Hebeloma incarnatulum (Photo: D. Laber)

Taxonomy

Types: UNITED STATES: Michigan: Mud Lake Bog west of Whitmore Lake, Washtenaw (approx. 42.42°N, 83.76°W, alt. approx. 275 m a.s.l.) on boggy, mossy soil in woodland bog under Larix sp., 14 Oct. 1961, A.H. Smith (64680) (Holotype. herbarium acc. no. MICH 10752, HJB1000136).

Heterotypic synonyms:

• Hebeloma bryogenes Vesterh., Windahlia 20: 55 (1993)
• Hebeloma stenocystis J. Favre, Catalogue desriptif des Chamigons Superieurs de la Zone Subalpine du Parc National Suisse 6 (Neue Folge): 496 (1960)
• Hebeloma calvinii Hesler & A.H. Sm. [as "calvini"], Sydowia 37: 279 (1984)
• Hebeloma crustuliniforme f. sphagnophilum Kauffman, The Agaricaceae of Michigan: 477 (1918)

• arrow_drop_downarrow_drop_upEtymology
  A derivative from the Latin adjectival base incarnatus– flesh-coloured, and the diminutive suffix –ulus meaning ‘slightly flesh-coloured’. The name refers to the pileus colour.

• arrow_drop_downarrow_drop_upOriginal diagnosis
  Pileus 3–5 (8) cm latus, late convexus vel leviter umbonatus, viscidus, glaber, pallide vinaceobrunneus, ad marginem sordide pallidus. Sapor raphanius demum amarus; odor ± raphanius. Lamellae angustae, confertae, adnatae demum subdecurrentes. Stipe 5–9 cm longus, 5–10 (12) mm crassus, subbulbosus, sursum aequalis, albidus demum sordidus, sursum furfuraceus, substriatus. Velum nullum. Sporae 9–12 x 5.5–7 (7.5) μm, dextrinoideae. Basidia tetraspora. Pleurocystidia nulla. Cheilocystidia (37) 50–74 x 4–6 (8) μm, elongate clavata, anguste, fusoideo-ventricosa, subcylindrica, etc. Specimen typicum in Herb. Univ. Mich. Oct. 4, 1961, Sm-64680.

• arrow_drop_downarrow_drop_upEnglish translation
  Pileus 3–5 (8) cm broad, broadly convex or slightly umbonate, viscid, glabrous, pale vinaceous brown, dull light brown at margin. Taste raphanoid, finally bitter; odour more or less raphanoid. Lamellae narrow, crowded, adnate then subdecurrent. Stipe 5–9 cm long, 5–10 (12) mm thick, subbulbous, cylindrical above, whitish then drab, scurfy at the apex, substriate. Veil absent. Spores 9–12 × 5.5–7 (7.5) μm, dextrinoid. Basidia four-spored. Pleurocystidia absent. Cheilocystidia (37) 50–74 × 4–6 (8) μm long-clavate, narrow, fusoid-ventricose, subcylindrical, etc. Type specimen in Herb. Univ. Mich. Oct. 4, 1961, Sm-64680.

Description

Description of Hebeloma incarnatulum based on 103 collections

• arrow_drop_downarrow_drop_upMacroscopic description
  Pileus: (14) 24–55 (70) mm diameter; shape often umbonate, occasionally convex or weakly umbonate, rarely broadly umbonate, umbilicate or strongly umbonate; characters occasionally hygrophanous or spotting; margin characters usually smooth, rarely involute, crenulate or wavy; viscosity tacky when moist; colour variation often unicolour, occasionally two color; colour at centre occasionally yellowish brown, rarely clay-buff, dark pinkish buff, ochraceous, cinnamon, brownish olive, umber, brick, warm buff or cream.

  Lamellae: attachment often emarginate, occasionally adnate, rarely decurrent tooth; maximum depth 2–5 mm; number of complete lamellae 52–66; presence of tears often visible with naked eye, occasionally absent, rarely visible with x10 lens; white fimbriate edge often present, occasionally very strong, rarely weak.

  Cortina presence: no.

  Stipe: (29) 52–112 (130) x (4) 6–9 (12) {median} x (5) 8–17 (29) {basal} mm; stipe Q 3.8–21.7; base shape usually bulbous, rarely clavate, cylindrical or subbulbous; floccosity occasionally pruinose, pruinose at apex or velute, rarely fibrillose, floccose at apex, floccose or weakly floccose; rooting usually no, rarely yes; thick rhizoids at base usually absent, occasionally present;

  Context: Texture firm; stipe interior usually hollow, occasionally superior wick or stuffed; stipe flesh discolouring often no, occasionally yes, rarely weak; slenderness measure 11.8–38.1; smell often raphanoid, rarely weakly raphanoid, strongly raphanoid or cocoa; taste often raphanoid, bitter or mild where recorded.

  Spore deposit colour: often brownish olive, occasionally umber or cinnamon.

  Exsiccata characters: rarely dark, fragile, hard or shiny.

• arrow_drop_downarrow_drop_upMicroscopic description
  Spores: shape amygdaloid, rarely limoniform; colour in microscope occasionally brown, yellow brown, grey yellow or very pale; guttules variable. papilla often no, occasionally weak; Spore Code: O1 O2; P0 (P1); D3 D4.

  Basidia: (20) 21–32 x 6–9 (10) μm; ave. Q 3.0–4.1; spore arrangement 4 spored;

  Cheilocystidia: main shape gently clavate, often clavate, occasionally lageniform, cylindrical, ventricose or clavate-lageniform or clavate-ventricose, rarely capitate-stipitate or tapering; special features observed often bifurcate, occasionally septa, rarely clamped septa, conglutinate, geniculate, many collapsed in exsiccata or narrow; cheilocystidia ratios: A/M = 1.12–1.57; A/B = 0.91–1.44; B/M = 1.03–1.34.

