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Taxonomy

Full name: Hebeloma sagarae T. Kasuya, Mikami, Beker & U. Eberh., Phytotaxa 456 (2): 134 (2020)
Genus: Hebeloma
Section: Myxocybe

Types: JAPAN: Gifu, Hida-shi, Kamioka-cho, Utsubo (approx. 36.3961°N, 137.4008°E, alt. approx. 960 m a.s.l.) on nutrient-enriched (mole latrine) soil in woodland under Quercus serrata, 9 Oct. 2013, T. Kasuya, M. Mikami (TK-Kasuya B1352) (Holotype. herbarium acc. no. TNS F-79671 (holotype), TNS F-79672 (isotype), TNS F-79673 (isotype), BR 5020184245610 (isotype), HJB15834).

  • arrow_drop_downarrow_drop_upEtymology
    sagarae, honoring the work of Prof. Dr. Naohiko Sagara on the ecology of this fungus, which specifically grows in the vicinity of mammal latrines.
  • arrow_drop_downarrow_drop_upDiagnosis
    Similar to Hebeloma radicosum, with a long ‘rooting’ stipe, a membranous ring, an odor of marzipan, but differing by the possession of pleurocystidia. Known only from the Eastern Asia region.

Description

  • arrow_drop_downarrow_drop_upThresholds
Description of Hebeloma sagarae based on 8 collections
  • arrow_drop_downarrow_drop_upMacroscopic description
    Pileus: not recorded mm diameter; shape Not recorded; characters Not recorded; margin characters Not recorded; viscosity tacky when moist; colour variation Not recorded; colour at centre Not recorded.

    Lamellae: attachment Not recorded; maximum depth not recorded; number of complete lamellae not recorded; presence of tears Not recorded; white fimbriate edge often weak, occasionally absent.

    Cortina presence: Not recorded.

    Stipe: not recorded x not recorded {median} x not recorded {basal} mm; stipe Q not recorded; base shape Not recorded; floccosity Not recorded; rooting Not recorded; thick rhizoids at base Not recorded;

    Context: Texture firm; stipe interior Not recorded; stipe flesh discolouring Not recorded; slenderness measure not recorded; smell Not recorded; taste Not recorded.

    Spore deposit colour: Not recorded.

    Exsiccata characters: Not recorded.

  • arrow_drop_downarrow_drop_upMicroscopic description
    Spores: shape amygdaloid; colour in microscope yellow brown; guttules yes. papilla no; Spore Code: O3; P2 P3; D3.

    Basidia: 17–33 (34) x 6–8 μm; ave. Q 3.2–3.8; spore arrangement 4 spored;

    Cheilocystidia: main shape usually balloon-shaped or clavate-lageniform or clavate-ventricose, often cylindrical or ventricose, occasionally clavate, turbinate or utriform; special features observed often septa, short, irregular, geniculate or many collapsed in exsiccata, occasionally clamped septa, branching, rostrate or uniform; cheilocystidia ratios: A/M = 0.94–1.55; A/B = 0.86–1.31; B/M = 0.83–1.81.

    Pleurocystidia: often seen, occasionally none seen or only close to lamella edge.

    Ixocutis: epicutis thickness (measured from exsiccata) up to 320 μm; ixocutis hyphae width up to 7 μm; ixocutis hyphae encrustation no; shape of trama elements beneath subcutis isodiametric up to 20 μm wide.

    Caulocystidia: Similar to cheilocystidia but larger.

  • arrow_drop_downarrow_drop_upSpore measurements
  • arrow_drop_downarrow_drop_upCheilocystidia measurements
  • arrow_drop_downarrow_drop_upHabitat and distribution
    Hebeloma sagarae's preferred habitat appears to be woodland with nutrient-enriched (mole latrine) soil. Where only one possible associate was recorded, that associate has always been Quercus (family Fagaceae). We have additional records where Fagus and Castanopsis were recorded as possible associates, but in these cases a number of possible associates were mentioned. Fagaceae was the only recorded family. No growth habit has been recorded.

    According to our current collections, the species is found only in Asia-Temperate. On the continent, 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. (Nihonkai montane deciduous forests (62.5%), Taiheiyo evergreen forests (25.0%) and Nihonkai evergreen forests (12.5%) ecoregions). From collector information, it appears collections have been found only in the 1.4 Forest – Temperate IUCN habitat 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 Temperate Asia all our records are from Eastern Asia (Japan).

