Artificially colored ascospores of the saprobic microfungus Aliquandostipite khaoyaiensis(Loculoascomycetes, Ascomycota). The ascospores are hyaline, ~60 µm long, and surrounded by an appressed sheath that detaches when it comes in contact with water. The fungus is thus far known only from the type locality in a tropical rain forest in Thailand. Fruitbodies are ~0.25 mm across, light to dark yellow in color, and formed on decaying wood on the ground. Partly because of their small size, saprobic microfungi are poorly known. Surveys, especially in the tropics, regularly yield high proportions of new species, of which many are difficult to place in the existing taxonomic system, even at the ordinal level.
Of the estimated 1.5 million species of fungi, only 5% are presently known
to science, but even this small fraction includes a bewildering variety of forms
and ecological types. Recent Tree of Life studies have begun to clarify the
complex relationships observed in most fungal groups, and new discoveries aid
in this effort. A new species of Marchandiomyces, discovered recently
in Australia by Guy Marson and described in this issue, is helping to shed light
on the remarkable nutritional diversity of the basidiomycete order Corticiales,
which includes saprophytes, plant and fungal pathogens, lichen-forming fungi,
and now leaf-inhabiting (foliicolous) species. The new species produces small,
coral bulbils (inset) on the dead leaves of screw pines (Pandanus oblatus).
These bulbils, which probably function as resting or dispersal structures, resemble
apothecia of the ascomycete genus Orbilia, which Marson was collecting
at the time. This first Marchandiomyces species described from Australia
is unusual not only in appearance, but also in ecology. A new molecular phylogeny
of the Corticiales, including M. marsonii, makes clear that Marchandiomyces
species contribute significantly to the nutritional diversity of the order.