The monotypic genus Lorenzia E. G. Gonç. (Araceae — Spathicarpeae), with the type species Lorenzia umbrosa E. G. Gonç. is described and illustrated. It was collected in 2003 in Amapá state (Northern Brazil). Its novelty was predicted based on molecular phylogeny, but it was not until a cultivated specimen flowered in 2010 that was it possible to confirm its diagnostic morphological features. Evolutionary relationships (based on cpDNA marker matK) are discussed. Lorenzia is known only from a single remote locality in Serra do Navio, a moderately hilly portion of the Amazon, although it is possible that it also occurs in adjacent French Guiana.