A revision of the genera Heterochaetella, Myxarium, Protodontia, and Stypella (Heterobasidiomycetes)

Nine species are described, illustrated, and referred to the genus Stypella . The genera Heterochaetella and Protodontia are proposed as synonyms of St ypella. The genus Myxarium is considered a synonym of Exidia. Stypella mira bilis is described as new. The new combinations Stypella crystalline, S. du bia, S. glaira, S. grilletii, S. subgelatinosa. S. sobhyalina, and Heteroch aete cystidiophora are proposed. The new species Stypella legonii is descri bed, based on the invalid Protodontia ellipsospora. Lectotypes are proposed for Hydnum enomalum, Heterochaete dubia, Sebacina fugacissima. Tremella gl acialis, and Sebacina podlachica. A number of new synonyms are put forward. Keys are provided to effused genera of the Exidiales and to species of Sty pella.