  • arrow_drop_downarrow_drop_upMolecular results
    All ITS sequences (GenBank MG367342.2–MG367347.2 and MT117086) obtained from basidiomes and mycorrhiza collected in the immediate vicinity of the holotype of H. sagarae were identical and belong to the same genotype. The ML results of ITS and MCM7 sequences were compatible. All the collections that we refer to as H. sagarae and on which our description is based, are morphologically and molecularly congruous. The sequences representing the species H. sagarae were monophyletic in relation to H. radicosum and the clade receives full support (99.5%). All molecular results fully support the monophyly of both H. radicosum and H. sagarae within H. sect. Myxocybe (99.3%).
  • arrow_drop_downarrow_drop_upCommentary
    Macroscopically H. radicosum and H. sagarae are very similar. Microscopically there are some differences that should be noted. Pleurocystidia have never been recorded for H. radicosum while they are present in all collections of H. sagarae that we have examined. While the average sizes of spores for these two species show considerable overlap (H. radicosum is in the range 8.3–9.7 x 5.2–5.9 μm as opposed to 7.6–8.9 × 5.1–5.8 μm for H. sagarae), the spores of H. radicosum are consistently more ornamented and more dextrinoid. Furthermore, while the cheilocystidia are similarly irregular in shape the average length of the cheilocystidia for H. sagarae have been recorded in the range 18–38 μm, while those for H. radicosum have been recorded in the range 37–57 μm. Mikami (2015) was the first to support the ectomycorrhizal lifestyle of H. sagarae with molecular data, suggesting that Quercus serrata might be its host. Mikami (2015) and Kasuya et al. (2017) showed and published in Japanese, that for one ectomycorrhizal root tip, collected in connection with a mycorrhizal system from underneath the holotype, the host tree could be determined as Q. serrata (GenBank acc. no. MG367361 and MG367364). From this ectomycorrhizal root (Kasuya B1358) a Hebeloma sp. (LSU; MG367357) was collected and sequenced. Based on a BLAST search against GenBank (23 Sep. 2019), this sequence differs 2–4 bp from other H. sagarae LSU sequences (MG367353–MG367356, MG367358– MG367360). It is likely that H. sagarae forms ectomycorrhizal relationships with species of Fagaceae (presumably members of Quercus, Castanopsis and Fagus) and possibly other deciduous trees, as does the true H. radicosum in Europe. Hebeloma sagarae is currently only known from the islands of Hokkaido and Honshu of Japan. It has been depicted and discussed under the name H. radicosum in various publications (e.g., Imazeki & Hongo 1987; Imazeki et al. 2011; Sagara 1978a; Sagara et al. 2000). As far as we are aware, and certainly with regard to the collections that we havestudied, it appears that H. radicosum, the only species that is very similar, does not occur in Japan and all collections that have previously been ascribed to the species H. radicosum from Japan are in fact H. sagarae. Within Japan, based on current knowledge, the only confusion that may arise, and has arisen (Sagara et al. 2000), is between H. sagarae and H. radicosoides, which also has a membranous ring and a long tapering ‘root’. However, H. radicosoides lacks the marzipan odor, has a yellowish pileus as opposed to the whitish pileus of H. sagarae (this color difference is well illustrated in Figs 5–9 of Sagara et al. 2000) and H. radicosoides also has less ornamented spores and the spores have a perispore that rarely loosens to form a sack around the spore. Hebeloma luchuense also has a long tapering root, but this species lacks a membranous veil, making it easily distinguishable from the two species discussed above. Also with a long root can be H. danicum (often recorded as H. spoliatum in the literature, e.g. Sagara 1978b, 1995; Sagara et al. 2000). These two species can be distinguished easily by examining the spores; the spores of H. danicum are strongly ornamented, with a strongly loosening perispore and are strongly dextrinoid, whereas the spores of H. luchuense are weakly ornamented, have a perispore that hardly loosens, if at all, and are almost indextrinoid. Extensive studies by Sagara (1976, 1978a, 1980, 1981, 1989, 1995, 1998, 1999), Sagara & Fukasawa (2014), Sagara et al. (1985, 1989, 1993a, 2000, 2006, 2008) and Nakai et al. (2016) have shown the link between H. sagarae and the latrines (close to the nests) of moles and shrews, as well as the link between occurrence of H. radicosum and the occurrence of moles or wood mice latrines. It may well be that the two species of H. sect. Myxocybe only grow when a large additional input of nitrogenous material, from for example animal latrines, occurs in the presence of suitable ectomycorrhizal partners. Sagara et al. (2000) also report on the chemical production of the ‘marzipan’ odor present in H. sagarae and H. radicosum. It appears that they contain 1-octen-3-ol, phenylacetaldehyde and N-formylaniline at high levels, and that their characteristic odor is yielded when 1-octen-3-ol and phenylacetaldehyde are mixed.
Geographic distribution
Phenology
  • arrow_drop_downarrow_drop_upAdditional cited collections

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