Hebeloma spetsbergense Beker & U. Eberh., Fungi Europaei 14 (Lomazzo): 180 (2016)

Cripps, Cathy L., Eberhardt, Ursula, Schuetz, Nicole, Beker, Henry J., Vera S. Evenson, & Horak, Egon, 2019, The genus Hebeloma in the Rocky Mountain Alpine Zone, MycoKeys 46, pp. 1-54 : 39-41

16. Hebeloma spetsbergense Beker & U. Eberh., Fungi Europaei 14 (Lomazzo): 180 (2016) Figures 6A, 22

Etymology.

Originally found in Svalbard.

Description.

Cortina present. Pileus 10-25 mm in diameter, shallow convex, almost applanate with indistinct umbo or not, smooth, tacky to dry, brown in center, outwards paler brown or more cinnamon, with white edge, not hygrophanous; margin turned down in young specimens, entire. Lamellae attached, adnexed, medium close, L = 26-30, pale cream to milk coffee, to brown; edges indistinct fimbriate. Stipe long and thin, 20-40 × 2-3 mm, equal, cream at apex to dark brown at base, fibrils at apex, and below silky-smooth with longitundinal fibrils. Context cream and brown to black in lower part. Odor raphanoid. Exsiccata: pileus brown, darker brown in center; lamellae reddish brown; stipe thin, cream but darkening at base.

Basidiospores yellow brown, amygdaliform, without a large snout, apiculate, not guttulate, finely verrucose (O1, O2), distinctly and sometimes strongly dextri noid (D2, D3), no loosening perispore observed (P0), 11-14 × 7-8.5 µm, on average 12.5 × 7.6 µm, Q = 1.65. Basidia 28-35 × 8-10 µm, clavate, mostly four-spored. Cheilocystidia lageniform, with long cylindrical neck, 30-80 × 4-7 µm at apex, 4-5.5 µm in middle, and 7-10.5 µm at base. Pleurocystidia absent. Epicutis thickness 30-35 µm, with no encrusted hyphae recorded.

Rocky Mountain ecology.

In alpine habitats in Colorado, in moss near Salix species.

Rocky Mountain specimens examined.

U.S.A. COLORADO: San Juan County, San Juan Mountains, Mineral Basin, 31 July 2002, CLC1879 (MONT), C. Cripps. Clear Creek County, Denver Mountain Park, Summit Lake, 3911 m, in Salix arctica and S. glauca , 20 Aug 2013, DBG-F-027678, L. Gillman.

Discussion.

According to Beker et al. (2018), H. spetsbergense cannot be distinguished from similar species by ITS. The two RM collections (Fig. 6A) differ by 4 [0] bp, the variation of H. spetsbergense within the sample (7 sequences) is 0-5 [0-2] bp. Hebeloma nigellum is the most similar species occurring in the same habitat and, within this sample, differs in its ITS by 1-8 [0-3] bp from H. spetsbergense . Morphologically H. spetsbergense is similar to H. hygrophilum and H. nigellum , but its spores appear to be larger. Previously this species was only known from Svalbard ( Beker et al. 2016, 2018), and we report it here from North America for the first time. In Svalbard, it was found with Salix Polaris near sea level at a latitude of 78°N. In Colorado, it is reported at elevations of 3700-3800 m and latitudes from 36-38°N, and there is a distance between localities of 6500 km, greatly extending its disjunct range. It remains to be seen, if it also occurs in other arctic and alpine habitats.

With the persistent presence of a cortina and the lageniform or ventricose cheilocystidia, this taxon clearly belongs in H. sect. Hebeloma . The rather strongly dextrinoid amygdaloid spores, less than 14 µm long but more than 7.5 µm wide, distinguish this taxon from the other alpine-arctic species of this section.