Serra do Mar bristle tyrant

The Serra do Mar bristle tyrant (Pogonotriccus difficilis) is a small species of bird in the tyrant flycatcher family Tyrannidae. It was formerly placed in the genus Phylloscartes and known in English as the Serra do Mar tyrannulet. It is endemic to humid montane forest in the Serra do Mar in south-eastern Brazil. More likely confused with the short-tailed and pale-eyed hangnest tody-tyrant, its bright olive-green upperparts contrast strongly with the grey underparts. It is generally uncommon and threatened by habitat loss.

Taxonomy
The Serra do Mar bristle tyrant was formally described in 1907 by the German-Brazilian naturalists Hermann von Ihering and his son Rodolpho von Ihering. They introduced a new genus, Guracava and coined the binomial name Guracava difficilis.The type locality was specified as Itatiaia in the Brazialian state of Rio de Janeiro. The specific epithet is Latin meaning "difficult". The Serra do Mar bristle tyrant was formerly placed with the tyrannulets in the genus Phylloscartes and known in English by the name Serra do Mar tyrannulet. A comprehensive molecular phylogenetic study of the suboscines by Mike Harvey and collaborators, published in 2020, found that the "Serra do Mar bristle tyrannulet" was embedded in a clade containing the bristle tyrants in the genus Pogonotriccus. Based on this result, the "Serra do Mar tyrannulet" was moved to Pogonotriccus and at the same time the English name was changed from Serra do Mar tyrannulet to Serra do Mar bristle tyrant. The species is monotypic: no subspecies are recognised.