XVI International Botanical Congess

The genus Ceratocystis sensu sticto is composed of plant pathogens that are typically dispersed by insects. All Ceratocystis species have Chalara anamorphs with endoconidia from deep-seated phialides. Most Chalara species, however, have no known teleomorph. Our goal was to determine if all Chalara species have affinities with Ceratocystis. Phylogenetic analyses of 28S, 18S, and ITS sequences of the rDNA operon show a distinct division between plant pathogenic and non-pathogenic Chalara species. Six pathogenic Chalara species fall within the Ceratocystis clade, with Chalara elegans, C. populi, C. thielavioides and C. ovoidea forming an asexual lineage within Ceratocystis. The 16 non-pathogenic species form a monophyletic group well outside of the Ceratocystis clade, their relationship with other ascomycetes is not resolved.