Hebeloma nitidum (Photo: D. Lewis)

Taxonomy

Types: UNITED STATES: Tennessee: Knoxville, Hardin Valley Rd. (approx. 35.9189°N, 84.2161°W, alt. approx. 260 m a.s.l.), 2 Jan. 1955, L.R. Hesler (LRH21622) (Holotype. herbarium acc. no. TENN-F-021622, HJB1000443).

Heterotypic synonyms:

• Hebeloma hydrocybeoides A.H. Sm., V.S. Evenson & Mitchel, The Veiled Species of Hebeloma in the Western United States: 168 (1983)
• Hebeloma politum Hesler, Kew Bulletin 31 (3): 478 (1977)

• arrow_drop_downarrow_drop_upEtymology

• arrow_drop_downarrow_drop_upOriginal diagnosis
  Pileus 2.5-7 cm latus, subfuscus demum sepiaceus, perglutinosus, siccitate valde politus glaber. Odor blandus, gustus subamarus. Lamellae emarginatae, albidae, denique brunneae confertae, dorsaliter latae, ventraliter angustatae. Stipes 4-7 cm longus, 6-15 mm crassus, supra pallidus, infra fuscus, apice farinaceus, infra fibrillosus. Velum tenue, textile, fugax. Sporae 8.5-10.5 x 5-5.5(-6) μm, sublimoniformes demum subfusiformes, rugulosae, leviter calyptratae. Pleurocystidia desunt; cheilocystidia 26-40 x 3-5 μm, filamentosa. Pilei trama radiale. Hypodermium cellulare. (Pl. 17; Figs. 3C-D.)

• arrow_drop_downarrow_drop_upEnglish translation
  Pileus 2.5-7 cm broad, pale brownish then almost dark reddish-brown, strongly glutinous, very shining when dry, glabrous. Smell mild, taste bitterish. Lamellae emarginate, whitish, then brown crowded, dorsally (towards the back) broad, ventrally (towards the underside) narrowed. Stipe 4-7 cm long, 6-15 mm thick, pale above, darkish below, fibrillose downwards. Veil thin, intertwined, vanishing. Spores 8.5-10.5 x 5-5.5 (-6) μm, sublimoniform then subfusiform, roughened, slightly calyptrate. Pleurocystidia none; cheilocystidia 26-40 x 3-5 μm, filamentous. Pilus trama radial. Hypoderm cellular. (Pl. 17; Figs. 3C-D.)

Description

Description of Hebeloma nitidum based on 14 collections

• arrow_drop_downarrow_drop_upMacroscopic description
  Pileus: (20) 28–46 (70) mm diameter; shape usually convex, occasionally umbonate; characters Not recorded; margin characters often involute or smooth, occasionally reflexed or wavy; viscosity tacky when moist; colour variation unicolour; colour at centre often greyish brown, occasionally brownish olive or brick.

  Lamellae: attachment usually emarginate, occasionally adnate or adnexed; maximum depth up to 5 mm; number of complete lamellae 52–64; presence of tears absent; white fimbriate edge often present, occasionally weak.

  Cortina presence: usually no, rarely yes.

  Stipe: (25) 39–93 (130) x (2) 3–10 (15) {median} x (2) 3–10 (15) {basal} mm; stipe Q 4.7–16.0; base shape cylindrical, occasionally clavate or tapering; floccosity usually fibrillose, often pruinose at apex, occasionally fibrous; rooting yes; thick rhizoids at base absent;

  Context: Texture firm; stipe interior usually hollow, occasionally stuffed; stipe flesh discolouring often yes, occasionally no; slenderness measure 7.7–42.1; smell odourless; taste often bitter, occasionally weakly bitter where recorded.

  Spore deposit colour: clay-buff.

  Exsiccata characters: Not recorded.

• arrow_drop_downarrow_drop_upMicroscopic description
  Spores: shape usually amygdaloid, often limoniform; colour in microscope usually brown, often yellow brown; guttules variable. papilla usually yes, rarely weak; Spore Code: O3 O4; (P2) P3; D3 D4.

  Basidia: (21) 23–37 (44) x 5–8 μm; ave. Q 3.7–4.8; spore arrangement 4 spored;

  Cheilocystidia: main shape cylindrical or ventricose, rarely clavate-lageniform or clavate-ventricose, lageniform or pyriform; special features observed occasionally branching or septa, rarely many collapsed in exsiccata, irregular, geniculate, rostrate or sinuate; cheilocystidia ratios: A/M = 0.98–1.20; A/B = 0.74–1.03; B/M = 1.10–1.39.

  Pleurocystidia: none seen.

  Ixocutis: epicutis thickness (measured from exsiccata) up to 400 μm; ixocutis hyphae width up to 6 μm; ixocutis hyphae encrustation often yes, occasionally no; shape of trama elements beneath subcutis thickly sausage-shaped, often cylindrical, occasionally ellipsoid or isodiametric up to 17 μm wide.

  Caulocystidia: Similar to cheilocystidia but larger, up to 100 μm.

• arrow_drop_downarrow_drop_upSpore measurements

• arrow_drop_downarrow_drop_upCheilocystidia measurements

• arrow_drop_downarrow_drop_upHabitat and distribution
  Hebeloma nitidum's preferred habitat appears to be woodland, deciduous woodland streamside or meadow with soil or cadaveric soil. Where only one possible associate was recorded, the most commonly recorded associate was Quercus (66.7%) but Pinus (33.3%) were also recorded. In these cases the most commonly recorded families were Fagaceae (66.7%) and Pinaceae (33.3%). Overall the most commonly recorded families are Fagaceae (57.1%) and Pinaceae (28.6%) The growth habit of our collections was often gregarious and rarely caespitose, scattered or solitary.

  According to our current collections, the species is found only in Northern America. On the continent, 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. temperate conifer forests (64.3%) and temperate broadleaf & mixed forests (28.6%), specifically including the ecoregions: Piney Woods (64.3%) and Appalachian-Blue Ridge forests (21.4%). From collector information, it appears collections have been found in the 1.4 Forest – Temperate (85.7%) and 4.4 Grassland – Temperate (14.3%) 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 South-central U.S.A. (Texas), Southeastern U.S.A. (Tennessee and Louisiana) and Northeastern U.S.A. (Michigan).

• arrow_drop_downarrow_drop_upCommentary
  In the latin diagnosis, we find a difficulty. It would seem to mean that in cross-section the lamella is wedge-shaped, that is to say, thick at the attachment to the pileus context and thin on the edge, but this would be unusual in a description; maybe the sense might be broad at the attachment to the stipe and thin at the outermost end.

Geographic distribution

Phenology

• arrow_drop_downarrow_drop_upAdditional cited collections

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