The sequestrate relatives of Russula in Australia and New Zealand

The sequestrate ectomycorrhizal fungi of Australia and New Zealand are generally poorly documented, with much of the taxonomy historically and currently being done by researchers visiting from other countries. Unfortunately, the seasonality and variability in fruiting of fungi clouds the picture of overall diversity when most data are from visiting researchers. Knowledge of sequestrate fungi is further limited by their mostly hypogeous habit and by collectors mistaking some for aborted agarics, which are then discarded without closer examination. Until recently, most taxonomic literature on sequestrate fungi was from Europe and North America; consequently, many species have been placed in European genera. The specificity of association with native trees suggests that many Australasian ectomycorrhizal fungi are in fact endemic to the region. We review the taxonomic literature on the sequestrate macrofungi from Australia and New Zealand and summarise current research by both overseas and local scientists.; The Russulales are an important ectomycorrhizal order worldwide, with some 500 species and nine genera currently recognised. Only 12 species of sequestrate relatives of Russula were described from Australia and New Zealand prior to 1997. The region's high diversity of mycorrhizal hosts and large number of undescribed species of Russula suggested that the sequestrate relatives may also be more diverse than the literature suggests. We present the results of our examination of over 1100 collections of sequestrate relatives of Russula from Australia and New Zealand.; Full descriptions and illustrations of generic holotypes are presented. All sequestrate relatives of Russula (Macowanites, Cystangium, Martellia, Gymnomyces, Elasmomyces) from Australia and New Zealand were examined in order to revise the taxonomy of this difficult group. Several realignments are proposed, including (i) merging Martellia with Gymnomyces; (ii) merging Elasmomyces with Macowanites; (iii) transferring some species of Martellia into Gymnomyces; (iv) redistributing species of Elasmomyces among Macowanites and Cystangium, depending upon the structure of the peridiopellis; and (v) proposing a new genus (Rodwaya, typified by Gymnomyces seminudus). Keys to and descriptions of the Australasian genera and species of sequestrate Russulales are provided. Forty-three new species are proposed.