[2] The type series consists of two adult males measuring 17.6 and 18.7 mm (0.69 and 0.74 in) in snout–vent length.

The body is robust, with broad head, truncate shout, relatively short legs, and small eyes.

The ventral surfaces are finely mottled in dark and light brown.

[2] The male advertisement call has been described as "a series of rapid, high-pitched peeps".

[2] Barygenys parvula inhabits primary tropical rainforest at about 1,500 m (4,900 ft) above sea level.