Hebeloma velutipes Bruchet, Bull. Mens. Soc. Linn. Lyon 39 (6, suppl.): 127 (1970)

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 : 21-24

6. Hebeloma velutipes Bruchet, Bull. Mens. Soc. Linn. Lyon 39 (6, suppl.): 127 (1970) Figures 5, 12, 23 (6)

Etymology.

velutinus, for the velvety appearance of the stipe surface.

Description.

Cortina absent. Pileus 20-60 mm in diameter, convex, convex-domed, tacky to kidskin, smooth, not spotting, not hygrophanous, nearly unicolor, very pale buff, pale salmon buff, with hoary coating (pruinose); margin incurved but not involute, entire. Lamellae narrowly attached, sinuate or marginate, narrow to broad, slightly crowded, L = 50-75 plus lamellulae, white at first, then milk coffee color; edges white-floccose; beaded drops observed on some. Stipe (25 –)30– 60 × 7-15 mm, robust, equal and either narrowing or swollen at base up to 20 mm wide, slightly curved or not, pruinose or floccose in top half, longitudinally fibrous in lower half or more smooth. Context whitish, thick in pileus, firm in stipe, stuffed/hollow. Odor raphanoid. Exsiccate: largest of all species recorded; uniform pale buff pileus, lamellae, and stipe.

Basidiospore print deep Sayal brown. Basidiospores yellowish brown, amygdaliform, with a slight snout, apiculate, not guttulate, a bit rough (O1, O2), moderately dextrinoid (D2, D3), no obvious loosening perispore (P0), 10-12 × 6-7 µm, on average 10.4 × 6.6 µm, a few large spores (-18 × -7) present, Q = 1.57. Basidia 26-32 × 7.5-9 µm, clavate, four-spored. Cheilocystidia gently clavate, thin-walled, occasionally bifurcate at apex, 55-80 µm × 7-12 µm at apex, 5-8 µm in middle, 4-7 µm at base. Pleurocystida absent. Epicutis thickness 80-200 µm, with some encrusted hyphae.

Rocky Mountain alpine ecology.

In alpine situations, mostly reported with Dryas octopetala and also with Salix in Montana and Colorado.

Rocky Mountain specimens examined.

U.S.A. COLORADO: Gunnison County, Sawatch Range: Cumberland Pass, 3660 m, near Salix glauca but Dryas in vicinity, 4 Aug 2001, CLC1651 (MONT), C. Cripps; Cottonwood Pass, 3700, in pure Dryas octopetala , 4 Aug 2001, CLC1646 (MONT), 12 Aug 2001, CLC1725 (MONT), both C. Cripps. Summit County, Herman Gulch Trailhead, 3200 m, with Salix spp., 26 Aug 1983, DBG-F-005617, V.S. Evenson. MONTANA: Carbon County, Beartooth Plateau, site 1, 3000 m, in pure D. octopetala , 27 July 2004, CLC1980 (MONT), C. Cripps; N of East Summit, with Dryas and Salix reticulata , 30 July 1997, ZT6100 (ETH), E. Horak.

Discussion.

Grilli and co-workers (2016) showed that in ITS ML analyses H. velutipes falls into three unsupported clusters, i.e. one with H. incarnatulum , one with H. leucosarx , and one with H. subconcolor . The latter is discussed above; the former two species do not occur in the kind of habitats sampled in the Rocky Mountains ( Beker et al. 2016; Grilli et al. 2016). Hebeloma velutipes cannot be distinguished from these three species based on ITS, but it is distinct from all other species treated in Beker et al. (2016). The reason for the intraspecific variation observed in H. velutipes has already been shown by Aanen et al. (2001), namely that H. velutipes possesses ITS alleles that differ greatly. In the Rocky Mountains, representatives of two of the clusters were found, the H. leucosarx cluster and the H. subconcolor cluster, and the collections from Montana fall into the first of these clusters while those from Colorado fall in the latter cluster. Accordingly, the number of differences are between 2-23 [0-5] bp; seven pairs with 2-6 [0-1] bp differences and seven pairs with 20-23 [2-5] bp differences. Looking at all included collections, the overall figure hardly changes (1-23 bp), although the collections randomly selected from the FE dataset include representatives of all three clusters (Fig. 5). To date we have not observed any morphological or ecological differences between members of the different clusters. The geographical differentiation of the RM representatives of H. velutipes is possibly a sampling artifact.

This species displays the characteristic features of H. sect. Velutipes , i.e. the absence of a veil, presence of a velutinate stipe, and rather strongly dextrinoid spores (reaction can take a while), as well as the gently clavate cheilocystidia. It is known to be common and widely distributed in Europe at lower elevations primarily with deciduous trees but also with coniferous hosts. There are a number of arctic and alpine records, particularly from Svalbard with Dryas octopetala and Salix polaris ( Beker et al. 2016), and it has been previously reported from the North American alpine zone ( Beker et al. 2010). This species produces relatively large basidiomes for the genus in the alpine; but because of its pale coloration and lack of a veil, young specimens may have been incorrectly identified as H. alpinum or H. hiemale , which are typically smaller. Phylogenetically H. velutipes is not close to these two species but, as mentioned, is related to H. subconcolor , which is smaller with fewer lamellae, grayer coloration and is also reported from the Rocky Mountain alpine zone. Interestingly, almost all Rocky Mountain specimens of H. velutipes were found with Dryas , which might help with field recognition, in addition to its robust stature, and stout white stipe.