It is very tiny and was one of seven new species described by LF Ribeiro and a team of scientists from the Mater Natura - Instituto de Estudos Ambientais in Brazil.

Like all species in its genus, it is found in a very small strip of Atlantic Forest in the southeastern coast of the country, and has a vibrant colour pattern.

[1] The speciation seen in this genus is thought to be a byproduct of the rift between the valley versus mountain terrain and its particular microclimates, to which they are adapted.

It is distinguished from other cogenerate species by having a robust body, bufoniform, with an adult length between 9.4 and 12.9 millimetres (0.37 and 0.51 in); a rough dorsum, and its general coloration being predominantly dark-green to brown.

[1] Brachycephalus olivaceus is known only from two localities, which are the base of the Serra Queimada and Castelo dos Bugres, a notable rock formation in the northeastern State of Santa Catarina.