Hebeloma album (Photo: H. J. Beker)

Taxonomy

Types: UNITED STATES: New York: Essex County, Westport (approx. 44.18°N, 73.43°W, alt. approx. 50 m a.s.l.) on fallen soil and litter in woodland, 5 Oct. 1900, C.H. Peck (Holotype. herbarium acc. no. NYS-F-000175, HJB1000084; Isotype. herbarium acc. no. WTU-F-039674, HJB1000310).

Heterotypic synonyms:

• Hebeloma fragilipes Romagn., Bull. Trimestriel Soc. Mycol. France 81 (3): 341 (1929) ["1965"]
• Hebeloma domardianum (Maire) Beker, U. Eberh. & Vesterh., Fungi N. Eur. 3. 3: 102 (2005)
• Hebeloma barrowsii A.H. Sm., V.S. Evenson & Mitchel, The Veiled Species of Hebeloma in the Western United States: 87 (1983)
• Hebeloma kanouseae A.H. Sm., V.S. Evenson & Mitchel [as "kanousiae"], The Veiled Species of Hebeloma in the Western United States: 85 (1983)
• Hebeloma rivulosum Hesler, Kew Bulletin 31 (3): 479 (1977)
• Hebelomina domardiana Maire, Bulletin de la Société d’Histoire Naturelle de l’Afrique du Nord 26: 13 (1935)

Homotypic synonyms:

• Hebelomatis album (Peck) Locq., Flore Mycologique Vol III - Text. Cortinariales A: 146 (1979) ["1977"]

• arrow_drop_downarrow_drop_upEtymology
  From albus (Latin), meaning ‘white’.

• arrow_drop_downarrow_drop_upDiagnosis
  Pileus fleshy, firm, convex, becoming nearly plane or concave by the margin curving upward, glabrous, subviscid, white or yellowish white, flesh white; lamellae thin, narrow, close, emarginate, adnexed, whitish when young, becoming brownish ferruginous; stem equal. firm, rather long, solid or stuffed, slightly mealy at the top, white; spores subelliptic, pointed at one or both ends, .0005-.0006 of an inch long, .00025-.0003 broad [12.7-15.2 x 6.4-7.6 µm]. Pileus 1-2 inches broad [25.4-50.8 mm]; stem 1.5-3 inches long [38.1-76.2 mm], 2-3 lines thick [5.1-7.6 mm]. Among fallen leaves in woods. Westport. October. This is related to such species as H. elatius and H. longicaudum, from both of which it is distinguished by its white color. The lamellae are not serrate on the edge.

Description

Description of Hebeloma album based on 70 collections

• arrow_drop_downarrow_drop_upMacroscopic description
  Pileus: (13) 16–46 (70) mm diameter; shape occasionally convex, umbonate or broadly umbonate, rarely strongly umbonate; characters rarely remains of universal veil, spotting or rugulose; margin characters often smooth, occasionally involute, rarely scalloped or crenulate; viscosity tacky when moist; colour variation often unicolour, occasionally two color; colour at centre often cream, occasionally pale cream, rarely pale yellow, pinkish buff, warm buff or yellowish brown.

  Lamellae: attachment usually emarginate, rarely adnate; maximum depth 2–8 mm; number of complete lamellae 46–70; presence of tears often absent, occasionally visible with x10 lens or visible with naked eye; white fimbriate edge often present, occasionally weak.

  Cortina presence: no.

  Stipe: (15) 21–58 (75) x 3–7 (11) {median} x 3–12 (15) {basal} mm; stipe Q 2.5–22.7; base shape often clavate or cylindrical, rarely bulbous or tapering; floccosity often pruinose at apex, occasionally velute or pruinose, rarely floccose, floccose at apex, weakly floccose or fibrillose; rooting no; thick rhizoids at base absent;

  Context: Texture firm; stipe interior often stuffed or hollow; stipe flesh discolouring usually no, rarely yes or weak; slenderness measure 2.3–46.4; smell often raphanoid, rarely odourless, strongly raphanoid, weakly raphanoid, cocoa or earthy; taste occasionally bitter, strongly bitter, weakly bitter, mild, none or raphanoid where recorded.

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

  Exsiccata characters: occasionally fragile or stipe blackening.

• arrow_drop_downarrow_drop_upMicroscopic description
  Spores: shape amygdaloid, often limoniform, rarely fusoid; colour in microscope occasionally brown or yellow brown, rarely brown pale, very pale, yellow or brown yellow; guttules variable rarely weak. papilla often yes, rarely very strongly, weak or no; Spore Code: (O2) O3; P1 (P2); D2 D3.

