This mould-like fungus is parasitic on the fruiting bodies of several fungus species, mainly boletes. The Brown Bolete almost always becomes infected. The only other affected species I have noted in Woodlands Historic Park is Phylloporus clelandii which is only occasionally attacked. The susceptibility of Phylloporus to H. chrysospermus (under the synonym Sepedonium chrysospermus) has been previously noted by Watling (1991, page 384).
Hypomyces chrysospermus has three stages of growth - at first a layer of white grows to cover the whole of the host, then a thick yellow powder appears as shown in the photo above, and finally it becomes reddish-brown and pimpled. In the first two stages asexual spores are being produced, and in the third stage sexual spores.
Another species (presumably) of Hypomyces has been seen in the park infecting the White-rimmed Polypore.