Relationships among Amylostereum species associated with siricid woodwaspsinferred from mitochondrial ribosomal DNA sequences

The genus Amylostereum currently includes four species, namely A. areolatum , A. chailletii, A. laevigatum and A. ferreum. Two of these species, A. are olatum and A. chailletii, are well known for their association with siricid woodwasps. Despite much interest in these fungus-woodwasp symbioses, the t axonomy and phylogeny of this genus received little attention in the past. The aim of this study was to investigate the phylogenetic relationship betw een the four species of Amylostereum. The placement of Amylostereum spp. am ong the Basidiomycetes was also investigated based on mt-SSU-rDNA sequence analyses. These data also clarify the taxonomic status of previously uniden tified isolates. In this study, we have shown that A. areolatum is more dis tantly related to the three other species of Amylostereum, than they are to each other: Of the remaining three species, A. ferreum and A. laevigatum a re more closely related to each other One isolate that was collected from S irex areolatus, and, therefore, expected to be A. chailletii, was more clos ely related to A. laevigatum and A. fer reum. As neither of the latter spec ies have been implicated in associations with woodwasps, this finding warra nts further investigation. Our data show that Amylostereum spp. group with neither Stereum nor Peniophora, as has been previously hypothesised, but ra ther with Echinodontium tinctorium. From this and other studies there was a lso an obvious relationship between Amylosterum/Echinodontium and Russula.