Hebeloma danicum (Photo: P. Derboven)

Taxonomy

Types: FRANCE: Ain, near Courmangoux (approx. 46.333°N, 5.367°E, alt. approx. 400 m a.s.l.) on soil under Carpinus betulus, 19 Oct. 1964, G. Bruchet (Holotype. herbarium acc. no. LY BR64-38, HJB1000108).

Heterotypic synonyms:

• Hebeloma lundqvistii Vesterh., Windahlia 20: 58 (1993)

Homotypic synonyms:

• Hebeloma birrus var. danicum (Gröger) Gminder 2010, Die Großpilze Baden-Württembergs Band 5 5: 650 (2010)

• arrow_drop_downarrow_drop_upEtymology
  From danicus– adj. form of Denmark. We presume this name was selected by Gröger in honour of the Danish mycologist Jacob Lange as he erected the species H. danicum as a replacement for the name H. spoliatum (Fr.) Gill. sensu Lange.

• arrow_drop_downarrow_drop_upOriginal diagnosis
  Pileus 40–45 mm latus, convexus, applanatus, leviter umbonatus, viscosus, saepe rugosus, brunneus, ad marginem pallidior. Lamellae confertae, brunneae, in margine siccae. Stipe 90–115 mm altus, 5 mm crassus, fistulosus, inferne fuscescens, longe radicatus. Cortina in primordiis adsens, fugacissima. Odor raphani sativi. Sapor raphani sativi et subamarus. Sporae amygdaliformes, verrucosae, 10–10.5 x 5–5,5 μm, s.m. luteo-brunneae, cum ectosporae remotae. Cheilocystidia brevia, 26–40 x 5–7 μm, subaequalia. Caulocystidia longiora. Epicutis normalis. Caespitosum in silva frondosa.

• arrow_drop_downarrow_drop_upEnglish translation
  Pileus 40–45 mm broad, convex, applanate, slightly umbonate, viscous, often rugose, brown, paler at margin. Lamellae crowded, brown, with dry edge. Stipe 90–115 mm high, 5 mm wide, fistulose, turning brown inside, with long root. Cortina present in primordia, very fugacious. Smell raphanoid. Taste raphanoid and slightly bitter. Spores amygdaloid, verrucose, 10–10.5 × 5–5.5 μm, yellow brown under microscope, with loosening perispore. Cheilocystidia short, 26–40 × 5–7 μm, subequal. Caulocystidia very long. Epicutis normal. Caespitose in deciduous forest.

Description

Description of Hebeloma danicum based on 23 collections

• arrow_drop_downarrow_drop_upMacroscopic description
  Pileus: (15) 17–45 (48) mm diameter; shape usually convex, occasionally umbonate or weakly umbonate; characters often remains of universal veil, occasionally rugulose; margin characters often involute, occasionally scalloped, smooth or sulcate; viscosity tacky when moist; colour variation often unicolour, occasionally two color; colour at centre often yellowish brown, occasionally ochraceous or cinnamon.

  Lamellae: attachment emarginate, occasionally adnate or adnexed; maximum depth 4–8 mm; number of complete lamellae 42–72; presence of tears absent; white fimbriate edge occasionally present, weak or very strong, rarely absent.

  Cortina presence: often no, occasionally yes.

  Stipe: (23) 35–96 (115) x 2–8 (11) {median} x (2) 3–13 (18) {basal} mm; stipe Q 6.4–23.0; base shape often clavate or cylindrical, occasionally tapering; floccosity often pruinose or fibrillose, occasionally floccose at apex or pruinose at apex; rooting usually yes, rarely no or weak; thick rhizoids at base absent;

  Context: Texture firm; stipe interior hollow or stuffed, occasionally superior wick; stipe flesh discolouring often yes, occasionally weak; slenderness measure 8.8–49.1; smell occasionally cocoa, odourless, raphanoid or soap; taste often mild, occasionally weakly bitter or raphanoid where recorded.

  Spore deposit colour: Not recorded.

  Exsiccata characters: occasionally dark, pileus blackening or stipe blackening, rarely hard.

• arrow_drop_downarrow_drop_upMicroscopic description
  Spores: shape amygdaloid; colour in microscope often brown or yellow brown, occasionally brown pale; guttules variable. papilla often no, occasionally weak; Spore Code: (O2) O3 (O4); (P1) P2 (P3); D3 (D4).

  Basidia: 17–30 (31) x 5–8 μm; ave. Q 2.5–4.1; spore arrangement 4 spored;

  Cheilocystidia: main shape cylindrical, occasionally clavate, rarely clavate-lageniform or clavate-ventricose or lageniform; special features observed often septa, occasionally short, apical thickening, clamped septa or many collapsed in exsiccata, rarely branching, geniculate, rostrate or tapering; cheilocystidia ratios: A/M = 0.97–1.24; A/B = 0.98–1.35; B/M = 0.87–1.20.

  Pleurocystidia: none seen.

  Ixocutis: epicutis thickness (measured from exsiccata) up to 320 μm; ixocutis hyphae width up to 7 μm; ixocutis hyphae encrustation yes; shape of trama elements beneath subcutis thickly sausage-shaped, occasionally ellipsoid, angular, cylindrical, polygonal or spherical up to 18 μm wide.

