In 1999, Andreas Bresinsky and colleagues studied the genus
Paxillus, which appeared to have a centre of diversity in the Southern Hemisphere as a number of species had been described from Australia, New Zealand, Chile and Argentina in southern South America.
Genetic analysis revealed that members of what had been broadly construed as
Paxillus fell into three distinct
clades. The Southern Hemisphere species were found to be in a lineage that is most closely related to the
brown rot genus
Serpula. Supporting this is the finding that the compound 2,4,5-trihydroxyphenylglyoxylic acid has been isolated from members of both
Austropaxillus and
Serpula. Hence they moved these species into the new genus
Austropaxillus. Later analysis revealed a relationship to
Gymnopaxillus, a small genus of
truffle-like fungi known from south-eastern Australia, Argentina, and Chile.
Austropaxillus and
Gymnopaxillus, both
mycorrhizal genera, form a
monophyletic clade that is
sister to the
saprotrophic genus
Serpula. Using
molecular clock analysis, the split between
Austropaxillus and
Serpula has been estimated to have occurred about 34.9
mya, roughly coinciding with the separation of South America and Australia from Antarctica. The prefix
Austro is derived from the
Latin word
auster "south". The
type species is
Austropaxillus statuum from South America. ==Description==