Biological Species of Armillaria in Japan.

Pairing tests with isolates of Armillaria in culture were used to identify species of Armillaria and their distribution throughout Japan. The existence of 10 intersterile groups of Armillaria was determined by pairing haploid single spore isolates obtained from 20 basidiocarps from a wide geographic distribution in Japan. Two to four haploid tester isolates from each intersterile group were then paired to biological and morphological species with haploid tester isolates from Europe and North America identified in previous studies. Japanese haploid tester isolates were then paired with 190 haploid or diploid isolates and compatibility reactions were used to identify these to species. Of the 10 intersterile groups identified in Japan, 7 were authenticated as A. gallica, A. nabsnona, A. ostoyae, A. cepistipes, A. mellea, A. sinapina, or A. tabescens. Three of the groups were not compatible with any of the tester species. The distribution and host relationships of the Japanese biological species are also discussed.