James M. Trappe

Diversity and habitat relationships of hypogeous fungi. II. Factors influencing the occurrence and number of taxa

Fruit-bodies of hypogeous fungi were sampled over two seasons across 136 forested study sites representing a stratified sample of the climatic, geological and topographic features of far south-eastern mainland Australia. Two hundred and nine species, over three-quarters being undescribed, were recorded. Statistical models based on various environmental attributes measured for each site were developed for the occurrence of several common taxa. At a landscape scale, climatic factors such as mean minimum temperature of the coldest month and annual mean moisture index were important explanatory variables for most taxa examined, but the type of response varied. More locally, topographic position, soil fertility, time since last fire and micro-habitat structures such as the leaf litter layer and number of large fallen trees also influenced the distribution of taxa in different ways. A model was then developed for the number of fungal species occurring at each site. Important explanatory variables were type of substrate, topography and diversity of potential host eucalypt species. The utility of each model constructed needs evaluation by further sampling of hypogeous fungi. Possible implications of our findings for forest management are discussed. Further analyses of our existing data are also identified.

Mycophagy by the swamp wallaby (Wallabia bicolor)

Microscopic analysis of the scats of swamp wallabies (Wallabia bicolor), collected from a variety of forested sites in south-eastern mainland Australia, indicates that the species consumes a diversity of species of hypogeous (underground-fruiting) fungi. The mycophagous (fungus-feeding) dietary behaviour seemingly extends to habitats recently burned by fire, implying that W. bicolor may be critical in dispersing fungal spores and perhaps in re-establishing mycorrhizal associations of these fungi with forest trees and shrubs. Such an interrelationship has been previously demonstrated only for more heavily mycophagous species of ground-dwelling mammal.

Description and distribution of Tuber incognitum sp. nov. and Tuber anniae in the Transmexican Volcanic Belt

The genus Tuber is a lineage of diverse ectomycorrhizal, hypogeous, sequestrate ascomycete fungi that are native to temperate forests in the Northern Hemisphere. Recently, many new species of Tuber have been described in North America and Asia, based on morphological characteristics and molecular data. Here we describe and illustrate a new species, Tuberincognitum, based upon phylogenetic analysis and morphological description. We also present a new record for Tuberanniae in México. These two Tuber species are distributed in the Transmexican Volcanic Belt in the states of México, Michoacán, Guanajuato, Querétaro and Tlaxcala at altitudes between 2,000 and 3,200 meters. These species are associated with Pinus (T.anniae) and Quercus forests (T.incognitum).