Hebeloma pseudoamarescens (Photo: E. Bizio)

Taxonomy

Basionym:
Alnicola pseudoamarescens Kühner & Romagn., Annales Scientifiques de Franche-Comté 2: 10 (1947)

Types: FRANCE: Doubs, Avoudrey (approx. 47.138°N, 6.435°E, alt. approx. 700 m a.s.l.) on burnt soil in coniferous woodland under Abies sp., 14 Oct. 1946, R. Kuhner (Lectotype. herbarium acc. no. G00052669, HJB1000252). Lectotype designated by Beker et al., Hebeloma (Fr.) P. Kumm.: (2016) page 541 (MBT203473).

• arrow_drop_downarrow_drop_upType notes
  The lectotype designated is one of the two collections mentioned in the protologue.

Heterotypic synonyms:

• Hebeloma funariophilum M.M. Moser, Zeitschrift fuer Pilzkunde 36 (1-2): 61 (1970)
• Hebelomatis funariophilum (M.M. Moser) Locq., Flore Mycologique Vol III - Text. Cortinariales A: 146 (1979) ["1977"]

Homotypic synonyms:

• Naucoria pseudoamarescens (Kühner & Romagn.) Kühner & Romagn., Flore Analytique de Champignons Superieurs (Agarics, Bolets, Chanterelles): 236 (1953)

• arrow_drop_downarrow_drop_upEtymology
  From Greek pseudo– resembling but not equal to, false, and Latin amarus– bitter, based on its similarity to Alnicola amarescens, also found in burnt places and with a very bitter taste.

• arrow_drop_downarrow_drop_upOriginal diagnosis
  In humo ambusto. Pileo 8–28 mm lato, convexo et +/- mammoso, hygrophano, e luteo pullo vel ex ochraceo rufo-fulvo, glabro. Lamellis pullis, adnatis. Stipite 2,2–4,2 cm x 1,5–3,5 mm., aequali, e vestimento aerifero et +/- argentato-sericeo, ex fibrillis adpressis constant, diu albo vel pallido, postremo ad basim +/- fuscescenti. Sapore amaro. Spores amygdaliformibus, 9–11,5 x 4,5–6,2 μm, subtilissime punctatis. Pilis marginalibus capite clavulave ovate, +/- manifesta, sursum dilatatis, nec cuspidatis, ut in A. amarescentii, ep. cute pilei spissa, manifeste gelata, ex filiformibus hyphis constante.

• arrow_drop_downarrow_drop_upEnglish translation
  On burnt soil. Pileus 8–28 mm broad, convex and more or less umbonate, hygrophanous, dark yellow or ochre then reddish brown, glabrous. Lamellae dark, adnate. Stipe 2.2–4.2 × 1.5–3.5 mm, equal, with an aeriferous, more or less silvery-shiny covering, long white or pallid, then turning brown from base upwards. Taste bitter. Spores amygdaloid, 9–11.5 × 4.5–6.2 μm, subtly punctate. Marginal hairs with more or less distinct capitate-ovate head, not cuspidate, as in A. amarescens. Epicutis thick, distinctly gelatinized, made up of filiform hyphae.

Description

Description of Hebeloma pseudoamarescens based on 15 collections

• arrow_drop_downarrow_drop_upMacroscopic description
  Pileus: (5) 11–21 (30) mm diameter; shape often convex, occasionally umbonate, broadly umbonate, weakly umbonate or strongly umbonate; characters often hygrophanous, occasionally remains of universal veil; margin characters often smooth, occasionally crenulate, involute or sulcate; viscosity tacky when moist; colour variation unicolour; colour at centre yellowish brown.

  Lamellae: attachment often adnate or emarginate, occasionally decurrent tooth; maximum depth 1–4 mm; number of complete lamellae 26–40; presence of tears absent; white fimbriate edge often present, occasionally weak.

  Cortina presence: no.

  Stipe: (20) 25–64 (120) x (1) 2–3 (5) {median} x (1) 2–4 (5) {basal} mm; stipe Q 8.3–26.7; base shape often clavate or cylindrical; floccosity often pruinose at apex, occasionally fibrillose or none; rooting no; thick rhizoids at base absent;

  Context: Texture firm; stipe interior often hollow, occasionally stuffed; stipe flesh discolouring variable often weak; slenderness measure 17.5–67.1; smell often odourless or weakly raphanoid; taste often bitter or strongly bitter where recorded.

  Spore deposit colour: Not recorded.

