Tremella iduensis

Tremella iduensis is a species of fungus in the family Tremellaceae. It produces yellow, cornute-frondose, gelatinous basidiocarps (fruit bodies) and is parasitic on other fungi, probably species of Hypoxylon on dead attached and recently fallen branches of broad-leaved trees. It has been recorded from Japan and China. Tremella flava, described from Taiwan, may be a synonym.

Taxonomy
Tremella iduensis was first published in 1939 by Japanese mycologist Yosio Kobayasi.

Description
Fruit bodies are gelatinous, bright yellow, up to 2.5 cm (1 in) across, and branched, with cornute (horn-like) fronds. Microscopically, the basidia are tremelloid (ellipsoid, with oblique to vertical septa), 4-celled, 17 to 18 by 12 to 13 μm. The basidiospores are ovoid to ellipsoid, smooth, 8.5 to 9.5 by 7.5 to 8.5 μm.

Similar species
Tremella flava was described from Taiwan as "resembling T. iduensis" but differing in the size of its basidiospores (7 to 9 by 5 to 6.5 μm) and basidia. It has been suggested it may be a later synonym of T. iduensis. Other yellow Tremella species are lobed or foliaceous and lack horn-like fronds.

Habitat and distribution
Tremella iduensis is a parasite on lignicolous fungi, probably species of Hypoxylon. It was originally described from Castanopsis sieboldii and is found on dead, attached or recently fallen branches of broad-leaved trees.

The species is currently known from Japan and China.