Hebeloma spetsbergense (Photo: J. Sandmo)

Taxonomy

Types: SVALBARD: Bjorndalen (78.2207°N, 15.334°E, alt. approx. 50 m a.s.l.) on acidic soil in arctic tundra pastureland under Salix polaris, 13 Aug. 2007, J. Sandmo (Holotype. herbarium acc. no. BR5020184126599, HJB11982).

• arrow_drop_downarrow_drop_upEtymology
  From Spetsbergia– Spitsbergen (Svalbard) which is the only location from which this fungus is known.

• arrow_drop_downarrow_drop_upDiagnosis
  Hebeloma spetsbergense has a persisting cortina and lageniform or ventricose cheilocystidia and is, therefore, a member of H. section Hebeloma. Within this section, the rather strongly dextrinoid amygdaloid spores, rarely limoniform, less than 14 μm long but more than 7.5 μm wide and basidiomes with less than 40 full length lamellae, distinguish this taxon from the other alpine/arctic species of this section.

Description

Description of Hebeloma spetsbergense based on 87 collections

• arrow_drop_downarrow_drop_upMacroscopic description
  Pileus: (8) 10–24 (35) mm diameter; shape often convex, occasionally broadly umbonate or applanate, rarely umbonate, umbilicate or papillate; characters rarely remains of universal veil or hygrophanous; margin characters smooth, occasionally wavy, rarely eroded; viscosity tacky when moist; colour variation often two color, occasionally unicolour; colour at centre occasionally sepia, dark brick or umber, rarely brownish olive, fuscous, yellowish brown, ochraceous or greyish brown.

  Lamellae: attachment usually emarginate, rarely adnate; maximum depth 2–5 mm; number of complete lamellae 18–36; presence of tears usually absent, rarely visible with x10 lens; white fimbriate edge occasionally weak or present, rarely absent.

  Cortina presence: yes.

  Stipe: (11) 13–29 (37) x 1–4 (8) {median} x 1–4 (7) {basal} mm; stipe Q 1.9–18.0; base shape usually cylindrical, rarely tapering or clavate; floccosity usually fibrillose, often pruinose at apex, rarely velute, pruinose or floccose at apex; rooting no; thick rhizoids at base absent;

  Context: Texture firm; stipe interior often hollow, occasionally stuffed; stipe flesh discolouring often no, occasionally yes, rarely weak or very strongly; slenderness measure 3.1–37.6; smell occasionally raphanoid or odourless, rarely cocoa, weakly raphanoid, strongly raphanoid, fruit or soap; taste weakly raphanoid where recorded.

  Spore deposit colour: often umber, occasionally sepia.

  Exsiccata characters: lamellae blackening or pileus blackening.

• arrow_drop_downarrow_drop_upMicroscopic description
  Spores: shape amygdaloid, occasionally ellipsoid, rarely ovoid or limoniform; colour in microscope often brown, occasionally yellow brown, yellow or brown pale; guttules variable rarely weak. papilla often no, occasionally weak; Spore Code: O1 O2; P0; D2 D3.

  Basidia: (23) 26–40 (44) x 7–10 (11) μm; ave. Q 3.1–4.0; spore arrangement 4 spored;

  Cheilocystidia: main shape ventricose, usually lageniform, occasionally clavate-lageniform or clavate-ventricose, rarely cylindrical, pyriform or gently clavate; special features observed occasionally septa, basal thickening, median thickening or clamped septa, rarely apical thickening, yellow contents, bifurcate, many collapsed in exsiccata, irregular, plaques, rostrate, slender or sparse; cheilocystidia ratios: A/M = 0.92–1.54; A/B = 0.43–1.10; B/M = 1.33–2.61.

  Pleurocystidia: usually none seen, rarely seen or only close to lamella edge.

  Ixocutis: epicutis thickness (measured from exsiccata) up to 60 μm; ixocutis hyphae width up to 7 μm; ixocutis hyphae encrustation variable; shape of trama elements beneath subcutis thickly sausage-shaped, often isodiametric, occasionally cylindrical up to 18 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 spetsbergense's preferred habitat appears to be arctic tundra with soil or mossy soil. Where only one possible associate was recorded, the most commonly recorded associate was Salix (98.5%) but Betula (1.5%) were also recorded. In these cases the most commonly recorded family was Salicaceae (97.0%). We have additional records where Dryas (5.3%), Larix (1.3%) and Picea (1.3%) were recorded as possible associates, but in these cases a number of possible associates were mentioned. Overall the most commonly recorded families are Salicaceae (96.0%), Polygonaceae (5.3%) and Rosaceae (5.3%) The growth habit of our collections was often scattered, occasionally solitary and rarely gregarious or caespitose.

  According to our current data, the species is found on multiple continents with collections found in Northern America (54.0%), Temperate Asia (26.4%) and Europe (19.5%). 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 (61.2%) and unknown biome (35.3%), specifically including the ecoregions: Unknown region (35.3%), Canadian High Arctic tundra (17.6%), Kalaallit Nunaat Arctic steppe (14.1%) and Russian Arctic desert (10.6%). From collector information, it appears collections have been found only in the 4.1 Grassland – Tundra IUCN habitat 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 (Nunavut, Greenland and Alaska) and Northwestern U.S.A. (Colorado).

  Within Temperate Asia all our records are from Russian Far East (Chukotka and Sakha).

  Within Europe all our records are from the North (Svalbard and Norway). Specimens have been collected from 61.3°N to 79.0°N.

• arrow_drop_downarrow_drop_upMolecular results
  Molecularly, H. spetsbergense is very similar to H. nigellum and other species from this clade and the only single locus for which H. spetsbergense is monophyletic and bootstrap-supported (97%) is Tef1a. Based on ITS it cannot be distinguished from all other species included in the H. clavulipes/H. nigellum clade.

• arrow_drop_downarrow_drop_upCommentary
  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. It is morphologically similar to H. nigellum and H. fuscatum. Until we have more collections of this species, it is difficult to be certain about its species delimitation.

Geographic distribution

Phenology

• arrow_drop_downarrow_drop_upAdditional cited collections

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