Rommelaarsia avovirens gen. et sp. nov. is proposed. This inoperculate discomycete is known only from two collections in Western Europe, fruiting in spring on dead stems of Equisetum arvensis. An a - liation with the family Hyaloscyphaceae is suggested by the presence of short hairs on the super cially gro- wing apothecium. The species is associated with an unusual, likewise unknown asexual state with large multiguttulate, holoblastic phragmoconidia formed in sporodochia. Phylogenetic analyses of the internal transcribed spacer (ITS) and large subunit (LSU) ribosomal DNA show that Rommelaarsia has an uncertain position within the Helotiales. Our analyses consistently show a close relationship to Cistella and Psilachnum, but there is no support for this placement. Bayesian analysis moderately supports the Cistella + Psilachnum+ Rommelaarsia clade, which hints at the placement of Rommelaarsia within Hyaloscyphaceae. This agrees with the morphological data.