Fungi in the genus Geosmithia (Ascomycota: Hypocreales) are frequent associates of bark beetles and woodborers that colonize hardwood and coniferous trees. One species, Geosmithia morbida, is an economically damaging invasive species. The authors surveyed the Geosmithia species of California and Colorado, USA, to (i) provide baseline data on taxonomy of Geosmithia and beetle vector specificity across the western USA; (ii) investigate the subcortical beetle fauna for alternative vectors of the invasive G. morbida; and (iii) interpret the community composition of this region within the emerging global biogeography of Geosmithia. Geosmithia was detected in 87% of 126 beetle samples obtained from 39 plant species. Twenty-nine species of Geosmithia were distinguished, of which 13 may be new species. Bark beetles from hardwoods, Cupressus, and Sequoia appear to be regular vectors, with Geosmithia present in all beetle gallery systems examined. Other subcortical insects appear to vector Geosmithia at lower frequencies. Overall, most Geosmithia have a distinct level of vector specificity (mostly high, sometimes low) enabling their separation to generalists and specialists. Plant pathogenic Geosmithia morbida was not found in association with any other beetle besides Pityophthorus juglandis. However, four additional Geosmithia species were found in P. juglandis galleries. When integrated with recent data from other continents, a global pattern of Geosmithia distribution across continents, latitudes, and vectors is emerging: of the 29 Geosmithia species found in the western USA, 12 have not been reported outside of the USA. The most frequently encountered species with the widest global distribution also had the broadest range of beetle vectors. Several Geosmithia spp. with very narrow vector ranges in Europe exhibited the similar degree of specialization in the USA. Such strong canalization in association could reflect an ancient origin of each individual association, or a recent origin and a subsequent diversification in North America.

b School of Forest Resources and Conservation University of Florida PO Box 110410 Gainesville Florida 32611

c Department of Bioagricultural Sciences and Pest Management Colorado State University Plant Sciences Building 1177 Fort Collins Colorado 80523

Department of Microbiology and Plant Pathology Forestry and Agricultural Biotechnology Institute University of Pretoria 0002 Pretoria South Africa

e Department of Mycorrhizal Symbioses Institute of Botany Czech Academy of Sciences Zámek 1 252 43 Průhonice Czech Republic

f Chemical Ecology of Forest Insects United States Department of Agriculture Forest Service Pacific Southwest Research Station HDH001 Orchard Park Drive Davis California 95616

g Department of Plant Pathology University of California One Shields Avenue Davis California 95616

Institute of Microbiology Czech Academy of Sciences v v i Vídeňská 1083 142 20 Prague 4 Czech Republic

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