Full name: Hebeloma dunense L. Corb. & R. Heim (1929)
Published: Mém. Soc. Sci. Nat. Math. Cherbourg 40: 166 (1929)
Taxonomic status: Heterotypic synonym of H. velatum
Types: FRANCE: Manche, Dunes de Vasteville (approx. 49.5953°N, 1.7719°W, alt. approx. 5 m a.s.l.) on sandy soil in dune under Salix repens, 22 May 1926, R. Corbiere (Lectotype. herbarium acc. no. CHE020422, HJB13012). Lectotype designated by Beker et al., Hebeloma (Fr.) P. Kumm.: (2016) page 125 (MBT202544).

Homotypic synonyms: Hebelomatis dunense (L. Corb. & R. Heim) Locq. (1979) ["1977"]

Original diagnosis: Chapeau de 1 à 3 cm. de diamètre. D’abord fortement convexe ou même hémisphérique. À marge enroulé nettement cortiné au début, convexe ou largement umboné chez l’adulte, parfois tardivement aplani mais très rarement déprimé, légèrement fibrilleux-soyeux sur les bords qui sont quelquefois relevés et fendillés, glabre, toujours lisse, roux-purpurin ou ochre-roux, plus pâle sur les bords avec le centre plus foncé et comme vernissé. Cortine fibrillo-soyeuse, blanchâtre et très nette au début, persistent ensuite sur le pied et même parfois sur la marge, se colorant en roux par les spores tombées. Pied de 1.5 á 3 cm. de hauteur, de 3 á 6 mm. de diamètre, cylindrique, parfois irrégulier ou courbé, fibrilleux, finement strié, plein au début, souvent creux á la fin, jaune paille ou blanchâtre, blanc au sommet. Lamelles adnées, légèrement decurrentes par la dent, assez serrées, minces non ventrues, d’abord ocre pâle, puis ocracées, avex la marge plus pâle au début mais purpurine sur les échantillons àgés. Chair ferme, hygrophane, crème, inodore, á saveur douce rappellant celle du champignon de couche. Spores ovoides, à depression ventrale peu marquée et non médiane, á hile net, peu colorées (ocre pâle vues isolément, ocre-roux vues en tas), sans pore germinatif, de 10–12,5 sur 6–7,5 μm, paraissant lisses main finement ponctuées á l’immersion. Basides cylindrico-claviformes, de 30 sur 7–9 μm environ, tetraspores, munies de stérigmates longs et arqués. Pas de cystides vraies, ni même de poils cystidiformes en touffes et très proéminentes, comme chez les nombreux Inocybe, mais des poils localisés á la tranche des lamelles, d’environ 30 μm de long sur 11–12 μm, renflés et souvent étranglés dans le haut. Sous hyménium celluleux. Trame à grosses cellules cylindriques, longues d’environ 50 μm sur 10–12 μm de large. Cette espèce remarquable, tout à fait arénicole, vient chaque printemps, de fin avril à fin mai, sur le sable encore humide de fonds de civettes dans les dunes de Bivelle, Vasteville, Héauville, près de Cherbourg, oú elle est rare et bien localisée.

English translation: Pileus from 1–3 cm diam., strongly convex at first or even hemispherical with inrolled margin, distinctly cortinate in the beginning, convex or broadly umbonate in mature state, sometimes finally applanate, but very rarely depressed, slightly fibrillose-silky at margin, which sometimes is uplifted and cracked, glabrous, always smooth, reddish purple or reddish ochre, much paler towards margin with darker, as if lacquered, centre. Cortina fibrillose-silky, whitish and very distinct at first, persistent on the stipe and even sometimes on the margin of the pileus, turning brown from the spores. Stipe 1.5–3 cm long, 3–6 mm wide, cylindrical, sometimes irregular or curved, fibrillose, finely striate, solid at first, often hollow at the end, pale yellow or whitish, white at apex. Lamellae adnate, slightly decurrent with tooth, rather crowded, thin, not ventricose, pale ochre at first, then ochre with much paler edge, which turns purple in aged specimens. Context firm, hygrophanous, cream-coloured, without odour, with sweet taste, reminiscent of that of cultivated mushrooms (Agaricus spp). Spores ovoid, with poorly marked and not median ventral depression, with distinct apiculus, little coloured (pale ochre when seen isolated, reddish ochre in mass), without germ pore, 10–12.5 × 6–7.5 μm, appearing smooth but finely punctate under immersion. Basidia cylindrical-claviform, about 30 × 7–9 μm, with long and curved sterigmata. No true cystidia, not even with prominent cystidiform hairs in bundles like in many Inocybe, but with marginal hairs along the edge of the lamellae, about 30 μm long and 11–12 μm wide, swollen and sometimes strangled above. Subhymenium cellular. Trama made up of large, cylindrical cells, about 50 × 10–12 μm. This remarkable species, strictly arenicolous, appears every spring, from the end of April to the end of May, on the still moist sands in the basins of the dunes of Bivelle, Vasteville, Héauville, near Cherbourg where it is rare and very localized.

