Famatinanthus, a new genus of Asteraceae (Mutisioideae, Onoserideae), is described and illustrated to accommodate one species from the Andes of Argentina, that was previously placed in Aphyllocladus, A. decussatus, as Famatinanthus decussatus comb. nov. The new genus is tentatively assigned to the tribe Onoserideae based on its shrubby habit, solitary radiate capitula, style rounded at the apex and dorsally papillose, and 2–3-seriate heteromorphic pappus. Famatinanthus is similar to Aphyllocladus but it is easily distinguished by the leafy, decussate branches with opposite leaves, multistoried T-trichomes, cream corollas, apiculate apical anther appendages, setuliferous achenes, terete stems, lack of secretory cavities, and pollen with a conspicuous mesoaperture and microechinate-rugulate exine. A key to the genera of the Onoserideae is presented. Affinities of the new genus with other genera of the tribes Gochnatieae, Hyalideae, and Stifftieae are also discussed.