Isocarpha has five species distributed in North America, Mexico, the Caribbean, Central America, and South America. In Brazil, three species occur in the Caatinga and Cerrado phytogeographic domains. During the taxonomic treatment of the species from the Eupatorieae tribe, a new species of Isocarpha was discovered for the Northeast of Brazil, in the Caatinga domain. Isocarpha spathulata is distinguished from other species of the genus by an ovate to widely-ovate or ovate-rhombic leaf blade, a sessile to subsessile capitulum that is one to two mm long, a spathulate palea with a rounded apex, 36–40 flowers, a persistent stylopodium, and an annuliform or inconspicuous carpopodium. Morphological description, illustration, distribution map, conservation status, and an identification key for Isocarpha taxa are presented herein.