Hebeloma sacchariolens (Photo: H. J. Beker)

Taxonomy

Types: Quélet, Bull. Soc. Amis Sci. Nat. Rouen 2éme 15: 158 (1880) ["1879"] pl. 1 fig. 2, lectotype (icon) designated by Beker et al., Hebeloma (Fr.) P. Kumm.: (2016) page 529 (MBT202546) ENGLAND: Surrey, La Baraka, Gorse Hill Road, Virginia Water (51.4094°N, 0.565°W, alt. approx. 70 m a.s.l.) on grassy soil in urban garden under Betula pendula, 18 Nov. 2002, H.J. Beker (Epitype. herbarium acc. no. BR 5020184120412, HJB8483). Epitype designated by Beker et al., Hebeloma (Fr.) P. Kumm.: (2016) page 529 (MBT202547).

Heterotypic synonyms:

• Hebeloma latifolium Gröger & Zschiesch., Z. Mykol. 47 (2): 198 (1981)
• Hebeloma odoratum Velen., Ceske Houby: 394 (1919) ["1920"]
• Hebeloma pallidoluctuosum Gröger & Zschiesch., Wissenschaftliche Zeitschrift der Friedrich-Schiller-Universität Jena/Thüringen. Mathematisch-naturwissenschaftliche Reihe 33 (6): 815 (1984)
• Hebeloma sacchariolens var. pallidoluctuosum (Gröger & Zschiesch.) Quadr., Mycotaxon 30: 309 (1987)

Homotypic synonyms:

• Hylophila sacchariolens (Quél.) Quél., Enchiridion Fungorum in Europa Media et Praesertim in Gallia Vigentium: 100 (1886)

• arrow_drop_downarrow_drop_upEtymology
  Saccharinus– sugary, and olens– smelling, so smelling of [burnt] sugar.

• arrow_drop_downarrow_drop_upOriginal diagnosis
  Stipe grêle, subfistuleux, striolé, soyeux, pruineux au sommet, blanc avec des fibrilles fauvatres à la base. Chapeau campanulé-convexe (0m,02–3), mince, glabre, visqueux, blanchâtre, avec le disque fauvatre. Lamelles sinuées-adnées, crênelées, blanchâtres, puis chamois, avec la marge blanche. Spore en amande (0mm,012), fauve. Il exhale une forte odeur de sucre brûlé (Pl. 1, fig. 2) [Fig. 82.4 (colour)]. - Automne. - En troupe dans les bois siliceux. Normandie (A.L. Breton), Montmerency (Boudier), Vosges.

• arrow_drop_downarrow_drop_upEnglish translation
  Stipe slender, slightly hollow, striate, silky, pruinose at apex, white with tawny fibrils at the base. Pileus campanulate-convex (2–3 cm), thin, glabrous, viscous, whitish, with a tawny centre. Lamellae sinuate-adnate, with denticulate edge, whitish then leather-coloured, with white edge. Spores amygdaloid (12 μm), reddish brown. It has a strong smell of burnt sugar. Autumn. In groups in sandy forests. Normandy (A.L. Breton), Montmerency (Boudier), Vosges.

Description

Description of Hebeloma sacchariolens based on 125 collections

• arrow_drop_downarrow_drop_upMacroscopic description
  Pileus: (13) 17–42 (71) mm diameter; shape often convex, occasionally umbonate, rarely broadly umbonate or weakly umbonate; characters occasionally spotting or hygrophanous, rarely tomentose or rimulose; margin characters usually smooth, rarely eroded, crenulate, flexuous or involute; viscosity tacky when moist; colour variation often two color, occasionally unicolour; colour at centre occasionally dark pinkish buff, rarely ochraceous, yellowish brown, cream, clay-buff, warm buff, cinnamon, pale yellow, pale cream or honey.

  Lamellae: attachment usually emarginate, rarely adnate, decurrent tooth or free; maximum depth 2–10 mm; number of complete lamellae 31–58; presence of tears absent; white fimbriate edge occasionally weak or absent, rarely present.

  Cortina presence: no.

  Stipe: (13) 22–73 (90) x (2) 3–8 (10) {median} x (2) 3–7 (10) {basal} mm; stipe Q 3.8–20.3; base shape usually cylindrical, occasionally tapering, rarely clavate; floccosity occasionally fibrillose, none or pruinose at apex, rarely pruinose, velute or floccose at apex; rooting no; thick rhizoids at base absent;

  Context: Texture firm; stipe interior often hollow, occasionally stuffed, rarely superior wick; stipe flesh discolouring variable rarely weak or very strongly; slenderness measure 5.4–29.1; smell usually sacchariolentia, often sweet, rarely cocoa, fruit or raphanoid; taste often mild, occasionally weakly bitter or weakly raphanoid where recorded.

  Spore deposit colour: often brownish olive, occasionally umber, rarely sepia.

  Exsiccata characters: occasionally pileus blackening or stipe blackening, rarely fragile, lamellae blackening, pale or shiny.

• arrow_drop_downarrow_drop_upMicroscopic description
  Spores: shape amygdaloid, usually limoniform, rarely fusoid; colour in microscope usually brown, rarely yellow brown; guttules variable rarely weak. papilla often yes, occasionally very strongly, rarely no; Spore Code: O3 O4; P2 P3; D3 D4.

