Full name: Hebeloma caespitosum Velen. (1920)
Published: Ceske Houby: 389 (1919) ["1920"]
Taxonomic status: Heterotypic synonym of H. mesophaeum
Types: CZECH REPUBLIC: Opocno (50.16°N, 16.06°E, alt. approx. 455 m a.s.l.), Aug. 1915, Poncova, det: J. Velenovsky (Lectotype. herbarium acc. no. PRC B131, HJB1000234). Lectotype designated by Beker et al., Hebeloma (Fr.) P. Kumm.: (2016) page 577 (MBT251114).

The material selected as lectotype is from one of the two localities mentioned in the protologue and was collected five years before the species was described, so meets the criterion to be designated as lectotype.

Original diagnosis: Dense caespitosum vel etiam solitarium. Pileo 3-4 cm diam., obtuse humiliter convexo tum explanato, saepe umbonato, sicco, haud lucido, ahygrophano, albido tincto alutaceo usque griseo-fusco, haud lucido, glabro, iuventute cortina abundanti (quae in stipite anulum arachnoideum relinquit), cum stipite coniuncto. Stipite longissimo, deorsum vix leniter incrassato, 3-5 mm crasso, firme elastico, solido, albido, longitudinaliter fimbriato-fibrilloso, tactu brunnescenti, apice granulato-furfuraceo. Lamellis confertis, sordide pallidis, tum carneo-ferrugineis, latis, adnatis, acie albis et subtiliter denticulatis. Carne alba, odore debili. Sporis late ellipsoideis, sordide fuscis, 8-12 μm. Cystidiis long filiformibus, obtuse capitatis.

English translation: Solitary or in large groups. Pileus 3–4 cm broad, bluntly convex, expanding, often umbonate, dry, not shiny, not hygrophanous, white with yellowish tinges then greyish-brown, glabrous, young with abundant cortina (that remains on the stipe as an arachnoid annulus), continuous with stipe. Stipe very long, slightly broadened towards base, 3–5 mm wide, firm, elastic, solid, white, longitudinally fibrillose striate, turning brown when handled, granulose-flocculose at apex. Lamellae crowded, sordid, pale, then flesh-coloured to reddish brown, broad, adnate, with white, subtly crenulate edge. Context white, odour weak. Spores broadly ellipsoid, sordid greyish brown, 8–12 μm. Cystidia long, filiform, bluntly capitate.

Commentary: The ‘original diagnosis’ above is the translation into Latin from the original Czech by Pilat, Opera Bot. Čechica 6: 134 (1948). Unfortunately, we were not able to amplify DNA from the lectotype material. However, morphological studies of the lectotype reveal spores corresponding to either Hebeloma mesophaeum or H. subtortum. The description, and the habitat, indicate that H. mesophaeum is far more likely. Hence: = Hebeloma mesophaeum (Pers.) Quél.