Hebeloma pumilum (Photo: H. J. Beker)

Taxonomy

• arrow_drop_downarrow_drop_upNomenclatural notes
  Replacemant name for Hebeloma pumilum J.E. Lange (1938).

Types: Lange, Danmarks Agaricaceer. Held at Herbarium, Natural History Museum of Denmark, University of Copenhagen: 4 (1893-1910) Pl. 457, lectotype (icon) designated by Beker et al., Hebeloma (Fr.) P. Kumm.: (2016) page 463 (MBT202548) DENMARK: WJ, Vrogum,Vrogum Plantage NW of Oksby (approx. 55.65°N, 8.29°E, alt. approx. 15 m a.s.l.) on mossy soil in boreal, coniferous woodland under Picea sp., 3 Nov. 2002, J. Vesterholt (02-890) (Epitype. herbarium acc. no. C D-F-40666, BR 5020184114527 (isoepitype), HJB11593). Epitype designated by Beker et al., Hebeloma (Fr.) P. Kumm.: (2016) page 463 (MBT202549).

• arrow_drop_downarrow_drop_upType notes
  Lectotype (icon) later reproduced as plate 119b in Lange, Fl. Agaric. Danica 3 (1938).

Heterotypic synonyms:

• Hebeloma birrus var. herrmanniae (Gröger) Gminder, Die Großpilze Baden-Württembergs Band 5 5: 650 (2010)
• Hebeloma herrmanniae Gröger, Mykologisches Mitteilungsblatt 28 (1): 6 (1985)

Homotypic synonyms:

• Hebeloma birrus var. pumilum (J.E. Lange) Gminder, Die Großpilze Baden-Württembergs Band 5 5: 650 (2010)
• Hebeloma pumilum J.E. Lange, Dansk Botanisk Arkiv 9 (6): 6 (1938)

• arrow_drop_downarrow_drop_upEtymology
  From pumilus– dwarf-like, short.

• arrow_drop_downarrow_drop_upOriginal diagnosis
  Pileo 1–2,5 cm, convexo, pallide argillaceo, disco subfulvo-brunneo, margine albido, velo fugacissimo, fibrilloso. Lamellis latis, late emarginatis, guttulatis, margine minute fimbriato. Stipite 3–4 cm x 2–4 mm, cylindraceo, subradiato, albido, sursum leviter pruinato. Odor fere nullo. Sporis ovatis vel sublimoniformibus, 8,5–9 x 5,5 μm. Cystidiis brevibus, 25 x 4–5 μm, subclavatis. In fagetis ad terram denudatam. 1912.

• arrow_drop_downarrow_drop_upEnglish translation
  Pileus 1–2.5 cm, convex, pale brown with darker reddish brown disc and white margin, with fugacious fibrillose veil. Lamellae broad, broadly emarginate, weeping, with minutely fimbriate edge. Stipe 3–4 cm × 2–4 mm, cylindrical, slightly fibrillose, whitish, at apex slightly pruinose. Smell almost none. Spores ovate to sublimoniform, 8.5–9 × 5.5 μm. Cystidia short, 25 × 4–5 μm, subclavate. In Fagus forest on naked soil. 1912.

Description

Description of Hebeloma pumilum based on 36 collections

• arrow_drop_downarrow_drop_upMacroscopic description
  Pileus: (6) 10–35 (57) mm diameter; shape usually convex, rarely broadly umbonate or umbonate; characters often remains of universal veil, rarely hygrophanous or rugulose; margin characters often smooth, occasionally involute, rarely wavy or scalloped; viscosity tacky when moist; colour variation often two color, occasionally unicolour; colour at centre occasionally ochraceous, yellowish brown, dark brick or orange-brown, rarely umber, sepia or buff-yellow.

  Lamellae: attachment emarginate, rarely adnate; maximum depth 2–5 mm; number of complete lamellae 27–69; presence of tears absent; white fimbriate edge occasionally absent, weak or present.

  Cortina presence: often no, occasionally yes.

  Stipe: (18) 29–64 (120) x (1) 2–8 (19) {median} x (1) 2–11 (17) {basal} mm; stipe Q 2.8–27.3; base shape often cylindrical, occasionally clavate, rarely tapering or bulbous; floccosity occasionally pruinose, floccose, fibrillose or pruinose at apex, rarely floccose at apex, weakly floccose or velute; rooting often yes, occasionally weak, rarely no; thick rhizoids at base usually absent, rarely present;

  Context: Texture firm; stipe interior often hollow or stuffed, rarely superior wick; stipe flesh discolouring variable occasionally weak; slenderness measure 6.0–93.4; smell occasionally odourless, fruit or soap, rarely tea or aniseed; taste occasionally weakly bitter or mild, rarely hot or none where recorded.

  Spore deposit colour: often brownish olive, occasionally umber.

  Exsiccata characters: occasionally hard or dark, rarely shiny.