  Basidia: (24) 26–44 (45) x (6) 7–9 μm; ave. Q 3.1–4.8; spore arrangement often 4 spored or variable;

  Cheilocystidia: main shape often gently clavate or cylindrical, occasionally balloon-shaped, clavate, ventricose or lageniform, rarely filiform, pyriform, tapering, utriform or clavate-lageniform or clavate-ventricose; special features observed often septa or short, occasionally clamped septa or irregular, rarely branching, geniculate, many collapsed in exsiccata, bifurcate, large, rostrate, sparse or uniform; cheilocystidia ratios: A/M = 0.94–1.61; A/B = 0.98–2.17; B/M = 0.50–1.29.

  Pleurocystidia: none seen.

  Ixocutis: epicutis thickness (measured from exsiccata) up to 90 μm; ixocutis hyphae width up to 9 μm; ixocutis hyphae encrustation yes; shape of trama elements beneath subcutis often ellipsoid, occasionally isodiametric, oblong, thickly sausage-shaped or thinly sausage-shaped up to 30 μm wide.

  Caulocystidia: Similar to cheilocystidia but larger, up to 120 μm.

• arrow_drop_downarrow_drop_upSpore measurements

• arrow_drop_downarrow_drop_upCheilocystidia measurements

• arrow_drop_downarrow_drop_upHabitat and distribution
  Hebeloma sacchariolens's preferred habitat appears to be deciduous woodland with grassy soil or calcareous soil. Where only one possible associate was recorded, the most commonly recorded associate was Quercus (44.3%) but Fagus (18.0%), Betula (14.8%), Tilia (4.9%), Salix (3.3%), Populus (3.3%), Carpinus (3.3%), Picea (1.6%), Eucalyptus (1.6%), Corylus (1.6%), Castanea (1.6%) and Pseudotsuga (1.6%) were also recorded. In these cases the most commonly recorded families were Fagaceae (66.2%), Betulaceae (17.6%) and Salicaceae (5.9%). We have additional records where Pinus (2.9%) and Alnus (2.9%) were recorded as possible associates, but in these cases a number of possible associates were mentioned. Overall the most commonly recorded families are Fagaceae (73.1%), Betulaceae (41.4%), Pinaceae (9.6%), Rosaceae (7.7%) and Salicaceae (5.8%) The growth habit of our collections was usually scattered and rarely gregarious, solitary or caespitose.

  According to our current data, the species is found on multiple continents with collections found in Europe (74.4%), Northern America (19.8%), Temperate Asia (4.1%) and Australasia (1.6%). 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 (62.2%), temperate conifer forests (14.3%) and mediterranean forests, woodlands & scrub (11.8%), specifically including the ecoregions: English Lowlands beech forests (14.3%) and Puget lowland forests (12.6%). From collector information, it appears collections have been found in the 1.4 Forest – Temperate (62.9%) and 14.5 Urban Areas (34.0%) 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 North (England, Norway, Sweden and Denmark), the Centre (Belgium, Poland, Germany, Czech Republic and Slovakia), the Southeast (Italy and North Macedonia) and the Southwest (France, Spain, Channel Islands and Italy). Specimens have been collected from 39.9°N to 60.0°N.

  Within Northern America we have records from Northwestern U.S.A. (Washington and Oregon), Southwestern U.S.A. (California) and Western Canada (British Columbia).

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

  Within Australasia all our records are from New Zealand (New Zealand).

• arrow_drop_downarrow_drop_upMolecular results
  Hebeloma sacchariolens forms well supported monophyletic clades in analyses of all loci tested. Any of the tested loci can be used for identification, although the V6 of the mitSSU is quite variable within this taxon. Sequences of V6 form three distinct clades, of which two are well supported. However, these clades could not be matched with any other characters, molecular or morphological. The closest relatives of H. sacchariolens appear to be H. nauseosum and H. odoratissimum. Apart from the New Zealand collection mentioned above, there are no ITS sequences published from outside Europe.

• arrow_drop_downarrow_drop_upCommentary
  The smell of Hebeloma sacchariolens is very distinctive and variously described as ‘burnt sugar’, sweetish reminiscent of orange blossom (Citrus) or meadowsweet (Filipendula ulmaria). The spore width for this species, on average less than 7 μm, means it can only be H. sacchariolens, H. fusisporum or H. ischnostylum. The latter two have fusoid spores (Q > 1.8) and a pileus that is always white to ivory (other than through ageing); H. sacchariolens has average spore Q less than 1.8 and is usually two-coloured with brownish tones in the centre of the pileus. Also, H. sacchariolens appears to form mycorrhiza with a variety of deciduous trees, while both H. fusisporum and H. ischnostylum are rarely recorded with trees other than Salix or Alnus. Various authors (Gröger & Zschieschang 1981; Vesterholt 2005) have discussed the separation of H. sacchariolens and H. pallidoluctuosum based on the length of the cheilocystidia. This taxon has very variable cheilocystidia that can sometimes be difficult to locate on the non-sterile lamella edge. But, we can find no grounds on which to separate this into two taxa. The holotype of H. odoratum Velen. has been stored at PRC in a bottle containing an ethanol/formaldehyde solution. To our surprise, the material was in reasonable condition and, despite being unable to amplify DNA, we were able to study the material morphologically. We have no doubt that H. odoratum is a synonym of H. sacchariolens. Hebeloma sacchariolens is often recorded on account of its distinctive smell. However, we would guess that it is often confused with other members of this section that are not as well represented in the general literature.

Geographic distribution

Phenology

• arrow_drop_downarrow_drop_upAdditional cited collections

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