photograph T. Borgen B distribution of cited collections C spores x 1600 and D cheilocystidia x 1000 of TB 85.238 in Melzer's reagent. Scale bars: 5 µm; microphotographs H. K. J. Beker.