Armillaria possesses several intriguing characteristics that have inspired wide interest in understanding phylogenetic relationships within and among species of this genus. Nuclear ribosomal DNA sequence-based analyses of Armillaria provide only limited information for phylogenetic studies among widely divergent taxa. More recent studies have shown that translation elongation factor 1-α (tef1) sequences are highly informative for phylogenetic analysis of Armillaria species within diverse global regions. This study used Neighbor-net and coalescence-based Bayesian analyses to examine phylogenetic relationships of newly determined and existing tef1 sequences derived from diverse Armillaria species from across the Northern Hemisphere, with Southern Hemisphere Armillaria species included for reference. Based on the Bayesian analysis of tef1 sequences, Armillaria species from the Northern Hemisphere are generally contained within the following four superclades, which are named according to the specific epithet of the most frequently cited species within the superclade: (i) Socialis/Tabescens (exannulate) superclade including Eurasian A. ectypa, North American A. socialis (A. tabescens), and Eurasian A. socialis (A. tabescens) clades; (ii) Mellea superclade including undescribed annulate North American Armillaria sp. (Mexico) and four separate clades of A. mellea (Europe and Iran, eastern Asia, and two groups from North America); (iii) Gallica superclade including Armillaria Nag E (Japan), multiple clades of A. gallica (Asia and Europe), A. calvescens (eastern North America), A. cepistipes (North America), A. altimontana (western USA), A. nabsnona (North America and Japan), and at least two A. gallica clades (North America); and (iv) Solidipes/Ostoyae superclade including two A. solidipes/ostoyae clades (North America), A. gemina (eastern USA), A. solidipes/ostoyae (Eurasia), A. cepistipes (Europe and Japan), A. sinapina (North America and Japan), and A. borealis (Eurasia) clade 2. Of note is that A. borealis (Eurasia) clade 1 appears basal to the Solidipes/Ostoyae and Gallica superclades. The Neighbor-net analysis showed similar phylogenetic relationships. This study further demonstrates the utility of tef1 for global phylogenetic studies of Armillaria species and provides critical insights into multiple taxonomic issues that warrant further study.

b Department of Bioagricultural Sciences and Pest Management Colorado State University 307 University Avenue Ft Collins Colorado 80523

c College of Bioresource Sciences Nihon University 1866 Kameino Fujisawa Kanagawa 252 0880 Japan

e Departamento de Agronomía División de Ciencias de la Vida Campus Irapuato Salamanca Universidad de Guanajuato C P 36824 Apdo Postal 311 Irapuato Guanajuato México

f Isontammentie 90 FI 02400 Kirkkonummi Finland

g Faculty of Forestry University of Belgrade Kneza Viseslava 1 11030 Belgrade Serbia

h Neiker Tecnalia Production and Plant Protection Granja Modelo de Arkaute 46 Post Vitoria Gasteiz 01080 Spain

i Colegio de Postgraduados Campus Montecillo Instituto de Fitosanidad Fitopatología Texcoco 56230 México

j Norwegian Institute of Bioeconomy Research Pb 115 NO 1431 Ås Norway

k UMass Extension Center for Agriculture Food and the Environment University of Massachusetts Amherst Massachusetts 01002

Kansai Research Center Forestry and Forest Products Research Institute 68 Nagai Kyutaro Momoyama Fushimi Kyoto 612 0855 Japan

l Department of Forest Pathology Poznan University of Life Sciences Wojska Polskiego 71c 60 625 Poznań Poland

m Sveriges Lantbruksuniversitet Swedish University of Agricultural Sciences Southern Swedish Forest Research Centre 230 53 Alnarp Sweden

o Department of Infectious Diseases Faculty of Medicine University of Miyazaki Miyazaki 889 1692 Japan and Forestry and Forest Products Research Institute Matsunosato 1 Tsukuba Ibaraki 305 8687 Japan

p Facultad de Ciencias Forestales Universidad Autónoma de Nuevo León Linares Nuevo León Mexico

q NAGREF Institute of Mediterranean Forest Ecosystems Terma Alkmanos 11528 Athens B O 14180 Greece

r Swiss Federal Research Institute WSL Zuercherstrasse 111 CH 8903 Birmensdorf Switzerland

s Canadian Forest Service Natural Resources Canada PO Box 10380 Stn Sainte Foy Quebec City Quebec G1V 4C7 Canada

t Agriculture and Agri Food Canada KW Neatby Bldg Ottawa Ontario K1A 0C6 Canada

u Department of Plant Protection Faculty of Agricultural Science and Engineering College of Agriculture and Natural Resources University of Tehran Karaj 31587 77871 Iran

United States Department of Agriculture Forest Service Rocky Mountain Research Station 1221 South Main Street Moscow Idaho 83843

United States Department of Agriculture Forest Service Rocky Mountain Research Station 735 North 500 East Provo Utah 84606

v Moravian Museum Department of Botany Zelny trh 6 659 37 Brno Czech Republic

w Faculty of Forestry and Wood Technology Mendel University in Brno Zemědělská 3 CZ 613 00 Brno Czech Republic

x Department of Plant and Soil Sciences Institute of Biological and Environmental Sciences University of Aberdeen Aberdeen AB24 2TZ Scotland UK

y Department of Forestry Environment and Systems Kookmin University Seoul 02707 Republic of Korea

Mycologia. 2017;109(2):359. doi: 10.1080/00275514.2017.1330016. PubMed

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