Species of the genus Leptodactylus formerly referred to the genus Adenomera and now included in the Leptodactylus marmoratus species group are known to deposit eggs in foam nests in underground chambers. In this paper we detail the reproductive biology of a species of Leptodactylus (formerly Adenomera) from an open area in the Amazonian biome. We observed the breeding site, courtship behaviour, structure of underground chambers, and described the advertisement call and tadpole morphology. Leptodactylus aff hylaedactylus was found breeding in grasses (Brachiaria) and gardens in non-flooded areas, using underground chambers to lay its eggs. Underground chambers (n = 5) were simple constructions: a spherical chamber with no tunnel. We found tadpoles at different stages of development and obtained information about foam nest characteristics, time of hatching, size at metamorphosis, and fecundity. We tested in the laboratory the ability of tadpoles to generate foam independently of parents. The ability of the tadpoles to generate foam independently of the parents could represent a synapomorphy of the species of the Leptodactylus fuscus, pentadactylus and marmoratus species groups. The advertisement call of the species studied herein differs from other Amazonian Leptodactylus species and could represent a new species of this genus.