The lichen was described as a new species in 2010 by Brazilian lichenologists Luciana da Silva Canêz and Marcello Marcelli.

The type specimen was collected in Rio Grande do Sul state, in the municipality of Vacaria.

Here it was found in an open field at an altitude of 860 m (2,820 ft), growing on the branch of a shrub, on the side of the Frade River.

The specific epithet honours Uruguayan lichenologist Héctor Osorio, who, according to the authors, "contributed much to the development of our knowledge of lichenology in the Brazilian State of Rio Grande do Sul".

[1] Punctelia osorioi is somewhat similar in morphology to Punctelia bolliana, but can be distinguished from that species by its denser rhizines on the margins of the thallus underside, and its smooth or scalloped lobe margins, which are never lacinate (irregularly and finely slashed) like in P. bolliana.