Phylogeny of asexual fungi associated with bark and ambrosia beetles

Asexual ascomycetes were isolated from Polygraphus polygraphus or Hylurgops palliatus (Coleoptera: Scolytidae) (NISK-93-208/44 and NISK-94-166/39, res pectively) in a Norway spruce (Picea abies) forest. Although the two fungal isolates are distinct in appearance and display specificity to different h osts, the isolates are genetically identical in the nuclear encoded small s ubunit, large subunit, and internal transcribed spacer rRNA gene regions th at we sequenced. Phylogenetic analyses and observations based on DNA placed the Norwegian isolates in an Ophiostoma clade. Within the clade the isolat es occurred in a subclade with O. ulmi and O. piliferum and several Ambrosi ella species (A. macrocarpa, A. tingens, and A. ips). A second subclade con tained additional species of Ophiostoma and Ambrosiella. The beetle vectors of the fungi have different flight times and host tree usage, suggesting t hat their behavior helps to isolate the fungi in time and space.