Full name: Hebeloma nigricans Velen. (1920)
Published: Ceske Houby: 393 (1919) ["1920"]
Taxonomic status: Heterotypic synonym of H. laterinum
Types: Not found in PRC. Described from the Czech Republic, Radiotin, Aug. 1918, in Picea forest.

Original diagnosis: Pileo 3-5 cm diam., obtuse campanulato, levi, glabro, ad marginem diu involutum albo, albido-alutaceo, udo viscido. Stipite longo, recto, relativiter crasso (1 cm), basi leniter inflato, albo, sed fere omni conferte granulose albo-pulverulento, pressione nigricanti. Lamellis confertis, late adnatis, albis, tum ferrugineis usque fuscescentibus, acie subtiliter denticulatis. Sporis fuscis, inaequilateralibus, apicibus ambobus acutatis, 10 μm. Cystidiis numerosis, longis, recte filiformibus, apice capitatis et rotundatis. In piceto loco humoso solo calcareo in valle Radotinensi augusto 1918. Hebelomati clavicepti Fr. affine, sed tamen sat differt. Praecipue stipes nigricans insignis est.

English translation: Pileus 3–5 cm diam., bluntly campanulate, smooth, glabrous, long with involute, white margin, whitish-yellowish, viscid when moist. Stipe long, straight, relatively thick (1 cm), slightly inflated at base, white, but almost entirely and densely white granulose-pulverulent, blackening when handled. Lamellae crowded, broadly adnate, white then rusty brown to sordid dark brown, edge delicately denticulate. Spores dark brown, inequilateral, attenuate towards both ends, 10 μm. Cystidia abundant, long, straight, filiform, with rounded, capitate apex. In Picea forest on humus-rich calcareous soil in the Radotinensi valley August 1918. Close to Hebeloma claviceps Fr. but rather different. Especially the blackening stipe is important.

Commentary: The ‘original diagnosis’ above is the translation into Latin from the original Czech by Pilat, Opera Bot. Čechica 6: 135 (1948). Unfortunately, the material under this name preserved in alcohol/formaldehyde in PRC in Bottle 78 does not correspond with the protologue, but it agrees with H. odoratum which originally was stored in the same bottle (Bottle 78). However, judging from the protologue, we can be confident that H. nigricans: = Hebeloma laterinum (Batsch) Vesterh.