Revisions to the Gliophorus irrigatus complex (Agaricales, Hygrophoraceae, Gliophorus, section Unguinosae) including a new waxcap, G. alboviscidus, from the UK but detected globally via soil eDNA, two new species from eastern North America, G. fumosus and G. parafumosus, plus a new species, G. calunus, and a new combination of Hygrophorus subaromaticus in Gliophorus from western North America.

Here we report the discovery of four new agaricoid fungi in the Gliophorus irrigatus complex of the family Hygrophoraceae. Gliophorus alboviscidus sp. nov. from the UK is morphologically identical to the European G. irrigatus (which we neotypify), except that its basidiome is white or pale Buff coloured vs brownish grey. Two new species from eastern North America, Gliophorus fumosus sp. nov. (provisional name Gliophorus sp. irrigatus-IN01), and Gliophorus parafumosus sp. nov (previously labelled G. irrigatus) resemble G. irrigatus s.s. in colour and morphology but their distributions are restricted to North America. Phylogenetic reconstruction revealed that these samples form distinct clades, with >10% ITS sequence divergence from European G. irrigatus s.s. and from each other. Though G. alboviscidus sp. nov. is currently known only from two locations in the UK, searches for related sequences from eDNA (environmental DNA) sequence repositories (UNITE/GlobalFungi) suggested that this species is more widely distributed in Eurasia. G. fumosus and G. parafumosus sequences from eastern North America were divergent from both European G. irrigatus and G. alboviscidus; both were more closely related to another species with a strong odour and white/Buff basidiomes from northwestern North America, Hygrophorus subaromaticus for which we sequenced the holotype and recombine in the genus Gliophorus. We also describe a new species from northwestern North America, G. calunus sp. nov. (provisional name Gliophorus sp. irrigatus-CA01), based on vouchered specimens photographed and sequenced by an paraprofessional group, CA FUNDIS. We highlight the importance of citizen scientist groups and paraprofessionals in documenting macrofungal species and their distributions via databases such as iNaturalist, Mushroom Observer and MycoMap. Further, we discuss reasons eDNA distributions are often larger than known distributions of basidiomes, including G. alboviscidus and G. fumosus.