  Pleurocystidia: none seen.

  Ixocutis: epicutis thickness (measured from exsiccata) up to 200 μm; ixocutis hyphae width up to 8 μm; ixocutis hyphae encrustation yes; shape of trama elements beneath subcutis usually ellipsoid or thickly sausage-shaped, occasionally isodiametric or cylindrical up to 22 μm wide.

  Caulocystidia: Similar to cheilocystidia but larger, up to 150 μm.

• arrow_drop_downarrow_drop_upSpore measurements

• arrow_drop_downarrow_drop_upCheilocystidia measurements

• arrow_drop_downarrow_drop_upHabitat and distribution
  Hebeloma incarnatulum's preferred substrate appears to be mossy soil. Where only one possible associate was recorded, the most commonly recorded associate was Picea (56.6%) but Pinus (20.8%), Abies (7.5%), Larix (5.7%), Tsuga (5.7%), Betula (1.9%) and Pseudotsuga (1.9%) were also recorded. In these cases the most commonly recorded family was Pinaceae (98.5%). We have additional records where Alnus (3.5%), Populus (3.5%), Fagus (1.2%) and Quercus (1.2%) were recorded as possible associates, but in these cases a number of possible associates were mentioned. Overall the most commonly recorded families are Pinaceae (89.5%) and Betulaceae (8.1%) The growth habit of our collections was often scattered, occasionally gregarious and rarely solitary.

  According to our current data, the species is found on multiple continents with collections found in Northern America (57.6%) and Europe (42.4%). 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 (38.5%), boreal forests/taiga (35.4%), temperate conifer forests (13.5%) and unknown biome (10.4%), specifically including the ecoregions: Western European broadleaf forests (14.6%), Eastern Canadian forests (13.5%), Scandinavian and Russian taiga (10.4%) and Unknown region (10.4%). From collector information, it appears collections have been found in the 1.1 Forest – Boreal (55.3%) and 1.4 Forest – Temperate (30.6%) 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 Eastern Canada (Newfoundland and Labrador, Quebec and Ontario), Western Canada (British Columbia and Alberta), Subarctic America (Nunavut and Alaska), Northwestern U.S.A. (Washington), North-central U.S.A. (Minnesota and Wisconsin) and Northeastern U.S.A. (Michigan).

  Within Europe we have records from the Centre (Germany, Poland and Switzerland), the North (Finland, Norway and Denmark), the Southeast (Italy) and Eastern Europe (Estonia). Specimens have been collected from 46.1°N to 69.6°N.

• arrow_drop_downarrow_drop_upMolecular results
  The ITS is the only locus among the loci tested which does not separate H. incarnatulum from the other species of the velutipes-complex. The synonymization of H. bryogenes with H. incarnatulum is supported by ITS, V6 and V9 sequences. Some H. velutipes ITS sequences are included in the same clade as those of H. incarnatulum, thus, based on ITS, it is not always possible to distinguish between the two species.

• arrow_drop_downarrow_drop_upCommentary
  Given the shape of its cheilocystidia together with the rather strongly dextrinoid spores, H. incarnatulum clearly belongs to H. sect. Velutipes and we regard t as a member of the velutipes-complex. Within this section, and based on the cheilocystidia, it could be confused with H. aestivale, H. leucosarx or H. velutipes. Its spores at most weakly ornamented (O1-2) and with perispore at most slightly loosening in a few spores (P0–1) distinguishes it from H. aestivale, which is also macroscopically very different but has similar cheilocystidia. Its cheilocystidium apex, on average at most 6.5 μm, separates it from H. leucosarx and H. velutipes, which it most resembles macroscopically. At the time of publication of Beker et al. (2016), we had not had the opportunity to study all North American type material and, hence, have felt it safer to restrict ourselves to European or North African names as far as that text was concerned. While we could not, at thathad stage in our research, rule out that there may exist other North American names that might have precedence over the name H. incarnatulum, we did have sufficient evidence, both molecular and morphological, that this is the same taxon as H. bryogenes and the name H. incarnatulum certainly has precedence. Therefore, in this instance, we adopted the name H. incarnatulum for this taxon and the line drawings, holotype description and holotype microscopic pictures come from the holotype collection of H. incarnatulum, rather than the first European published name for this taxon, which we believe to be H. bryogenes. The type collection of H. bryogenes has been included in our cited collections on which the species description is based. Also included in the collections on which our species description is based is the original collection of H. stenocystis, on which Favre based his species (Favre 1960), albeit it was invalid as no type collection was designated by the author. We have examined this material, both morphologically and molecularly, and we have no doubt that it represents this taxon. Quadraccia (1988) tried to correct the invalid publication of H. stenocystis by publishing a new description of H. stenocystis, with a new collection as holotype, and quoted Favre’s collection as paratype. Our research has shown that Quadraccia’s new holotype is conspecific with H. leucosarx and this is discussed further in the comments on that species. Hebeloma incarnatulum is one of the few Hebeloma spp. that can be named with reasonable confidence in the field. Given the slender form of the basidiome and the bulbous base with the habitat (always being found with conifer trees in Sphagnum) the only confusion should be with H. leucosarx, which is usually less slender and with a wider pileus, less conical in appearance.

Geographic distribution

Phenology

• arrow_drop_downarrow_drop_upAdditional cited collections

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