THE POLYPHYLETIC ORIGINS OF OPHIOSTOMATOID FUNGI

Cladistic analysis was performed on partial sequences from the nuclear-encoded small subunit ribosomal DNA. Taxa were sampled from Ceratocystis, Ophiostoma and Sphaeronaemella to determine the placement of the inferred monophyletic groups among non-fissitunicate perithecial ascomycetes. Eight equally most parsimonious cladograms resulted from the analysis. In a strict consensus of the eight cladograms, the taxa sampled from the three genera did not form a monophyletic group collectively. Ceratocystis and Sphaeronaemella formed a clade, which was a sister group to the taxa sampled from the Microascales. Ophiostoma was placed in a separate clade of the tree. These results support the convergent evolution of long-necked perithecia, scattered evanescent asci and galeate ascospores. Congruence of anamorph morphology, cycloheximide sensitivity, cell wall carbohydrate composition and centrum anatomy with the molecular data is discussed.