Full name: Hebeloma sordidum Maire (1914)
Published: Bulletin trimestriel de la Société Mycologique de France 30 (2): 212 (1914)
Taxonomic status: Heterotypic synonym of H. subtortum
Types: ALGERIA: Chrea (approx. 36.43°N, 2.87°E, alt. approx. 1500 m a.s.l.) under Cedrus sp., 26 Nov. 1911, R. Maire (Lectotype. held at herbarium MPU, HJB1000105). Lectotype designated by Quadraccia, Mycotaxon 30: (1987) page 306.

Original diagnosis: Carpophoris gregariis, non hygrophanis; odore raphanoideo; carne miti, in stipites dilute fulvescente; stipites 4-8 x 0.6-0.8 cm, subaequali, cavo, fibroso-carnoso, fragili. Sicco-fibrilloso, apice furfuraceo, ex albido fulvescente, apice albo, basi demum fuscescente, Cortina albida in margine pilei et in stipites diu persistente: pileo 3-7 cm e campanulato-convexo expanso, subumbonato, sat tenui, carnoso-fragili, cuticula adnata, subviscoso, glabro, ochraceo-fuscescente, fibrillis innatis albo-velato, margine incurvo, albo-tomentello; lamellis ex arcuato planis, tenuibus, confertis, latis, ex albido argillaceis, late adnatis, leviter emarginatis, acie albo-flocculosa; lamellis attenuates; sporis in cumulo ochraceo-olivaceis, s.m. luteo-olivascentibus, ellipsoideo-subamygdaliformibus, 1-pluriguttulatis, sublaevibus, 8-10 x 4-6 μm; cystidiis nullis; pilis aciei flexuosis, subfilamentosis; basidiis 4-sporis, subcylindraceis, 30-33 x 6-8 μm.

English translation: Basidiomes in groups, not hygrophanous, with raphanoid odour, mild context, turning diluted brown in stipe; stipe 40–60 × 0.6–0.8 cm, subequal, hollow, fibrous-fleshy, fragile, dry-fibrillose, with furfuraceous apex, white then turning brown, apex white, base later brown. Cortina white at margin of pileus and on the stipe long persisting: pileus 3–7 cm, campanulate expanding convex, subumbonate, quite thin, fleshy-fragile, with adnate cuticle, subviscid, glabrous, ochre then turning brown with adnate whitish veil remnants, with incurved, white hairy margin; lamellae arcuate then plane, thin, crowded, broad, white then clay-coloured, roadly adnate, slightly emarginate, with white flocculose edge, lamellulae attenuate; spores in mass ochre-olivaceous, under microscope yellow-olivaceous, ellipsoid to subamygdaloid, uni- to pluri-guttulate, almost smooth, 8–10 × 4–6 μm; cystidia absent; marginal hairs flexuous, subfilamentous; basidia four-spored, subcylindrical, 30–33 × 6–8 μm.

Commentary: Judging from the protologue and the painting that Maire did of his collection, and our studies of the lectotype, we have no doubt that this taxon is: = Hebeloma subtortum P. Karst.

Full name: Hebeloma sordidum var. microsporum Saini & Atri (1985)
Published: Geobios New Reports 4: 2 (1985)
Taxonomic status: Heterotypic synonym of H. nanum
Types: INDIA: Himachal Pradesh, Summer Hill, Shimla (approx. 31.1146°N, 77.1399°E, alt. approx. 1985 m a.s.l.) on soil and litter in montane, subtropical woodland under Cedrus deodara, 28 Aug. 1979, N.S. Atri (NSA23) (Holotype. herbarium acc. no. PUN 277, HJB1000592; Isotype. herbarium acc. no. F C0238638F, HJB1000394).

Diagnosis: Carpophoris usque 6.5 cm altis. Pileo usque 6 cm Jato, obtuso, convexo, brunneolo aurantiis (5C4). Lamellis adnexis, brunneolo aurantiis (5C3) in immuturis carpophoris ac brunneolo aurantiis (5C4) in maturis carpophoris, acie fimbriatis. Stipite usque 5.5 x 1.5 cm, cylinderaceo, aequali, flavido albido (1A2), brunneolo in aridus carpophoris. Sporis 7.6-8.8 (9) x 3.6-5 (5.5) µm, fusiformis , punctatis. Chei!ocystidiis (16)-24-52.5 x 3.5-7 µm, numerosis.

Commentary: Based on both morphology and ITS sequence, this is: = Hebeloma nanum Velen.