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Mesoamerica is famous for its complex biota assembled from diverse sources. The recent discovery of a highly distinct freshwater catfish, Lacantunia enigmatica (Lacantuniidae), in Chiapas, México, added an unresolved taxon to this biogeographic puzzle. Morphology has not resolved the relationships of Lacantunia among the >3000 species of Siluriformes. We added Lacantunia to an expanding phylogenetic study of family-level taxa of living catfishes using >3.6 kilobases of nuclear DNA. We find that Lacantunia is derived from within a multi–family clade of African freshwater catfishes. Without living or fossil intermediates marking a wider lacantuniid distribution, this is an extraordinary case of biogeographic disjunction. Continental clades distributed in the New and Old World tropics are often explained by vicariance of Gondwanan ancestors of deep Mesozoic age. However, our fossil-calibrated, relaxed-clock …