Hebeloma erumpens (Photo: E. Campo)

Taxonomy

• arrow_drop_downarrow_drop_upNomenclatural notes
  Replacement name for Hebeloma erumpens Contu (1989), nom inval. (Art. 40.1)

Types: ITALY: Sardinia, Pixina Nuxedda, Maracalagonis,Cagliari (approx. 39.28°N, 9.23°E, alt. approx. 10 m a.s.l.) on acidic, bare soil in Mediterranean maquis under Cistus monspeliensis and Cistus salviifolius, 6 Jan. 1988, M. Contu, L. Contu, S. Scoles, det: M. Conttu (Holotype. herbarium acc. no. CAG 880106/17, HJB1000079).

Heterotypic synonyms:

• Hebeloma theobrominum var. pruinosum (M.M. Moser) Quadr., Mycol. Helv. 3 (2): 201 (1989) ["1988"]
• Hebeloma truncatum var. pruinosum M.M. Moser, Sydowia 38: 176 (1986) ["1985"]

Homotypic synonyms:

• Hebeloma erumpens Contu, Bulletin trimestriel de la Société Mycologique de France 105 (2): 109 (1989)

• arrow_drop_downarrow_drop_upEtymology
  From erumpens, the present participle of erumpere– to erupt (‘erupting’) to emphasise the fact that it often appears to be ‘erupting’ from the earth, covered in earth and rock particles.

• arrow_drop_downarrow_drop_upOriginal diagnosis
  Pileus 2-4 mm latus, sat carnosus, explanatus, haud umbonatus, in medio semper residuis humi velique albi obtecto. Cutis separabilis, sicca, glabra, omnino flavobrunnea vel testaceo-brunnea, saepe in medio subnigra, margine haud striatus. Lamellae sat confertae vel confertae, fines, adnatae vel emarginatae, ochraceae, haud lacrymantes, acies concolor, saepe in siccis plus minusve albo. Stipes 2-3.5 × 0.4-0.8 (1) cm, pro ratione pilei curto, solidus, cylindraceus vel subconicus, exannulatus. Indumentum clare sericeo-fibrillosum, album, saepe diffractum, brunnescens. Plenus dein fistulosus. Mycelium album. Caro firma, alba, brunneo sub cute pilei et ad basin stipitis. Odor levis, post sectionem raphanoideus; sapor amariusculus. Velum haud visibilis, residuis supra cutis pilei albis, araneosis. Sporarum pulvis ochracea. Sporae 9.5-11.5 × 5.7-7.6 μm, pallide flavae, verruculosae, apiculatae, amygdaliformes, mono- vel pluriguttulatae, haud amyloideae. Basidia 25-30.5 × 7.6-9.5 μm, tetraspora, clavata, saepe fibulata. Lamelllarum trama regularis. Pleurocystidia nulla vel rariora. Cheilocystidia 28.5-47.5 x 5.7-7.6 μm, frequentia, sinuoso-capitata, vel cylindraceo-capitata, capitulus globosus, marcatus. Pileipellis ex hyphis cylindraceus intermixtisque usque 13.5 μm largis constituta, suprapellis gelatinosa. Fibulae numerosae. Habitatio mediterraneensis, semper inter cistos (C. monspeliensis L et C. salviifolius L.) ad terram sabulosam acidamque, typical ex humo erumpente ut Russula delica vel Cortinarius erumpens. In Sardinia vere frequens. Taxonomia: propter absentiam veli in sectione Denudata (Fr.) Sacc. subgeneris Hebelomae locandus est. Hebeloma album Peck sensu Bruchet probabiliter idem videtur sed species Peckii cheilocystidia lageniformia pileumque album vel vel pallidum hebet.