  Exsiccata characters: usually rich brown color, often dark, occasionally fragile or hard.

• arrow_drop_downarrow_drop_upMicroscopic description
  Spores: shape amygdaloid, often fusoid, rarely ellipsoid; colour in microscope occasionally grey yellow, yellow, brown, brown pale, very pale, yellow pale or yellow brown; guttules often no, occasionally yes. papilla no; Spore Code: (O1) O2 (O3); (P0) P1 P2; D3.

  Basidia: 17–30 (32) x 5–7 (8) μm; ave. Q 2.9–4.1; spore arrangement 4 spored;

  Cheilocystidia: main shape clavate-lageniform or clavate-ventricose, often cylindrical, occasionally lageniform, ventricose, clavate-stipitate or gently clavate, rarely balloon-shaped, capitate, capitate-stipitate, clavate, filiform, lanceolate, lentiform, napiform, pedicilate, pyriform, spathulate, spathulate-stipitate, subcapitate, tapering, turbinate or utriform; special features observed often septa, short or geniculate, occasionally many collapsed in exsiccata, median thickening, irregular, clamped septa or rostrate, rarely branching or grotesque; cheilocystidia ratios: A/M = 1.41–1.64; A/B = 0.88–1.26; B/M = 1.29–1.67.

  Pleurocystidia: none seen.

  Ixocutis: epicutis thickness (measured from exsiccata) up to 375 μm; ixocutis hyphae width up to 6 μm; ixocutis hyphae encrustation often yes, occasionally no; shape of trama elements beneath subcutis often angular or thickly sausage-shaped, occasionally isodiametric up to 15 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 pseudoamarescens's preferred habitat appears to be woodland with burnt soil. Where only one possible associate was recorded, that associate has always been Abies (family Pinaceae). We have additional records where Populus, Salix, Betula, Pinus, Quercus, Castanea and Corylus were recorded as possible associates, but in these cases a number of possible associates were mentioned. Overall the most commonly recorded families are Salicaceae (50.0%), Betulaceae (50.0%), Pinaceae (33.3%) and Fagaceae (33.3%) The growth habit of our collections was often gregarious and occasionally scattered.

  According to our current collections, the species is found only in Europe. 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 broadleaf & mixed forests (46.2%) and temperate conifer forests (30.8%), specifically including the ecoregions: European Atlantic mixed forests (23.1%), Alps conifer and mixed forests (23.1%) and Western European broadleaf forests (15.4%). From collector information, it appears collections have been found only in the 1.4 Forest – Temperate 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 Europe we have records from the Southwest (France and Italy), the North (Denmark, Scotland and Norway), the Centre (Austria and Germany), Eastern Europe (Estonia) and the Southeast (Italy). Specimens have been collected from 42.1°N to 60.3°N.

• arrow_drop_downarrow_drop_upMolecular results
  All loci sequenced agree in that Hebeloma pseudoamarescens is rather isolated within the genus. The majority of loci (apart from V6) agree that it forms the sistergroup to all other Hebeloma sections, although this relationship is only supported by bootstrap in the Tef1a result and when concatenating all loci. The intraspecific variation of all loci sequenced for H. pseudoamarescens is negligible, thus supporting the section as monospecific. There are no ITS sequences published from outside Europe that are likely to belong to a member of this section.

• arrow_drop_downarrow_drop_upCommentary
  Hebeloma pseudoamarescens appears to be phylogenetically quite isolated within Europe. In fact, there has in the past been much debate over whether or not this taxon should be classified within the genus Hebeloma or in Alnicola or, indeed, somewhere in-between. We believe there is sufficient phylogenetic evidence that this taxon should be within Hebeloma. With its small amygdaloid or fusoid spores (on average less than 10 μm long) and the small number of complete lamellae (L at most 40), this species is easily distinguished from other Hebeloma spp. that regularly occur on burnt ground. However, its appearance is unusual, at first sight looking much more like an Alnicola (Naucoria). But Hebeloma pseudoamarescens does have the typical ixocutis (and viscid pileus) of a Hebeloma and it also has clamp connections. In our experience, it has no odour, but Romagnesi, in Kühner (1947), did suggest a weak raphanoid smell. Unfortunately, we were unable to get permission to try and sequence the lectotype collection, but we have no doubt that it is this taxon and we were able to sequence most of our other collections, including the holotype of Hebeloma funariophilum, which is undoubtedly the same taxon and we have synonymized it above.

Geographic distribution

Phenology

• arrow_drop_downarrow_drop_upAdditional cited collections

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