  Basidia: (19) 21–36 (37) x (5) 6–9 (10) μm; ave. Q 2.9–4.1; spore arrangement 4 spored;

  Cheilocystidia: main shape clavate-lageniform or clavate-ventricose, occasionally clavate-stipitate, rarely ventricose, capitate-stipitate, clavate, gently clavate or cylindrical; special features observed occasionally septa, median thickening or apical thickening, rarely clamped septa, many collapsed in exsiccata, geniculate, yellow contents, sinuate or spathulate; cheilocystidia ratios: A/M = 1.15–2.50; A/B = 0.82–1.68; B/M = 1.35–1.91.

  Pleurocystidia: usually none seen, rarely seen or only close to lamella edge.

  Ixocutis: epicutis thickness (measured from exsiccata) up to 180 μm; ixocutis hyphae width up to 6 μm; ixocutis hyphae encrustation usually yes, rarely no; shape of trama elements beneath subcutis often isodiametric, occasionally ellipsoid or ovate, rarely cylindrical, thickly sausage-shaped or thinly sausage-shaped up to 20 μm wide.

  Caulocystidia: Similar to cheilocystidia but larger, up to 170 μm.

• arrow_drop_downarrow_drop_upSpore measurements

• arrow_drop_downarrow_drop_upCheilocystidia measurements

• arrow_drop_downarrow_drop_upHabitat and distribution
  Hebeloma album's preferred habitat appears to be mixed woodland. Where only one possible associate was recorded, the most commonly recorded associate was Populus (57.7%) but Betula (11.5%), Pinus (11.5%), Salix (7.7%), Quercus (3.9%), Fagus (3.9%) and Alnus (3.9%) were also recorded. In these cases the most commonly recorded families were Salicaceae (64.3%), Betulaceae (17.9%), Pinaceae (10.7%) and Fagaceae (7.1%). We have additional records where Carpinus (15.0%), Picea (11.7%), Tsuga (11.7%), Ostrya (10.0%), Larix (5.0%), Corylus (3.3%), Abies (3.3%), Tilia (1.7%) and Castanea (1.7%) were recorded as possible associates, but in these cases a number of possible associates were mentioned. Overall the most commonly recorded families are Salicaceae (55.0%), Betulaceae (41.7%), Pinaceae (40.0%) and Fagaceae (25.0%) The growth habit of our collections was often scattered, occasionally solitary and rarely gregarious or caespitose.

  According to our current data, the species is found on multiple continents with collections found in Northern America (59.4%) and Europe (40.6%). 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 (47.1%), boreal forests/taiga (17.6%) and temperate conifer forests (10.3%), specifically including the ecoregions: European Atlantic mixed forests (16.2%), Appalachian-Blue Ridge forests (14.7%) and Watson Highlands taiga (10.3%). From collector information, it appears collections have been found in the 1.4 Forest – Temperate (51.9%), 1.1 Forest – Boreal (22.2%) and 13.3 Coastal Sand Dunes (13.0%) 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 Northern America we have records from Northwestern U.S.A. (Oregon, Colorado, Washington and Wyoming), Subarctic America (Yukon, Alaska and Northwest Territories), Southeastern U.S.A. (North Carolina and Tennessee), Northeastern U.S.A. (New York and Pennsylvania), Eastern Canada (Newfoundland and Labrador and Quebec), Western Canada (British Columbia and Alberta), Southwestern U.S.A. (Utah) and South-central U.S.A. (New Mexico).

  Within Europe we have records from the Centre (Belgium, Germany, Poland and Netherlands), the Southwest (France and Spain), Eastern Europe (Lithuania, Estonia and Latvia) and the North (Denmark and Norway). Specimens have been collected from 40.8°N to 59.2°N.

• arrow_drop_downarrow_drop_upCommentary
  This species belongs in Hebeloma sect. Denudata subsect. Clepsydroida, owing to the mainly clavate-ventricose cheilocystidia, on average greater than 40 µm long, exhibiting some thickening of the median wall and the distinctly ornamented spores. Within this subsection, the pileus color, described as white to yellowish white would indicate that this taxon is similar to H. fragilipes and H. pseudofragilipes (Beker et al. 2016; Eberhardt et al. 2016). The spore size and pileus color rule out H. ingratum. Unfortunately, it was not possible to generate any molecular information from the type collection. However, based on morphological studies of type material and both morphological and molecular studies of relevant types and material that we believe represents these different species, we have concluded that H. album and H. fragilipes are conspecific. Other North American species representing the same taxon are H. barrowsii and H. kanouseae. Although it does appear that North American collections do generally have somewhat rougher and larger spores, we have found a sufficient number of collections with intermediate measurements to be convinced that this is a continuum. Hence, the synonymy is made here. Beker et al. (2016) demonstrated that the ITS does not distinguish between H. album and H. pseudofragilipes. Thus, it was fortunate that V6 data could be obtained from H. barrowsii and H. kanouseae. The molecular results support the synonymization of the latter two species with H. album.

Geographic distribution

Phenology

• arrow_drop_downarrow_drop_upAdditional cited collections

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