The glittering-bellied emerald was widely called by the scientific name Chlorostilbon aureoventris, but in 2006 José Pacheco and Bret Whitney showed that lucidus is the correct specific epithet due to the principle of priority.

[3][4] The International Ornithological Committee (IOC) assigns three subspecies to the glittering-bellied emerald: the nominate C. l. lucidus, C. l. pucherani, and C. l. beflepschi.

The Clements taxonomy and BirdLife International's Handbook of the Birds of the World add C. l. igneous, whose population the IOC includes in the nominate.

It has a grayish white streak behind the eye and a whitish throat that darkens to pale brownish gray on the breast and belly.

[8] Subspecies C. l. pucherani of glittering-bellied emerald is found in eastern Brazil from Maranhão and Ceará all the way south to Paraná.

C. l. beflepschi is found from Rio Grande do Sul in southeastern Brazil through Uruguay into northeastern Argentina to Buenos Aires Province.

[8][11] The glittering-bellied emerald forages for nectar by trap-lining, visiting a circuit of a wide variety of flowering plants.

It makes a cup nest of fine plant fibers and bark strips held together by spiderweb, lined with softer material, and covered on the outside with lichen and other camouflage.

It typically places it on a thin branch in a small tree but nests have also been found attached to exposed roots about 1 m (3 ft) above the ground.