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

Abstract

The genus Amylostereum currently includes four species, namely A. areolatum, A. chailletii, A. laevigatum and A. ferreum. Two of these species, A. areolatum and A. chailletii, are well known for their association with siricid woodwasps. Despite much interest in these fungus-woodwasp symbioses, the taxonomy and phylogeny of this genus received little attention in the past. The aim of this study was to investigate the phylogenetic relationship between the four species of Amylostereum. The placement of Amylostereum spp. among the Basidiomycetes was also investigated based on mt-SSU-rDNA sequence analyses. These data also clarify the taxonomic status of previously unidentified isolates. In this study, we have shown that A. areolatum is more distandy related to the three other species of Amylostereum, than they are to each other. Of the remaining three species, A. ferreum and A. laevigatum are more closely related to each other. One isolate that was collected from Sirex areolatus, and, therefore, expected to be A. chailletii, was more closely related to A. laevigatum and A. ferreum. As neither of the latter species have been implicated in associations with woodwasps, this finding warrants further investigation. Our data show that Amylostereum spp. group with neither Stereum nor Peniophora, as has been previously hypothesised, but rather with Echinodontium tinctorium. From this and other studies there was also an obvious relationship between Amylostereum/Echinodontium and Russula.

Key Words:

• mt-SSU-rDNA
• phylogeny
• symbiosis