It is endemic to southern Brazil and only known from its type locality, Pico Marumbi, in the Serra do Mar in Morretes, Paraná state.

[4] The specific name ferruginus is a Latin noun and means "rust" or "reddish-brown".

The skin on top of the head and central part of the back body is smooth and without dermal co-ossification, whereas skin on the dorso-lateral surfaces of body, flanks, and dorsal surface of thighs is granular.

[2] Brachycephalus ferruginus inhabit the leaf litter in the Atlantic Rainforest.

[1][3] Its conservation status was last reviewed by the IUCN in 2008 where regarded as data deficient (insufficient information for rating it),[1] but an independent review in 2019 using IUCN's criteria recommended that B. ferruginus should be considered "least concern" (not threatened).