TL;DR: A new genus, Phoenicagrion, is here described to include L. flammeum and a new species, P. paulsoni, which does not belong in any of the described genera of New World CoenagRionidae.
Abstract: The placement of Leptagrion flammeum in Aeolagrion is confirmed to be incorrect; comparison with all other described genera of New World Coenagrionidae shows that this species does not belong in any of them. A new genus, Phoenicagrion (type species L. flammeum), is here described to include L. flammeum and a new species, P. paulsoni (holotype ♂: Peru, Loreto department, Rio Napo 50 km above Rio Amazonas, 3°12′S, 72°57′W, 22 iii 2004, in UMMZ). A generic characterization, diagnoses, illustrations and distribution maps are provided.