Phylogeny and taxonomy of the Ophiostoma piceae complex and the Dutch elm disease fungi

The Ophiostoma piceae complex forms a monophyletic group of insect-disperse d pyrenomycetes with synnemata (Pesotum) and micronematous (Sporothrix) syn anamorphs. Other species of Ophiostoma outside of the O. piceae complex tha t form synnemata lack the Sporothrix state. The nine recognized species wit hin the O. piceae complex are delimited by synnema morphology, growth rate at 32 C, mating reactions and sequences of the internal transcribed spacer (ITS) legion of the rDNA operon. Phylogenetic analysis of the ITS region su ggests two major clades in the complex, one that causes bluestain in primar ily coniferous hosts and the other on primarily hardwood hosts. III the con iferous group are O. piceae, O. canum, O. floccosum and the recently descri bed O. setosum (anamorph Pesotum cupulatum sp. nov.). In the hardwood group are O. querci, O. catonianum, and the Dutch elm disease fungi: O. ulmi, O. novo-ulmi and O. himal-ulmi. Restriction fragment length polymorphisms of the ITS region are shown to be a convenient diagnostic tool for delimiting these species.