Hebeloma subconcolor (Photo: J. Vesterholt)

Taxonomy

Types: FRANCE: Cirque du Vallonnet (Vanoise;Savoie) (approx. 45.45°N, 7.03°E, alt. approx. 2500 m a.s.l.) on acidic, mossy, sandy soil in alpine meadow riverside under Salix herbacea, 9 Oct. 1969, G. Bruchet (Holotype. herbarium acc. no. LY BR69-12, HJB1000044).

Homotypic synonyms:

• Hebelomatis subconcolor (Bruchet) Locq. ;, Flore Mycologique Vol III - Text. Cortinariales A: 146 (1979) ["1977"]

• arrow_drop_downarrow_drop_upEtymology
  From sub– less than, and concolor– of the same colour, to emphasise that the pileus (almost unicoloured) and the stipe are almost but not quite the same colour.

• arrow_drop_downarrow_drop_upOriginal diagnosis
  Cortina nulla; pileo parvo, circiter 16 mm lato, haud viscoso, subtiliter toto pruinato, concolore, e brunneolo vel brunneo murino, carne pallide brunnea vel e brunneola murina; stipite toto dense pruinoso, pileo subconcolore, plerumque e breunneolo murino; lamellis crassis, parum stipatis, siccis, in juventute ad colorem murinum quoque vergentibus; odore nullo. Sporis 10–11 x 6–6,5 μm, ovatis, amygdaliformibus, non maximis, veruculosis vel verrucosis, ectospora s.m. opt. haud manifesta; pilis marginum summis paulatim dilatatis, usque ad 9–10 μm latis. Species alpina, inter Salices herbaceas crescit.

• arrow_drop_downarrow_drop_upEnglish translation
  Without cortina; pileus small, about 16 mm broad, not viscid, entirely delicately pruinose, concolourous, brownish then mouse grey, context pale brown to greyish brown, stipe entirely densely pruinose, same colour as pileus, very often brown then greyish brown; lamellae thick, attached to stipe, dry, also turning mouse-grey with age; smell none. Spores 10–11 × 6–6.5 μm, ovate, amygdaloid, not very ornamented, verruculose to verrucose, ectosporium under microscope not very distinct; marginal hairs with weakly inflated apex, up to 9–10 μm broad. Species from the alpine zone growing with Salix herbacea.

Description

Description of Hebeloma subconcolor based on 22 collections

• arrow_drop_downarrow_drop_upMacroscopic description
  Pileus: (8) 9–20 (21) mm diameter; shape often convex or umbonate, occasionally broadly umbonate; characters Not recorded; margin characters often involute or smooth; viscosity tacky when moist; colour variation often unicolour or two color; colour at centre occasionally clay-buff, sepia, yellowish brown or greyish brown.

  Lamellae: attachment emarginate, occasionally adnate; maximum depth 3–4 mm; number of complete lamellae 20–32; presence of tears often visible with naked eye, occasionally absent or visible with x10 lens; white fimbriate edge present.

  Cortina presence: no.

  Stipe: (10) 15–27 (32) x 3–4 (5) {median} x 3–7 (8) {basal} mm; stipe Q 2.9–10.7; base shape often clavate or cylindrical, occasionally bulbous; floccosity often fibrous or pruinose, occasionally pruinose at apex; rooting no; thick rhizoids at base absent;

  Context: Texture firm; stipe interior hollow, occasionally stuffed; stipe flesh discolouring often yes, occasionally weak; slenderness measure 4.0–22.9; smell often raphanoid, occasionally odourless or strongly raphanoid; taste bitter or raphanoid where recorded.

  Spore deposit colour: clay-buff.

  Exsiccata characters: Not recorded.

• arrow_drop_downarrow_drop_upMicroscopic description
  Spores: shape amygdaloid, occasionally ovoid, rarely limoniform; colour in microscope occasionally yellow, yellow brown, brown or very pale; guttules variable. papilla usually no, rarely yes; Spore Code: O1 O2; P0 (P1); D2 D3.

  Basidia: 25–39 (40) x 7–10 μm; ave. Q 3.2–3.9; spore arrangement 4 spored;

  Cheilocystidia: main shape gently clavate, often clavate or clavate-lageniform or clavate-ventricose, rarely cylindrical, lageniform, tapering or ventricose; special features observed occasionally apical thickening or septa, rarely bifurcate, geniculate, large or many collapsed in exsiccata; cheilocystidia ratios: A/M = 1.37–1.71; A/B = 1.36–1.86; B/M = 0.92–1.13.

  Pleurocystidia: none seen.

