Full name: Hebeloma magnicystidiatum A. Kong & Beker, Mycokeys 90: 183 (2022)
Genus: Hebeloma
Section: Denudata
Subsection: Crustuliniformia

Types: MEXICO: Tlaxcala, Municipality of Totolac, Tepeticpac (approx. 19.3457°N, 98.2227°W, alt. approx. 2400 m a.s.l.) on soil in montane, subtropical woodland under Pinus sp. and Quercus sp., 29 Aug. 1990, A. Estrada-Torres (T3093) (Holotype. herbarium acc. no. TLXM 6157 (holotype), BR5020224873599V (isotype), HJB16795).

  • arrow_drop_downarrow_drop_upEtymology
    From magni- (Latin, composite) meaning large and cystidiatus to emphasize the large capitate-stipitate cheilocystidia.
  • arrow_drop_downarrow_drop_upDiagnosis
    The amygdaloid, non-dextrinoid, rather strongly ornamented spores with average Q value less than 1.6 and the capitate-tipitate cheilocystidia with average width at the apex greater than 9.5 μm distinguish this species from all other known Hebeloma species.


  • arrow_drop_downarrow_drop_upThresholds
Description of Hebeloma magnicystidiatum based on 1 collections
  • arrow_drop_downarrow_drop_upMacroscopic description
    Pileus: (19) 22 (26) mm diameter; shape convex; characters remains of universal veil; margin characters Not recorded; viscosity tacky when moist; colour variation two color; colour at centre often orange-brown or umber.

    Lamellae: attachment adnexed or emarginate; maximum depth up to 5 mm; number of complete lamellae up to 60; presence of tears Not recorded; white fimbriate edge present.

    Cortina presence: no.

    Stipe: (10) 15 (21) x (4) 5 (6) {median} x (4) 5 (6) {basal} mm; stipe Q 2.5–3.5; base shape cylindrical; floccosity fibrillose or pruinose at apex; rooting no; thick rhizoids at base absent;

    Context: Texture firm; stipe interior Not recorded; stipe flesh discolouring yes; slenderness measure up to 2.1; smell raphanoid; taste mild where recorded.

    Spore deposit colour: Not recorded.

    Exsiccata characters: Not recorded.

  • arrow_drop_downarrow_drop_upMicroscopic description
    Spores: shape amygdaloid or limoniform; colour in microscope yellow brown; guttules no. papilla yes; Spore Code: O3; P1; D1.

    Basidia: 27–34 x 7–9 μm; ave. Q up to 3.9; spore arrangement 4 spored;

    Cheilocystidia: main shape capitate-stipitate; special features observed often many collapsed in exsiccata; cheilocystidia ratios: A/M = up to 2.58; A/B = up to 2.67; B/M = up to 0.95.

    Pleurocystidia: none seen.

    Ixocutis: epicutis thickness (measured from exsiccata) up to 110 μm; ixocutis hyphae width up to 7 μm; ixocutis hyphae encrustation no; shape of trama elements beneath subcutis cylindrical or ellipsoid up to 17 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 magnicystidiatum's preferred habitat appears to be montane, subtropical woodland. No associated genera are recorded for the species. No growth habit has been recorded.

    According to our current collections, the species is found only in Northern America. From collector information, it appears collections have been found in the 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 all our records are from Mexico (Mexico).

  • arrow_drop_downarrow_drop_upCommentary
    With its amygdaloid, hardly dextrinoid basidiospores and capitatestipitate cheilocystidia, morphologically this taxon clearly belongs to Hebeloma sect. Denudata and there to H. subsect. Crustuliniformia. The amygdaloid spores with rather small average Q value separate this species from all other studied Hebeloma from our database with more than 10,000 collections. While this may suggest that this is a rare species, we have insufficient Hebeloma collections from Mexico to reach such a conclusion. The single collection was collected in the 1990s, thus the only loci we could amplify were ITS and mitSSU variable regions V6 and V9. The phylogenetic placement of H. magnicystidiatum within H. sect. Denudata is unresolved. As pointed out before (e.g. Eberhardt et al. 2016, 2022b; Beker et al. 2016), the more species rich subsections of H. sect. Denudata (H. subsects Clepsydroida and Crustuliniformia) are not supported molecularly. In terms of ITS, the most similar species was H. sordidulum (H. subsect. Clepsydroida) with similarity values ≤ 98.7%. Possibly H. magnicystidiatum will correspond to a UNITE SH at the 99% or 98.5% level once sequences of this species are included in the system. Morphologically, the capitate-stipitate cheilocystidia together with the amygdaloid spores with av. Q less than 1.6 are sufficient characters to separate this species from members of H. sect. Clepsydroida, such as H. cavipes, H. matritense, H. sordidulum and H. vaccinum.
Geographic distribution
  • arrow_drop_downarrow_drop_upAdditional cited collections

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