Three microcyclic rust species were collected during surveys of the perennial asteraceous vine Mikania micrantha (Eupatorieae: Asteraceae) throughout its native range in the Neotropics but were absent in its invasive range in Asia. The commonest species, Puccinia spegazzinii with brown telioid telia, occurred wherever M. micrantha was found in South and Central America including the Caribbean island of Trinidad. Dietelia portoricensis, with occasional vestigial spermogonia and grayish-white to pale yellow columnar aecioid telia, was collected only in Costa Rica; while D. mesoamericana sp. nov., apparently restricted to Mesoamerica, can be distinguished by its abundant, yellowish-orange, fertile spermogonia, yellow to pale brown telial columns, larger teliospores, and 4-spored rather than 2-spored metabasidia. The fact that all three species share a fundamentally similar symptomatology suggests a common origin.