  Ixocutis: epicutis thickness (measured from exsiccata) up to 75 μm; ixocutis hyphae width up to 6 μm; ixocutis hyphae encrustation variable; shape of trama elements beneath subcutis often ellipsoid, isodiametric, polygonal or thinly sausage-shaped, occasionally thickly sausage-shaped up to 20 μm wide.

  Caulocystidia: Similar to cheilocystidia but larger, up to 120 μm.

• arrow_drop_downarrow_drop_upSpore measurements

• arrow_drop_downarrow_drop_upCheilocystidia measurements

• arrow_drop_downarrow_drop_upHabitat and distribution
  Hebeloma subconcolor's preferred habitat appears to be alpine meadow. Where only one possible associate was recorded, that associate has always been Salix (family Salicaceae). We have additional records where Polygonum was recorded as a possible associate, but for these collections a number of possible associates were mentioned. Overall the most commonly recorded families are Salicaceae (100.0%) and Polygonaceae (13.3%) The growth habit of our collections was usually scattered and occasionally solitary.

  According to our current data, the species is found on multiple continents with collections found in Northern America (61.9%) and Europe (38.1%). On these continents, collections has been found in the WWF biomes The World Wildlife Fund (WWF) have divided the world into 867 terrestrial ecoregions. The ecoregion here is estimated by mapping from the GPS coordinates of the collection using data made available by Dinerstein et al (2017). Use this webtool to explore the ecoregions visually or see a full list of current ecoregions on Wikipedia. tundra (47.6%) and temperate conifer forests (38.1%), specifically including the ecoregions: Kalaallit Nunaat Arctic steppe (42.9%) and Alps conifer and mixed forests (23.8%). From collector information, it appears collections have been found in the 5.11 Wetlands (inland) – Alpine wetlands (inc. temporary waters from snowmelt) (40.0%), 4.1 Grassland – Tundra (35.0%) and 5.10 Wetlands (inland) – Tundra wetlands (inc. pools and temporary waters from snowmelt) (15.0%) IUCN habitats We map from the collector's description of the habitat to the International Union for Conservation of Nature (IUCN)'s definition using a standardised set of rules. Please see this page for a full list of IUCN habitats..

  Within Northern America we have records from Subarctic America (Greenland) and Northwestern U.S.A. (Colorado and Washington).

  Within Europe we have records from the Centre (Switzerland), the North (Faroe Islands, Finland and Norway) and the Southwest (Italy and France). Specimens have been collected from 45.5°N to 62.8°N.

• arrow_drop_downarrow_drop_upMolecular results
  In its ITS, Hebeloma subconcolor is very close to the – within our sample – less common genotype of H. velutipes. Species identification by ITS barcodes is therefore impossible. Among the loci that separate H. subconcolor from H. velutipes, V9 is the easiest to obtain. We obtained sequences of ITS, V6 and V9 from holotype material, thus supporting our concept of H. subconcolor. In spite of the molecular similarity to H. velutipes and H. leucosarx, H. subconcolor forms monophyla in three out of five loci. This could be an effect of the small sample size. However, some of the cited collections come from geographically diverse localities.

• arrow_drop_downarrow_drop_upCommentary
  Given the shape of its cheilocystidia together with the spores distinctly dextrinoid to rather strongly dextrinoid, Hebeloma subconcolor clearly belongs to H. sect. Velutipes and belongs to the velutipes-complex, although it is macroscopically quite distinct. Within this section, it is easily separated on the number of complete lamellae (L at most 32). It certainly appears to be restricted to Salix and, as mentioned above, all our records specify Salix herbacea, and it also appears to be restricted to arctic/alpine habitats. While at present we have only nine recorded collections of H. subconcolor, they are widely distributed and we would suspect that it is widely distributed throughout the arctic and alpine regions of Europe and possibly further afield. It might be possible to confuse this taxon with one of the small arctic/alpine species of H. sect. Denudata such as H. minus or H. pallidolabiatum, but, as well as the different cheilocystidia, the spores are also rather different, being weakly ornamented and distinctly to rather strongly dextrinoid. It appears morphologically and molecularly close to H. velutipes which can also be found in arctic and alpine habitats, but the latter is significantly larger and has more lamellae, making a macroscopic separation straightforward. The etymology could be confusing. While we do have collections where the pileus is almost unicoloured and concolourous with the stipe, we do also have collections where the pileus is distinctly two-coloured and not concolourous with the stipe.

Geographic distribution

Phenology

• arrow_drop_downarrow_drop_upAdditional cited collections

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