Commentary: With the persistent presence of a cortina and the lageniform or ventricose cheilocystidia, this taxon clearly belongs in H. section Hebeloma. Within this section, with primarily indextrinoid or indistinctly (but clearly) dextrinoid ellipsoid spores, although some may be amygdaloid or ovoid, and spores greater than 10 μm long and 6 μm wide and growing with Salicaceae, this species can only be confused with H. psammophilum and H. marginatulum. The former taxon only occurs in dunes and has a much more robust stature than H. dunense, as well as more full length lamellae (L greater than 50). Hebeloma marginatulum only occurs in alpine and arctic habitats and in this habitat separating this taxon from H. dunense, using morphological characters, can be problematic. The best way to separate these taxa morphologically is using the fact that the spores of H. marginatulum are very indistinctly ornamented, the ornamentation being difficult to see even at high magnification, and the spores also appear completely indextrinoid, whereas H. dunense spores always have some clear ornamentation at high magnification and while indistinctly dextrinoid, usually show some reaction. It also appears from our studies under the light microscope that the spores of H. dunense are more yellow, while those of H. marginatulum have a greyish tinge. Interestingly, Besson & Bruchet (1972) appear to have found a marked difference between the spores of these two taxa. Although their findings with regard to the ornamentation and dextrinoidity are not totally in-line with our findings, we note below their remarks: “Deux autres espèces s’écartent par contre beaucoup plus nettement de ce groupe: ce sont H. marginatulum et surtout H. collariatum [H. dunense]. Ces deux champignons possèdes des spores ovoïdes-amygdalaires, a paroi assez épaisse, ferme et réfringente, soit tout au plus ruguleuse, a ornementation toujours assez saillante, ce qui est assez exceptionnel chez ce type de spores (H. collariatum). Par rapport aux spores des espèces du premier groupe, celles-ci présentent un gonflement membranaire constant dans l’acide acétique, bien qu’il puisse être extrêmement faible et difficile à déceler (H. marginatulum), et une réaction avec l’iode un peu plus marquée. D’autre part, chez H. collariatum, comme chez la plupart des espèces du deuxième groupe, le traitement potassique a chaud, qui décolore les spores et entraine la disparition des couches III, IV et V, ne détruit jamais complètement la couche II qui peut être alors révélée par gonflement”. It is only recently that we became aware that H. dunense also occurs in arctic and alpine areas and we suspect that previously many collections of this taxon from those habitats have been recorded as H. marginatulum. There are some marked differences between collections of H. dunense in arctic and alpine habitats from those in dunes and other more lowland habitats (including slag-heaps). The arctic and alpine collections tend to be less slender with shorter stipe, presumably as a result of the conditions they must endure in that habitat. It may be that we should be differentiating more than one species here, but this will need further research, and further evidence of speciation, before a reliable decision can be made. This taxon has been described as novel numerous times, as: H. collariatum, H. aprile, H. psammicola, H. claviceps f. nigrescens, H. xerophilum, H. remyi. In the case of H. remyi this is H. remyi Bruchet ex Quadr. Quadraccia chose to try and legitimise Bruchet’s H. remyi, which he believed was invalid, but unfortunately chose material for the type which was a different species from that intended by Bruchet. Bruchet, when describing H. collariatum, emphasised the presence of a strongly developed veil forming a persistent collar zone on the stipe as being characteristic for this species. This character is, however, very variable and in some collections the veil was not easily observable even on very young specimens. In the case of a collection with no visible sign of a cortina, it is the presence of a fibrillose stipe that usually indicates that a cortina had been present. This has been studied morphologically and molecularly. The lectotype is: = H. velatum.

Full name: Hebelomatis dunense (L. Corb. & R. Heim) Locq. (1979) ["1977"]
Published: Flore Mycologique Vol III - Text. Cortinariales A: 130 (1979) ["1977"]
Taxonomic status: Heterotypic synonym of H. velatum
Notes: Nom. inval. (Art. 41.5).

Types: FRANCE: Manche, Dunes de Vasteville (approx. 49.5953°N, 1.7719°W, alt. approx. 5 m a.s.l.) on sandy soil in dune under Salix repens, 22 May 1926, R. Corbiere (Lectotype. herbarium acc. no. CHE020422, HJB13012). Lectotype designated by Beker et al., Hebeloma (Fr.) P. Kumm.: (2016) page 125 (MBT202544).

Homotypic synonym of: Hebeloma dunense L. Corb. & R. Heim (1929)

Commentary: See Hebeloma dunense L. Corb. & R. Heim.