The genus Carminatia, which occurs from the southwestern United States to Central America, comprises annuals with cordate to broadly ovate leaves, paniculiform capitulescences that are often spike-like or narrowly raceme-like and with mostly fasciculate capitula, and a pappus of plumose bristles. We used nuclear ribosomal DNA (ITS and ETS) and the plastid psbA-trnH spacer DNA sequences to estimate phylogenetic relationships among the species of Carminatia, which have not been fully investigated using molecular data to date. All of our analyses supported the monophyly of the genus and most of them supported Brickelliastrum as sister to Carminatia. The analyses also supported the recognition of a new species, C. balsana, which is confined to the Balsas Basin in Mexico. The new species is more similar to C. recondita, but has shorter capitula, corollas, and cypselae, and the capitula are oriented to more than one side of the capitulescence. An updated taxonomic revision of the genus, including morphological descriptions, a key to the species, distribution maps, and images is provided.