Endemic and distinctive, medium-sized hummingbird found in the foothills of the Sierra Madre del Sur in Oaxaca. Favors humid evergreen forests and shade-coffee plantations. Mainly feeds at low to middle levels, darting quickly among flowers and flashing open its mostly white tail. Both sexes have a bright rusty panel in the wings, which appears as a blur when hovering. Male is brilliant green overall with blue cap. Female is pale gray below and has less white in the tail.