Summary:
Phaeotremella foliacea produces a large brownish convoluted mass of wavy or leaf-like, brown, gelatinous folds. It is parasitic on Stereum sanguinolentum and apparently limited to conifer wood. Tremella frondosa and Tremella foliacea have been considered synonyms by some authors and at least 12 different publication have discussed the question, sometimes using different concepts for Tremella frondosa. Original type material did not survive, and Spirin(1) selected lectotypes and epitypes based on clues in the early descriptions, prior discussions in the literature, and molecular-backed knowledge of current species. They assembled evidence to support separating Phaeotremella foliacea (growing on conifers associated with Stereum sanguinolentum) from Phaeotremella frondosa (growing on hardwoods associated with other Stereum species), and from four other species of Phaeotremella growing outside North America. In addition to the host differences, the spores of P. frondosa average larger, but the variation range in both species is wide, so that "basidiospore size only is not a stable character to distinguish these two species". The description of Spirin(1) is sparse, so that earlier North American descriptions, probably encompassing Tremella frondosa as well as T. foliacea, are left to provide some extra detail. The current name of Tremella foliacea Pers. in the online Species Fungorum, accessed February 26, 2018 is Phaeotremella foliacea (Pers.) Wedin, J.C. Zamora & Millanes, but MycoBank, accessed the same day, gave the current name as Phaeotremella pseudofoliacea Rea. On the other hand Spirin(1) synonymize P. pseudofoliacea with P. frondosa.

Microscopic:
spores (5.2)5.3-9.1(10.2) x (4.6)4.7-8.5(9.5) microns, broadly elliptic to nearly round, colorless to brownish; basidia 4-spored, 12-18 x 10-14 microns, "ovoid to subglobose", "slightly thick-walled", with colorless or brownish content; swollen cells "often present on basal lobes, broadly ellipsoid to globose, slightly to very thick-walled", up to 25 microns in diam, producing conidial cells, 4-10 x 3-7 microns, elliptic or nearly round; clamp connections present, (Spirin), spores 8-9(13) x 7-9 microns, ovate to round, germinating by repetition; hymenial conidia lacking; probasidia 12-16 x 10-14 microns, broadly elliptic to nearly spherical, becoming cruciate-septate, (Martin), spores 7-9(13) x 6-9 microns, round to broadly elliptic, smooth, spore deposit white to yellowish, (Arora), spores form on outer surfaces (Lincoff)

Notes:
In the Pacific Northwest, Tremella foliacea has often been reported growing on conifers - these would be Phaeotremella foliacea in the newer restricted sense of Spirin(1). There are collections from conifer wood at the University of British Columbia from BC and WA and a collection at Oregon State University from conifer branches in OR.

Synonyms and Alternate Names:
Polyporus nitidus Fr.
Poria eupora (P. Karst.) Cooke