Reevaluation of the status of the bluestain fungus and bark beetle associate Ophiostoma minus

Thirty isolates of the morphological species Ophiostoma minus, obtained from Europe and North America, were compared using several criteria. These included sexual compatibility, linear growth rate, sensitivity to cycloheximide, perithecial dimensions and RAPD profiles. Within the species complex, three distinct mating populations were identified: sexually compatible heterothallic isolates originating from both Europe and North America, homothallic isolates occurring only in North America, and another group of heterothallic isolates corresponding to individuals previously identified as O. pseudotsugae from North America. Isolates of O. pseudotsugae were sexually incompatible with the heterothallic O. minus isolates. Differences in linear growth rate, perithecial size and RAPD banding patterns confirmed the differences among the three groups, and the combined evidence suggested these are three distinct species.