Identification of group I introns within the SSU rDNA gene in species of Ceratocystiopsis and related taxa

► Group I introns were found in the nuclear rDNA in species of Ophiostoma sensu lato. ► The SSU rDNA phylogeny does support the status of Ceratocystiopsis and Grosmannia. ► The S943 intron within Ceratocystiopsis is probably transferred vertically. ► Frequent loss explains the absence of S943 within some species of Ceratocystiopsis.