• arrow_drop_downarrow_drop_upMicroscopic description
  Spores: shape amygdaloid, occasionally limoniform; colour in microscope often yellow brown, occasionally brown or brown yellow, rarely yellow; guttules usually yes, rarely no. papilla often no, occasionally yes, rarely weak; Spore Code: (O2) O3; P1 P2; D3 D4.

  Basidia: (10) 19–32 x 5–8 μm; ave. Q 2.8–5.0; spore arrangement 4 spored;

  Cheilocystidia: main shape cylindrical, occasionally lageniform, rarely clavate or gently clavate; special features observed often short, occasionally septa or papillate, rarely branching, clamped septa, many collapsed in exsiccata, median thickening or rostrate; cheilocystidia ratios: A/M = 1.01–1.25; A/B = 0.85–1.23; B/M = 0.92–1.23.

  Pleurocystidia: often none seen, occasionally only close to lamella edge.

  Ixocutis: epicutis thickness (measured from exsiccata) up to 250 μm; ixocutis hyphae width up to 5 μm; ixocutis hyphae encrustation yes; shape of trama elements beneath subcutis thickly sausage-shaped, often ellipsoid, occasionally cylindrical, isodiametric or spherical up to 22 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 pumilum's preferred habitat appears to be coniferous, subalpine woodland. Where only one possible associate was recorded, the most commonly recorded associate was Pinus (59.1%) but Picea (18.2%), Fagus (18.2%) and Abies (4.5%) were also recorded. In these cases the most commonly recorded families were Pinaceae (83.3%) and Fagaceae (16.7%). We have additional records where Quercus (6.9%), Betula (3.5%), Larix (3.5%) and Castanea (3.5%) were recorded as possible associates, but in these cases a number of possible associates were mentioned. Overall the most commonly recorded families are Pinaceae (86.2%) and Fagaceae (27.6%) The growth habit of our collections was often scattered and occasionally caespitose or gregarious.

  According to our current collections, the species is predominantly found in Europe (97.2%) but also found in Temperate Asia (2.8%). 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. temperate broadleaf & mixed forests (42.4%), mediterranean forests, woodlands & scrub (24.2%), unknown biome (15.2%) and temperate conifer forests (12.1%), specifically including the ecoregions: Iberian conifer forests (24.2%), Unknown region (15.2%), Pyrenees conifer and mixed forests (15.2%) and Alps conifer and mixed forests (12.1%). From collector information, it appears collections have been found in the 1.1 Forest – Boreal (84.0%) and 1.4 Forest – Temperate (16.0%) 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 Europe we have records from the Southwest (Spain and France), the Centre (Germany, Poland and Austria), the North (Denmark, Norway and England) and the Southeast (Italy). Specimens have been collected from 41.2°N to 66.9°N.

  Within Temperate Asia all our records are from Caucasus (Adygea).

• arrow_drop_downarrow_drop_upMolecular results
  Hebeloma pumilum is monophyletic and well bootstrap-supported by ITS, V6, V9 and Tef1a and also in the result of all five loci concatenated, although there is not a single collection for which we obtained five loci. Although the RPB2 locus can be difficult to obtain, it is often the initial amplification that is not working, whereas in H. pumilum it was the sequencing step which was not successful. We only managed to obtain a single sequence for this locus. The ITS of the epitype of H. pumilum has been obtained. It not only supports our circumscription of the species, but also the synonymization of H. herrmanniae with H. pumilum. The latter is not only supported by ITS, but also by mitochondrial sequence data of the type of H. herrmanniae. We are not aware of any ITS data likely to belong to H. pumilum from outside Europe.

• arrow_drop_downarrow_drop_upCommentary
  With its tendency to root, its normally conspicuous veil remnants on the pileus and stipe and its mainly cylindrical cheilocystidia, Hebeloma pumilum clearly belongs to H. sect. Scabrispora. Within this section, the short spores (on average at most 9 μm), many of which are distinctly ornamented (O3) and strongly dextrinoid (D3 or D4), distinguish this taxon. In the field it is often possible to determine this species based on the habitat, the rich brown pileus and the veil remnants. In the past this species has been confused with Hebeloma birrus, see for instance Vesterholt (2005). This led to a belief that H. birrus had quite variable spore size. In fact this is not the case; H. birrus spores are always on average at least 9 μm long and less than 11 μm long. Hence microscopically these species can be separated quite easily. In the field the veil remnants are an important distinguishing character. Hebeloma melleum is closely related to H. pumilum, but it has longer spores and a more honey coloured pileus. Hebeloma danicum is also similar in appearance and can occur in coniferous woodlands. It can also exhibit veil remnants on the pileus and stipe, particularly in young basidiomes, however, like H. birrus, it too has longer spores (greater than 9.5 μm). Lange did not select any material as holotype for this taxon. However his illustration serves as an excellent lectotype. In order to ensure a precise application of the name of this taxon, we have designated an epitype; we have chosen a collection from Denmark.

Geographic distribution

Phenology

• arrow_drop_downarrow_drop_upAdditional cited collections

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