Full name: Hebeloma macrosporum Velen. (1920)
Published: Ceske Houby: 398 (1919) ["1920"]
Taxonomic status: Heterotypic synonym of H. crustuliniforme
Types: CZECH REPUBLIC: Mnichovice (49.5612°N, 14.4245°E, alt. approx. 590 m a.s.l.), Aug. 1915, J. Velenovsky (Lectotype. herbarium acc. no. PRC B380, HJB1000241). Lectotype designated by Beker et al., Hebeloma (Fr.) P. Kumm.: (2016) page 610 (MBT202536).

The collection at PRC dated Aug.1915 appears to represent original material, as mentioned in the protologue, and was designated as lectotype.

Original diagnosis: Pileo 4-5 cm diam., obtuse convexo, subcarnoso, margine diu anguste involuto et albo-tomentoso, udo viscido, sicco levi, sordide alutaceo, quasi albo-pruinoso et apud marginem fere albo. Stipite pilei diam. longiori, 6-8 mm crasso, candido, sericeo-fibrilloso-lucido, apice albo-furfuraceo, elastico, solido, basi haud incrassato. Lamellis confertissimis, tenuibus haud latis, decumbentibus, postice emarginatis, argillaceis, acie albis et dentatis. Sporis impariter magnis, nonnullis permagnis (15-18 μm), late amygdaliformibus. Cystidiis numerosis, longe filiformibus, apice rotundatis. In declivitate calida occidentali in foliis Robiniae pseudacaciae supra viam aerariam prope Mencice augusto quotannis gregarium. Formis parvis Hebelomatis crustuliniformis simillima.

English translation: Pileus 4–5 cm diam., bluntly convex, thin-fleshed, margin long narrowly involute and white tomentose, viscid when moist, smooth when dry, sordid pale brown, quasi white pruinose and at margin truly white. Stipe length longer than diameter of pileus, 6–8 mm thick, white, shining silky fibrillose, white furfuraceous at apex, elastic, solid, base not broadened. Lamellae very crowded, thin, not broad, prostrate, emarginate, pale brown, with white, enticulate edge. Spores of different sizes, rather large (15–18 μm), broadly amygdaloid. Cystidia abundant, long-filiform, with rounded apex. On a thermophilic, westerly slope among leaves of Robinia pseudoacacia along a coppermine road near Mencice every year in groups in August. Resembles a small form of Hebeloma crustuliniforme.

Commentary: The ‘original diagnosis’ above is the translation into Latin from the original Czech by Pilat, Opera Bot. Čechica 6: 138 (1948). While we have not been able to amplify DNA from the material, we have been able to make a morphological examination. The basidiome is still entire and one can count some 80 full length lamellae. Coupling this with the spores and cheilocystidia indicates this material is from Hebeloma subsect. Crustuliniformia, in the crustuliniforme-complex. The spores are on average 10.8 × 6.1 μm, somewhat smaller than indicated in the protologue. The cheilocystidium apex is relatively small for this complex, 6.4 μm. These characters indicate that this taxon is: = Hebeloma crustuliniforme (Bull.) Quél.