• arrow_drop_downarrow_drop_upEnglish translation
  Pileus 2–4 mm broad, rather fleshy, expanding, not umbonate, at centre covered with soil particles and remnants of white veil. Cuticle separable, dry, glabrous, entirely yellow-brown to reddish brown, often blackish at centre, margin not striate. Lamellae moderately crowded to crowded, thin, adnate to emarginate, ochre, not weeping, with concolourous edge, often whitish in dry state. Stipe 2–3.5 × 0.4–0.8 (1) cm, relatively short in comparison with pileus, solid, cylindrical to subconical, without annulus. Surface distinctly silky-fibrillose, white often turning brownish. Solid then fistulose. Mycelium white. Context firm, white, brown under cuticle of pileus and in base of stipe. Smell weak, raphanoid after cutting; taste bitterish. Veil not visible, remnants on pileus white, arachnoid. Spore print ochre. Spores 9.5–11.5 × 5.7–7.6 μm, pale yellow, verruculose, apiculate, amygdaloid, mono- or pluri-guttulate, not amyloid. Basidia 25–30.5 × 7.6–9.5 μm, four-spored, clavate, often clamped. Hymenophoral trama regular, Pleurocystidia absent or very rare. Cheilocystidia 28.5–47.5 × 5.7–7.6 μm, frequent, sinuous-capitate or cylindrical-capitate, with marked, globose capitulum. Pileipellis a cutis of intermixed cylindrical, up to 13.5 μm wide hyphae; suprapellis gelatinized. Clamps abundant. In Mediterranean habitat with Cistus (C. monspeliensis and C. salviifolius) on acid, sandy soil, typically coming out of the soil like Russula delica or Cortinarius erumpens. Frequent in Sardinia. Taxonomy: on account of the lack of veil to be placed in section Denudata of subgenus Hebeloma. Hebeloma album Peck sensu Bruchet is probably identical, but the Peck species differs by having lageniform cheilocystidia and a white to pale pileus.

Description

Description of Hebeloma erumpens based on 17 collections

• arrow_drop_downarrow_drop_upMacroscopic description
  Pileus: (20) 30–44 (55) mm diameter; shape often umbonate, occasionally convex; characters occasionally pruinose or remains of universal veil; margin characters smooth, occasionally eroded, involute or ribbed; viscosity tacky when moist; colour variation often two color, occasionally unicolour; colour at centre occasionally brick, fawn, ochraceous, orange-brown or dark brick.

  Lamellae: attachment emarginate, occasionally adnate; maximum depth 3–7 mm; number of complete lamellae 56–80; presence of tears usually absent, occasionally visible with naked eye; white fimbriate edge usually weak, occasionally absent.

  Cortina presence: no.

  Stipe: (20) 26–36 (50) x (4) 6–8 (12) {median} x (4) 6–9 (12) {basal} mm; stipe Q 2.2–6.3; base shape cylindrical, occasionally clavate or tapering; floccosity occasionally pruinose, fibrillose, none or pruinose at apex; rooting no; thick rhizoids at base absent;

  Context: Texture firm; stipe interior often hollow or stuffed; stipe flesh discolouring usually no, occasionally yes; slenderness measure 2.9–4.4; smell often weakly raphanoid, occasionally raphanoid, rarely cocoa or strongly raphanoid; taste bitter where recorded.

  Spore deposit colour: umber.

  Exsiccata characters: Not recorded.

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

  Basidia: (24) 25–39 (40) x 6–9 μm; ave. Q 3.7–4.2; spore arrangement 4 spored;

  Cheilocystidia: main shape clavate-lageniform or clavate-ventricose, often cylindrical, occasionally ventricose, rarely clavate or clavate-stipitate; special features observed often septa, occasionally short, rarely branching, median thickening, rostrate or yellow contents; cheilocystidia ratios: A/M = 1.41–2.08; A/B = 0.95–1.39; B/M = 1.35–1.60.

  Pleurocystidia: none seen.

