Sequestrate (truffle-like) fungi of Australia and New Zealand

Abstract

Sequestrate fungi are a polyphyletic, diverse group of macrofungi with truffle-like, underground (hypogeous) or emergent fruit bodies, which are well represented in Australia and New Zealand. The first species in the region were described in 1844, but sequestrate fungi have been poorly documented until recent times. Regional diversity of sequestrate fungi is high in comparison to other parts of the world: for ascomycetes and basidiomycetes 83 genera and 294 species are currently known in Australia and 32 genera and 58 species in New Zealand. Only an estimated 12–23% of species are known for Australia and 25–30% for New Zealand. On that basis, between 1278–2450 species may occur in Australia and 193–232 in New Zealand. Centres of diversity for some groups of sequestrate fungi occur in the region, e.g. Russulaceae (five known genera, 68 species) and Cortinariaceae (eight genera, 33 species). Some other groups are less diverse than in the northern hemisphere, e.g. sequestrate Boletaceae (seven genera, 25 species). More than 35% of Australian sequestrate genera and 95% of species are endemic; for New Zealand about 45% of sequestrate genera and 80% of species are endemic. Australia and New Zealand share similarities in sequestrate fungi at generic level (11% of total) but do not share many of the same species (4% of total). Knowledge of biogeographical distributions is limited by incomplete taxonomic knowledge and insufficient collections. Some Gondwanan, Australasian and widespread/cosmopolitan patterns are evident. Some exotic sequestrate fungi have been recently introduced and some fungi indigenous to the region occur world-wide as exotics with eucalypt plantings. Within Australia and New Zealand, there is evidence that characteristic suites of fungi co-occur in different climatic and vegetation types. Mycorrhizas of Australian and New Zealand taxa have a range of morphological and physiological attributes relating to their effect on plants and broader roles in ecosystem nutrient cycling and health. Spores of sequestrate fungi are dispersed by a range of fauna. There are tripartite inter-dependent interactions between mycorrhizal plants, sequestrate fungi and native mammals and birds that use the fungi as food. Major environmental influences affecting the distribution, diversity and abundance of sequestrate fungi include climate, topography, soil, vegetation and animals. Imposed upon such influences are a range of natural and human-induced disturbance factors which alter habitat heterogeneity, e.g. fire, fragmentation and replacement of native vegetation and exotic organisms. Rare and endangered sequestrate fungi are likely to occur in Australia and New Zealand, but for most taxa there is insufficient data to determine rarity or commonality. In the face of poor knowledge, assemblage-based and habitat-based approaches are the most appropriate for conservation and management of sequestrate fungi. Habitat heterogeneity may be important for the fungi at scales ranging from different climatic and vegetation types to local topographic-related variations.