Quasitagalis afonsoi, a new genus and a new species of Saicinae (Hemiptera, Reduviidae) inhabiting a cave in Brazil, with an updated key to the genera of Saicinae of the New World.

Quasitagalis afonsoi gen. et sp. nov. of Saicinae (Hemiptera, Reduviidae) is described based on a male and three female specimens collected in a cave in the State of Tocantins, Brazil. Additionally, some characteristics from two nymphs of different instars of the same species are also recorded. An updated key to the New World genera of Saicinae is provided.