Hebeloma hiemale Bres., Fung. Trident. 2: 52 (1898)

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 : 17-20

4. Hebeloma hiemale Bres., Fung. Trident. 2: 52 (1898) Figures 4B, 10, 23 (4)

Etymology.

From hiemalis, winter or wintry, presumably to denote the production of basidiomes in colder seasons or habitats

Description.

Cortina absent. Pileus 15-35 mm in diameter, slightly conic-convex or domed-convex, smooth, greasy, pinkish buff, yellowish buff, to pale cream at the margin, with uniform coloration, somewhat hoary, with or without a white rim a few mm wide at margin; margin turned down or rolled in, then wavy. Lamellae narrowly attached, emarginate, somewhat crowded, L = 48-60 plus lamellulae, white to pale milk coffee, pale brown, wood brown; edges white floccose, with drops of liquid. Stipe 20-45 × 5-12 mm, equal, slightly clavate towards the base, whitish cream, totally pruinose (big floccules) for most of length and smoother below. Context white to watery cream, firm. Odor raphanoid, faint. Exsiccate: pileus yellowish brown, not distinctly two-toned; lamellae brown with white edges; stipe white and slimmer than for H. alpinum .

Basidiospores yellowish brown, some coloring slightly brown in Melzer’s, fat-bellied amygdaliform, limoniform, with short snout, apiculate, distinctly ornamented (O2), a few with slightly loosening perispore (P0,P1), rarely guttulate, with thickish wall, slightly dextrinoid (D1, rarely D2), 10-12 × 6-7 µm, on average, 11.1 × 6.8 µm, Q = 1.64. Basidia 25-35 × 7-9, most four-spored, maybe a few two-spored, occasionally with long sterigmata (-5 µm). Cheilocystidia long, gently clavate, clavate-lageniform, some with septa, 35-75 µm long, at apex 6-9 µm, in middle 4-6 µm, at base 4.5-9 µm, thickening sometimes observed in the middle. Pleurocystidia absent. Epicutis thickness 60-200 µm, with some encrusted hyphae.

Rocky Mountain ecology.

In the alpine zone with dwarf willows, Dryas and Betula , confirmed from Colorado, Montana, and Wyoming.

Rocky Mountain specimens examined.

U.S.A. COLORADO: Summit County, Loveland Pass, 3750 m, with Salix in scrubland, 7 Aug 1999, ZT8072 (ETH), E. Horak; 15 Aug 1997, 3655 m, with Salix , DBG-F-019162, B. Rognerud; 21 Aug 2003, with Salix sp., DBG-F-021418, H. Miller; 20 Aug 1999, 3597 m, with Betula , DBG-F-020440, O.K. Miller; 22 Aug 1999, 3655 m, with Salix sp., DBG-F-020437, O.K. Miller; 16 Aug 1997, 3749 m, with Salix sp., DBG-F-019241, S. Trudell; 19 Aug 1999, 3620 m, DBG-F-021194, V.S. Evenson; 20 Aug 1999, 3620 m, with Salix sp., DBG-F-20431, V.S. Evenson; 20 Aug 1999, 3571 m, with Betula nana , DBG-F-020433, V.S. Evenson; 24 Aug 1999, 3620 m, with Salix sp., DBG-F-019597, N. Smith Weber; Clear Creek County, Mount Goliath, 3658 m, with Salix , 1 Sept 1999, DBG-F-020551, V.S. Evenson; 1 Sept 1999, 3810 m, DBG-F-020550, V.S. Evenson; Boulder County, West of Caribou townsite, 10 July 1988, DBG-F-016104, V.S. Evenson. Sawatch Range, Independence Pass, 13 Aug 2001, 3759 m, with Dryas octopetala and S. reticulata , ZT9828, E. Horak. San Juan County, San Juan Mountains, Mineral Basin, 3835 m, with Salix arctica , 7 Aug 2001, CLC1668 (MONT), C. Cripps. MONTANA: Carbon County, Beartooth Plateau (at the stateline with WY), 3100 m near S. reticulata , 19 July 2001, CLC1574 (MONT), C. Cripps; site 2 at the stateline MT/WY, with S. reticulata 14 Aug 2014, CLC3094 (MONT), C. Cripps; Quad Creek, 3004 m, with S. reticulata and Persicaria vivipara , 8 Aug 2008, HJB12457, M. Nauta; site 1 in Dryas , 11 Aug 2017, CLC3533 (MONT), C. Cripps; with S. planifolia and S. glauca , 17 Aug, 2017, CLC3574 (MONT), C. Cripps; with Salix planifolia , 17 Aug 2017, CLC3575 (MONT), C. Cripps. WYOMING: Park County, Highline Trail, 3200 m, with Dryas octopetala and S. reticulata , 8 Aug 2008, ZT6417 (ETH), E. Horak.

Discussion.

An ITS tree including H. hiemale is given by Eberhardt et al. (2016); the respective network is shown in Figure 4B. The RM dataset includes ITS sequences from 22 collections. These were matched by the same number of sequences from the FE dataset. Hebeloma hiemale ITS sequences were shown to form a well-supported monophylum in ML results presented in earlier studies ( Beker et al. 2016; Eberhardt et al. 2016). Beker et al. (2010) showed that it is a species with a relatively high number of different ITS variants. The disparity between variants is mostly caused by gaps and SNPs (single-nucleotide polymorphisms). The number of differences between any pair of sequences of the presented H. hiemale data set is 0-9 [0-2] bp, within the RM sequences 0-8 [0] bp.

This species is widespread across Europe occurring from the subalpine to the alpine, in lowland dunes, shrublands, gardens, and parks; it occurs with a wide array of deciduous and coniferous trees and this includes a number of willow species, including dwarf Salix . Confirmed arctic-alpine reports include those from Canada, Greenland, Iceland, Scandinavia, and Svalbard with Salix herbacea and S. polaris as well as Dryas and Persicaria ( Beker et al. 2016). Here it is confirmed with S. reticulata . Hebeloma hiemale has rarely been reported from North America in either subalpine or alpine habitats ( Beker et al. 2010), but many collections previously labeled H. alpinum are now confirmed as H. hiemale .

This species looks like a small version of Hebeloma crustuliniforme but usually has more color in the pileus, particularly at the center. It has cheilocystidia that are generally swollen in the lower half, giving an hourglass appearance. The spores are verrucose, more warty than those of H. alpinum , but less so than the spores of H. vaccinum . There was some ambiguity around the delineation of H. hiemale , which was ultimately resolved with selection of an epitype ( Beker et al. 2010; Eberhardt et al. 2015a).