A new genus and species of Seuratiinae is described based on adults recovered from the Juan Fernández and Kermedec Petrels (Pterodroma externa and P. neglecta) from the Juan Fernández Islands of Chile (south Pacific). Navonia pterodromae n. gen., n. sp. is distinguished from the other genera and species in Seuratiinae by the combination of the following characters: (1) cordons arising from commissures of buccal lips originating a finely denticulate collarette divided into 2 lateral lobes, and detached from underlying cuticle; (2) inconspicuous simple to bicuspid deirids; (3) presence of area rugosa; and (4) presence of a large left spicule in the male. It is also distinguished from some genera and species in this subfamily by the presence of a lateral furrow. Seuratia shipleyi was also recorded from P. externa. These are the first records of helminths in these 2 hosts and the first records of Seuratiinae from Chile.