A survey of Hebeloma (Hymenogastraceae) in Greenland Author Eberhardt, Ursula https://orcid.org/0000-0003-1221-7074 Staatliches Museum fuer Naturkunde Stuttgart, Rosenstein 1, D- 70191 Stuttgart, Germany ursula.eberhardt@smns-bw.de Author Beker, Henry J. https://orcid.org/0000-0001-9620-1701 Rue Pere de Deken 19, B- 1040 Bruxelles, Belgium & Royal Holloway College, University of London, Egham, UK & Plantentuin Meise, Nieuwelaan 38, B- 1860 Meise, Belgium Author Borgen, Torbjorn https://orcid.org/0000-0003-1174-9466 Sensommervej 142, 8600 Silkeborg, Denmark Author Knudsen, Henning Hauchsvej 15, 1825 Frederiksberg, Denmark Author Schuetz, Nicole Staatliches Museum fuer Naturkunde Stuttgart, Rosenstein 1, D- 70191 Stuttgart, Germany Author Elborne, Steen A. Frederik VII's Vej 29, 3450 Allerod, Denmark text MycoKeys 2021 2021-04-19 79 17 118 http://dx.doi.org/10.3897/mycokeys.79.63363 journal article http://dx.doi.org/10.3897/mycokeys.79.63363 1314-4049-79-17 CEDC3742C169540583072E7995018533 Hebeloma louiseae Beker, Vesterh. & U. Eberh.; Eberhardt, Beker & Vesterholt, Persoonia 35: 127, 2015. Fig. 27 Macroscopic description. Cap 0.7-2.2 cm in diameter, convex to broadly umbonate, margin smooth to crenulate, tacky when moist, not hygrophanous, uniformly colored or indistinctly bicolored, at center clay-buff to dark olive buff, margin very thin, grayish pink or central color extending to margin, with no traces of veil. Lamellae initially pale, later sordid clay-brown, emarginate, maximum depth 2 mm, number of lamellae {L} 28-40, droplets often absent but occasionally visible even with the naked eye, white fimbriate edge present. Stem 0.8-2.5 x 0.2-0.3 {median} x 0.1-0.3 {base} cm, initially pale, later sordid brownish, cylindrical to clavate, occasionally tapering, stem Q (4-)4.6-7.6(-9.2), pruinose to slightly fibrillose. Context firm, interior stuffed, flesh discoloring weakly from base. Smell absent or raphanoid. Taste not recorded. Spore deposit grayish brown. Figure 27. Hebeloma louiseae A SAE-2017.125, photograph S.A. Elborne B distribution of cited collections C spores x 1600 and D cheilocystidia x 1000 of HK17.128A.146 in Melzer's reagent. Scale bars: 5 µm ; microphotographs H.K.J. Beker. Microscopic description. Spores amygdaloid, limoniform, weakly to strongly papillate, on ave. 12.0-13.0 x 7.0-7.5 µm , ave. Q = 1.6-1.8, yellow brown to brown, guttulate, almost smooth to weakly ornamented (O1O2), perispore not loosening (P0), indextrinoid to indistinctly dextrinoid (D0D1 (D2)). Basidia 24-56 x 6-12 µm , ave. Q = 3.2-4.6, mostly four-spored. Cheilocystidia clavate-stipitate, occasionally spathulate-stipitate or capitate-stipitate or clavate-lageniform, occasionally with characteristic apical wall thickening, occasionally bifurcate, septate or sinuate, on ave. 42-59 x 6-11 (apex) x 4.0-5.5 (middle) x 3.5-6.0 (base) µm , ratios A/M = 1.48-2.51, A/B = 1.99-2.92, B/M = 0.81-1.24. Epicutis an ixocutis, up to 100 µm thick (measured from exsiccata), maximum hyphae width 6 µm , sometimes encrusted, trama elements beneath subcutis cylindrical, sausage-shaped. Caulocystidia similar to cheilocystidia, up to 75 µm long. Collections examined. W-Greenland : Kangerlussuaq, c. 2 km W of the Airport, 67.06°N , 50.68°W , 10 Aug 2000, A-M. Larsen, T. Borgen (TB00.061, C-F-103518), 50 m, with Salix glauca in ditch. Kangerlussuaq, Sandflugtsdalen, 67.06°N , 50.42°W , 25 Aug 2016, S.A. Elborne (SAE-2016.197-GR, C-F-106747), 110 m, with Salix glauca in dune slack. E-Greenland : Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gaseelv valley, 70.76°N , 22.65°W , 6 Aug 2017, H. Knudsen (HK17.128, C-F-105029), 40 m. Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gaseelv valley, 70.76°N , 22.65°W , 6 Aug 2017, S.A. Elborne (SAE-2017.125A-GR, C-F-106763), 40 m, with Salix arctica at riverside. Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gaseelv valley, 70.77°N , 22.69°W , 6 Aug 2017, S.A. Elborne (SAE-2017.125B-GR, C-F-106763), 15 m, with Salix arctica at riverside. Distribution. Recently described from Svalbard ( Beker et al. 2016 ). The five Greenland collections all occurred north of 67°N and thus provide evidence that H. louiseae is a species of the High Arctic zone. It has not yet been recorded in alpine regions. The Greenland collections are the first from North America and the first outside Europe. Habitat and ecology. Five collections, with Salix glauca and S. arctica in calcareous soil and seemingly moist localities. From Svalbard it was recorded with S. polaris ( Beker et al. 2016 ). Notes. Hebeloma louiseae is easily recognized among the arctic Hebeloma species by the small basidiomes, the relatively few lamellae and the large basidia, although not present in every collection.