BackgroundPhilodendron is the second largest genus of Araceae, being highly diverse in the Atlantic Forest biome, with nearly one third of the Brazilian species occurring in Southern Brazil, particularly in Rio de Janeiro state. During a local inventory in Silva Jardim municipality, we found a peculiar population of Philodendron growing in lowland rainforest.ResultsAfter morphological analysis and comparisons with similar species, the population proved to be a new undescribed species of subgenus Philodendron section Macrobelium.ConclusionsThe new species, named Philodendron luisae, is here described, illustrated and compared to morphologically close species.Electronic supplementary materialThe online version of this article (doi:10.1186/s40529-015-0082-x) contains supplementary material, which is available to authorized users.