The new genus Moquiniastrum, the result of recent phylogenetic analyses, is described. Although these analyses are based on cpDNA and nDNA, they also involve documentation of the distinctive morphological characters supporting this new genus. The recognition of Moquiniastrum is necessary to accurately reflect the relationships of the taxa found in the tribe Gochnatieae. Moquiniastrum includes twenty-one species that are usually gynodioecious and found mainly in Brazil but with some species elsewhere in South America. A description of Moquiniastrum, together with the corresponding new combinations, new lectotypifications of three names and one new neotypification is here provided.