  Ixocutis: epicutis thickness (measured from exsiccata) up to 200 μm; ixocutis hyphae width up to 7 μm; ixocutis hyphae encrustation variable; shape of trama elements beneath subcutis often ovate, occasionally cylindrical, ellipsoid or thickly sausage-shaped up to 13 μm wide.

  Caulocystidia: Similar to cheilocystidia but larger, up to 95 μm.

• arrow_drop_downarrow_drop_upSpore measurements

• arrow_drop_downarrow_drop_upCheilocystidia measurements

• arrow_drop_downarrow_drop_upHabitat and distribution
  Hebeloma erumpens's preferred habitat appears to be Mediterranean maquis or Mediterranean, mixed woodland with acidic, decomposed soil and litter or basic soil. Where only one possible associate was recorded, that associate has always been Cistus (family Cistaceae). We have additional records where Quercus was recorded as a possible associate, but for these collections a number of possible associates were mentioned. Overall the most commonly recorded families are Cistaceae (100.0%) and Fagaceae (14.3%) The growth habit of our collections was often scattered and occasionally gregarious.

  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. mediterranean forests, woodlands & scrub (87.5%) and unknown biome (12.5%), specifically including the ecoregions: Tyrrhenian-Adriatic sclerophyllous and mixed forests (37.5%), Northeast Spain and Southern France Mediterranean forests (25.0%), Unknown region (12.5%), Italian sclerophyllous and semi-deciduous forests (12.5%) and Iberian sclerophyllous and semi-deciduous forests (12.5%). From collector information, it appears collections have been found in the 3.8 Shrubland – Mediterranean-type shrubby vegetation (60.0%) and 1.4 Forest – Temperate (30.0%) 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, France and Italy) and the Southeast (Italy). Specimens have been collected from 38.7°N to 43.4°N.

• arrow_drop_downarrow_drop_upMolecular results
  Hebeloma erumpens is monophyletic and supported by bootstrap in the five-locus analysis, but the reality is more complicated due to ITS polymorphism in this species and H. griseopruinatum. Hebeloma erumpens can be recognized based on all analysed loci (except nucLSU) from all other species without problems apart from the very similar H. griseopruinatum. This taxon differs only in the ITS from H. erumpens and then only if a single ITS type is present. Collections with a single ITS type can be assigned correctly to species, but or both taxa, collections have been encountered that can be assigned morphologically to one of H. erumpens or H. griseopruinatum, but which contain ITS sequences of both taxa in their genomes (Eberhardt et al. 2012). The type of H. truncatum var. pruinosum, included in the description of H. erumpens, is an example. As indicated, we have not been able to amplify the ITS or any other locus from the type of H. erumpens.

• arrow_drop_downarrow_drop_upCommentary
  Hebeloma erumpens appears to be widespread, albeit not common, in Mediterranean scrub vegetation that contains Cistus. It is likely that it is Cistus-specific. The combination of almost smooth to very weakly ornamented and weakly but distinctly o very strongly dextrinoid spores, the clavate-lageniform shape of the cheilocystidia and the pruinose pileus all indicate H. sect. Theobromina. Hebeloma erumpens can be macroscopically distinguished from other species of H. sect. Theobromina by means of its habitat with Cistus and the pale pruinose covering of the fawn to brick coloured pileus. It is also very often found buried with remnants of earth and rock stuck to the pileus. Microscopically, the combination of weakly ornamented, smallish but quite wide spores (smallish Q), together with the clavate-lageniform shaped cheilocystidia with a relatively small average apex of the cystidium distinguish this species from other species of H. sect. Theobromina. Hebeloma erumpens appears phylogenetically very close to H. griseopruinatum as discussed above. Morphologically the two taxa can be distinguished based on several characters. However, both species appear to be uniquely associated with Cistaceae, albeit H. erumpens occurs with Cistus and H. griseopruinatum occurs with Helianthemum.

Geographic distribution

Phenology

• arrow_drop_downarrow_drop_upAdditional cited collections

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