A new species of the coenagrionid damselfly genus Papuagrion is described from the lowlands of the Purari River basin in Gulf Province, Papua New Guinea. Papuagrion forceps sp. nov. is a large (abdomen + appendages 46.5–47.2 mm) slender species with a predominantly black and brown abdomen. The male is unique in the genus in having superior appendages that are minute in comparison to the inferior appendages, with lower branches that are not visible in profile. The new species is currently known only from the type locality, where a male and a female were perched among low foliage in a remnant patch of lowland rainforest.