Disentangling the species diversity of Inocybe sect. Petiginosae (Inocybaceae) in Europe and North America

Abstract A multigene phylogenetic assessment of European and North American species in Inocybe sect. Petiginosae based on ITS, LSU and RPB2 rDNA sequence data was undertaken to enable a systematic revision. Specimens collected in northern boreal to arctic-alpine ecosystems were shown to include an unexpected high genetic diversity and revealed several new species. In total, 22 clades were identified as independent species occurring in Europe and North America. Of these clades, 7 represent already described species, namely I. duploparvula , I. egenula , I. glareophila , I. jacobi , I. nigrodisca , I. petiginosa and I. subexilis . The other 15 are described as new species, viz. I. abscondita , I. algida , I. baeocarpa , I. boreonematoloma , I. dryadophila , I. ignota , I. inconspicua , I. melleicolor , I. parilis , I. patellaris , I. paulula , I. peregenula , I. perjacobi , I. pseudotsugae and I. tepidula . In addition, two supported clades including environmental ITS data from the arctic-alpine zones were recovered, suggesting there are more undescribed species to be identified. Lecto-typification of, and an epitype for, I. petiginosa is selected. Inocybe rufoalba and I. fulvella are proposed to be synonyms of I. petiginosa , and I. nematoloma a synonym of I. subexilis . Specimens previously determined to I. nematoloma originating from moist coniferous forests in the northern boreal zone is here described as I. boreonematoloma . We confirm that both I. subexilis and I. nigrodisca occur in Europe. Emended descriptions of described species are provided in addition to the descriptions of new species. A key to the species is provided based on morphology, ecology, host preferences and geographic distribution.