A phylogenetic revision of the Neotropical riodinid genus Calydna Doubleday and relatives is presented. A phylogenetic analysis for all twenty species of Calydna using thirty-eight characters of adult morphology generated four most parsimonious cladograms. Calydna is characterised to contain eighteen species, divided here into three monophyletic species groups with the relationship caieta group + (thersander group + hiria group). A new genus Echydna Hall gen. n. is described for the most basal clade, containing chaseba Hewitson and punctata C. & R. Felder, which are transferred from Calydna (combs. n.). The taxonomy, morphology, biogeography and biology of both genera are discussed, locality data is listed and mapped, and the adults and male and female genitalia are illustrated for all species. Concealed male abdominal androconial scales, which phylogenetically unite the thersander and hiria groups, are reported for the first time outside of the tribes Symmachiini and Nymphidiini. Two new species are described, Calydna jeannea sp. n. and Calydna nicolayi sp. n., and the replacement name fissilisima is provided for the unavailable name fissilis Stichel; maculosa Bates is transferred from Calydna to Callistium Stichel (comb. n.).