The chestnut-bellied euphonia (Euphonia pectoralis) is a species of bird in the Fringillidae family. It was formerly placed with the related Thraupidae. It is found in Argentina, Brazil, and Paraguay. Its natural habitats are subtropical or tropical moist lowland forests and subtropical or tropical moist montane forests.
The black-throated euphonia (“Euphonia vittata”) is now thought to be a hybrid between the chestnut-bellied euphonia and the orange-bellied euphonia. source