A new species of Metopiellus Raffray (Coleoptera: Staphylinidae: Pselaphinae) from the Atlantic Forest of Brazil, with keys to species of the genus and to the genera of Metopiasini

A new Brazilian species of Metopiellus Raffray from the Atlantic Forest biome is described. The species, Metopiellus emavieirae sp. nov., the seventh described for the genus so far, belongs to Metopiasini, a tribe suspected to be composed mainly of myrmecophiles. Nothing is known about the biology of the new species, which is morphologically similar to the recently described Metopiellus guanano Fiorentino, Tocora & Ramirez from Colombia. A key to the species of Metopiellus is provided, as well as two keys to genera of Metopiasini, one dichotomous and one multi-entry, online-based.