Multigene phylogenies of Ophiostoma clavigerum and closely related species from bark beetle-attacked Pinus in North America.

Leptographium pyrinum, Leptographium terebrantis, Ophiostoma aureum, Ophiostoma clavigerum, and Ophiostoma robustum are very similar in morphology, host trees choice, and the way they are disseminated by bark beetles. Their phylogenetic relationships were clarified using rDNA and protein coding genes including actin, beta-tubulin, and translation elongation factor-1alpha. Protein coding gene trees showed better resolution than the rDNA tree, which generated three clades: O. clavigerum, L. terebrantis/L. pyrinum, and O. robustum/O. aureum. A combined gene phylogenetic tree, which was supported by high bootstrap values, showed that O. aureum, L. pyrinum, O. robustum, and O. clavigerum each formed distinct clades while L. terebrantis was paraphyletic to O. clavigerum. The higher variability of the protein coding genes and the congruity in their phylogenetic results suggested that these genes may be better markers for identifying closely related species. These gene trees have also facilitated the description of the evolutionary relationships among these species.