A new species of Phyllarthron DC. (Bignoniaceae) is described from Northern Madagascar: Phyllarthron longipedunculatum Callm. & Phillipson, sp. nov. The new species is endemic to low elevation tropical evergreen forests and is known from the North of the Masoala peninsula and around the foothills of the Kalobinono and Tsaratanana massifs. The new species differs from all the other species of the genus by its petiolate articulate phyllodes reduced to a single article and the cauliflorous inflorescences gathered on a contracted raceme at the apex of a long peduncle. Line drawings are provided, along with a discussion of its morphological affinities and a preliminary risk of extinction assessment.