Dolichomitus Smith, 1877 is a genus of Darwin wasps characterised by their large bodies and long ovipositors, that includes more than 75 species worldwide, 20 of which occur in the Neotropical Region. Due to recent efforts, the number of species of this genus continues to increase in South America. A new iridescent species of Pimplinae, Dolichomitus meii sp. nov., is described and illustrated. It was discovered from the biological station of Yanayacu located in the north-eastern slopes of the tropical Andes. It may be separated from all other species of Dolichomitus Smith by the striking colour pattern and apically strongly decurved ovipositor.