Smithsoniun Contributions to Botany, №74, Washington, D.C. 1990. — 250 p.A world-level synopsis is presented for Xanthopurmeliu with full synonymies, typification of all taxa, species descriptions, and keys. The genus is characterized by the presence of usnic acid in the cortex, a positive lichenin test, oil bodies in the rhizines, saxicolous or temcolous habit, uniform small ellipsoid colorless spores, and bifusiform or rarely cylindrical conidia. The lower surface is rhizinate except in a few species and brown or black. Cilia are lacking. The 406 species occur primarily in southern Africa (212) and Australia (145).
Two new species are described: X. greytonensis Hale and X. kmuchstuniu Hale. Four new combinations are made: X. mutabilis (Taylor) Hale, X. perpleru (Stizenberger) Hale, X. sigillata (Brusse) Hale, and X. verecundu (Brusse) Hale. One new name is proposed X. neopropuguloides Hale.
