Full name: Hebeloma hygrophilum Poumarat & Corriol (2016)
Published: Hebeloma (Fr.) P. Kumm.: 138 (2016)
Taxonomic status: Heterotypic synonym of H. paludicola
Types: FRANCE: Ariege, Querigut, Foret des Ares (Chemin du lac) (approx. 42.7047°N, 2.1075°E, alt. approx. 1250 m a.s.l.) on boggy, calcareous, mossy soil in subalpine willow thicket under Salix aurita, 25 Sep. 2008, S. Poumarat, G. Corriol (SGP 08 09 58) (Holotype. herbarium acc. no. BBF GC08092503 (holotype), BR 5020184128654 (isotype), HJB12966; Isotype. HJB12963).

Diagnosis: Hebeloma hygrophilum has a persisting cortina and lageniform or ventricose cheilocystidia and is, therefore, a member of H. section Hebeloma. Within this section, it can be differentiated on the basis of the amygdaloid, limoniform and sometimes fusoid spores, distinctly to rather strongly dextrinoid, and on average less than 7 µm wide, the number of full length lamellae less than 40 and the habitat, which is primarily boreal and not arctic or alpine as for H. fuscatum. Hebeloma hygrophilum usually occurs in wet areas, among Sphagnum with Salix.

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, it can be differentiated on the basis of the amygdaloid, limoniform and sometimes fusoid spores, distinctly to rather strongly dextrinoid less than 15 μm long and less than 7 μm wide, the number of lamellae less than 40 and the habitat, not arctic or alpine but primarily boreal, usually in wet areas with Salix and normally also with Sphagnum. Hebeloma hygrophilum is morphologically similar to H. clavulipes, H. fuscatum and H. nigellum. Hebeloma fuscatum is strictly arctic or alpine. Hebeloma nigellum also grows in non arctic or alpine areas but it can be differentiated quite easily on account of its wider spores (at least 7 μm wide) but also on its macroscopic appearance which is quite hard to define but clear. Hebeloma clavulipes can be separated on the greater number of lamellae (L at least 40). Poumarat & Corriol (2009) recognized this as a distinct species and published it as an “ad int.” awaiting further molecular studies to be sure of its status. They believed that it was the same taxon as H. remyi sensu Bruchet and even in the title of the article mention “H. hygrophilum ad int. (= H. remyi ss. Bruchet non Quadraccia)”. We now believe that H. remyi ss. Bruchet is synonymous with H. clavulipes and distinct from H. hygrophilum. The name they chose for this taxon emphasizes their recognition of its favoured habitat.