Hebeloma pubescens Beker & U. Eberh.; Beker, Eberhardt & Vesterholt, Fungi Europ. (Alassio) 14: 173, 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 pubescens Beker & U. Eberh.; Beker, Eberhardt & Vesterholt, Fungi Europ. (Alassio) 14: 173, 2016. Fig. 19

Macroscopic description.

Cap 1.2-2.4 cm in diameter, convex to umbonate, sometimes papillate, margin smooth, tacky when moist, not hygrophanous, unicolored or variably bicolored, at center grayish brown to yellowish brown or umber, tomentose, usually covered, particularly at the margin, with soft hairs, at margin dark grayish buff, sometimes with remains of universal veil, partial veil present. Lamellae light brown, later slightly darker, emarginate, maximum depth 2.5-5 mm, number of lamellae {L} 25-32, droplets absent, white fimbriate edge weakly present. Stem 1.1-4.6 × 0.2-0.4 cm, whitish pale floccose in apex, downwards lengthily fibrillose, sordid brown or very pale ochraceous, cylindrical, stem Q (3.7-)4.8-8.3(-9.7), fibrillose. Context firm, stem interior stuffed, later hollow, flesh usually discoloring from base. Smell raphanoid, sometimes strongly. Taste mild. Spore deposit brownish olive.

Microscopic description.

Spores ellipsoid, sometimes ovoid, pale yellow to yellow brown, guttulate, sometimes weakly, on ave. 10.0-12.0 × 6.0-6.5 µm, ave. Q = 1.5-1.8, almost smooth or weakly ornamented (O1O2), perispore not loosening (P0), indextrinoid (D0). Basidia 28-33(-37) × 8-9 µm, ave. Q = 3.1-4.4, mostly four-spored. Cheilocystidia lageniform or ventricose, occasionally with characteristic basal or median wall thickening, septate, on ave. 38-45 × 4.5-6 (apex) × 4.5-6 (middle) × 8-10.5 (base) µm, ratios A/M = 1.02-1.10, A/B = 0.51-0.73, B/M = 1.52-2.10. Epicutis an ixocutis, 90-100 µm thick (measured from exsiccata), maximum hyphae width 6 µm, sometimes encrusted, trama elements beneath subcutis isodiametric up to 15 µm wide. Caulocystidia similar to cheilocystidia but less ventricose, up to 120 µm long.

Collections examined.

W-Greenland: Disko, Kangaarsuk, Fortune Bay, 69.25°N, 53.54°W, 3 Aug 1986, T. Borgen (TB86.128, C-F-5089), 0 m, with Salix sp. N-Greenland: Zackenberg, W of Kærelv, 74.5°N, 21°W, 13 Aug 1999, T. Borgen (TB99.305, C-F-119753), 50 m, with Dryas sp. in scrubland. Zackenberg, W of Zackenberg River, 74.5°N, 21°W, 5 Aug 1999, T. Borgen (TB99.194, C-F-119750), 50 m, with Dryas sp. and Salix arctica in scrubland.

Distribution.

Recently described from three records on Svalbard ( Beker et al. 2016). The Greenland records are all north of 69° and, together with the type from 78°N, establish this as one of the few agarics, which appear only to occur in the High Arctic zone. The Greenland records are new to North America and the first outside Europe. High Arctic.

Habitat and ecology.

Three collections, two with Dryas and one with Salix sp. The collections from Zackenberg were on rich soil. Beker et al. (2016) described it from Svalbard, where the host was Salix polaris .

Figures

Figure 19. Hebeloma pubescens A TB 99.194, photograph T. Borgen B distribution of cited collections; C spores x 1600 and D cheilocystidia x 1000 of TB 99.194 in Melzer's reagent. Scale bars: 5 µm; microphotographs H. K. J. Beker.