We describe a new species of large green treefrog from southern Papua Province, Indonesia. Litoria lubisi sp. nov. is placed in the L. infrafrenata Group based on its size, colouration and configuration of hand webbing, but differs from other members of this group in aspects of body size and proportions, extent of hand webbing, colouration and male advertisement call. Litoria lubisi sp. nov. occurs in close proximity to two other species in the L. infrafrenata Group, emphasising an until-recently overlooked pattern that multiple species of large, arboreal Litoria have overlapping distributions across much of the lowlands of southern New Guinea.