Key features of Rosellinia (Xylariaceae, Ascomycetes) are uniperitheciate, subglobose, apically depressed, carbonaceous stromata with papillate ostioles nested in a subiculum and brown, unicellular ascospores, their length ranging from 10 µm to over 150 µm. Seven groups, each comprising morphologically homogeneous species, can be distinguished based on ascospore length: width ratio, synnematous or mononematous anamorph, subiculum extension, and stroma thickness. 142 species are accepted, including 37 new species, one new combination and one validated species name. A dichotomous key allows keying out Rosellinia-like genera; dichotomous keys to morphological groups and species within the genus are presented, along with a synoptic key, and all accepted taxa are illustrated on 72 photographic plates or by line drawings. Many taxa are represented by either few collections or only a single collection and only approximately twenty species by more than ten collections. Tables display the host range and the geographical distribution of the Rosellinia specimens examined. Excluded species are listed and selected literature on pathogenic species is reviewed. The reasons to accept Rosellinia, for the time being, as a heterogeneous genus, and not splitting it up, are critically discussed. This classical, taxonomic monograph addresses all mycologists interested in the morphology and taxonomy of xylariaceous fungi.weiterlesen