  Caulocystidia: Similar to cheilocystidia but larger, up to 80 μm.

• arrow_drop_downarrow_drop_upSpore measurements

• arrow_drop_downarrow_drop_upCheilocystidia measurements

• arrow_drop_downarrow_drop_upHabitat and distribution
  Hebeloma danicum's preferred habitat appears to be deciduous woodland or woodland with calcareous soil. Where only one possible associate was recorded, the most commonly recorded associate was Fagus (40.0%) but Quercus (20.0%), Castanopsis (20.0%), Carpinus (10.0%) and Picea (10.0%) were also recorded. In these cases the most commonly recorded families were Fagaceae (81.8%), Betulaceae (9.1%) and Pinaceae (9.1%). We have additional records where Corylus (12.5%), Pinus (6.2%), Abies (6.2%), Larix (6.2%) and Betula (6.2%) were recorded as possible associates, but in these cases a number of possible associates were mentioned. Overall the most commonly recorded families are Fagaceae (87.5%), Pinaceae (25.0%), Betulaceae (25.0%) and Rosaceae (6.2%) The growth habit of our collections was usually caespitose, occasionally scattered and rarely gregarious.

  According to our current data, the species is found on multiple continents with collections found in Europe (60.9%) and Temperate Asia (39.1%). On these continents, collections have been found only in the temperate broadleaf & mixed forests WWF biome 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. (Western European broadleaf forests (20.0%), Sarmatic mixed forests (15.0%) and Taiheiyo evergreen forests (15.0%) ecoregions). From collector information, it appears collections have been found in the 1.4 Forest – Temperate (81.2%) and 17.1 Quarry (12.5%) 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 North (Sweden, Denmark, Finland and England), the Centre (Poland and Germany), the Southwest (France) and the Southeast (Italy). Specimens have been collected from 41.8°N to 60.0°N.

  Within Temperate Asia all our records are from Eastern Asia (Japan).

• arrow_drop_downarrow_drop_upMolecular results
  Hebeloma danicum is well supported (96–100%) by bootstrap by all loci and in the results from concatenated data. Owing to the small number of recent collections we only obtained a single RPB2 and Tef1a sequence for this species, but ITS and the mitochondrial loci are sufficient to show that this species is supported phylogenetically. Our concept of H. danicum and synonymization between H. danicum and H. lundqvistii is supported by ITS data from the holotype (and in the case of H. lundqvistii also isotype) material from both species. We are not aware of any published ITS data from outside Europe that is likely to belong to this species.

• arrow_drop_downarrow_drop_upCommentary
  Hebeloma danicum, without annulus and with its rooting stipe, mainly cylindrical cheilocystidia and distinctly to strongly ornamented and strongly dextrinoid spores clearly belongs to H. sect. Scabrispora. It can be distinguished from other Hebeloma spp. with mainly cylindrical cheilocystidia based on the distinctly ornamented, strongly dextrinoid amygdaloid spores at least 9.5 μm long but less than 6 μm wide and with Q value less than 1.85 and while the perispore can often be distinctly loosening in few to many spores it is not strongly and constantly loosening. Further the number of complete lamellae (L) is at most 60, which separates this taxon from H. laterinum, which in any case is macroscopically quite different. There has in the past been much confusion between H. birrus, H. pumilum and H. danicum and the many other European names of similar Hebeloma species within H. sect. Scabrispora. Indeed, Vesterholt (2005) ‘lumped’ all these species together under the name H. birrus. We have a full discussion of this issue in the commentary and discussion following the description of H. birrus. As concerns Hebeloma danicum, it has larger spores than H. pumilum and its spores do not have the strongly and constantly loosening perispore (P3) of H. birrus. With regard to the veil, H. danicum does have a veil that is usually more persistent than that of H. birrus but usually less persistent than that of H. pumilum. The veil of H. danicum is almost always clearly visible on primordia and also on young basidiomes; as they age the veil disappears, but it often leaves fibrils on the stipe or on the pileus. This differs from H. birrus in that H. birrus, in our experience, never has any trace of the veil remaining on mature basidiomes. Hebeloma melleum is also similar but, ike H. pumilum, has shorter spores than H. danicum. In his treatment of this taxon, under the name Hebeloma lundqvistii, Vesterholt (2005) compares this taxon to H. syrjense and H. circinans, but he comments on the fact that both these species occur in conifer woodland, while H. lundqvistii occurs in calcareous deciduous woodland. As discussed above we have collections of this taxon from base-boor coniferous woodlands as well as from base-rich deciduous woodlands. But H. syrjense has smaller spores than H. danicum as well as cheilocystidia that are more clavate-lageniform; H. circinans has less ornamented and less dextrinoid spores. Gröger, when erecting this species, considered it to be H. spoliatum (Fr.) Gill. sensu Lange. This is almost certainly different from H. spoliatum sensu Fries. The type Gröger selected was the collection described by Bruchet (1970) as H. spoliatum (Fr.) Gill. sensu Lange. Given the various interpretations of H. spoliatum, we believe it safer to exclude this species from our synonyms for H. danicum.

Geographic distribution

Phenology

• arrow_drop_downarrow_drop_upAdditional cited collections

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