Phaeotremella frondosa
Phaeotremella frondosa (synonym "Tremella frondosa") is a species of fungus in the family Phaeotremellaceae producing brownish, frondose, gelatinous basidiocarps (fruit bodies). It is widespread in north temperate regions, and is parasitic on other species of fungi ("Stereum" spp.) that grow on dead attached and recently fallen branches of broadleaf trees. Taxonomy. "Tremella frondosa" was first published in 1822 by Swedish mycologist Elias Magnus Fries. The species was not clearly distinguished from "Tremella foliacea" until molecular research, based on cladistic analysis of DNA sequences, showed that the name "Tremella foliacea" covered several similar but distinct species. "Phaeotremella frondosa" is  the name adopted for the widespread species growing on broadleaf trees, whilst "Phaeotremella foliacea" is restricted to conifers. The epithet "frondosa" means "leafy", with reference to the shape of the fruit bodies. Description. Fruit bodies are gelatinous, pale to dark brown, up to 7 cm (3 in) across, and seaweed-like (with branched, undulating fronds). Microscopically, the hyphae are clamped and occur in a dense gelatinous matrix. Haustorial cells arise on the hyphae, producing filaments that attach to and penetrate the hyphae of the host. The basidia are tremelloid (globose to ellipsoid, with oblique to vertical septa), 13 to 18  by 12 to 16 μm, usually unstalked. The basidiospores are subglobose to broadly ellipsoid, smooth, 6.5 to 10.5 by 5 to 9 μm, and germinate by hyphal tube or by yeast cells. Similar species. "Phaeotremella foliacea" parasitizes "Stereum sanguinolentum" on conifers. "Phaeotremella fimbriata" is a European species parasitizing "Stereum rugosum" on broadleaf trees. Its fruitbodies are comparatively small and dark brown to black. "Phaeotremella eugeniae" is its temperate Asian counterpart. Habitat and distribution. "Phaeotremella frondosa" is a parasite of "Stereum" species, including "S. hirsutum" and "S. rugosum", growing on the host's hyphae in the wood rather than on the  host's fruit bodies. Following its hosts, fruit bodies of "P. frondosa" are typically found on dead, attached or recently fallen branches of broadleaf trees. The species is known from North America, Europe, and northern Asia.