I describe a new frog of the microhylid genus Hylophorbus from the north-coast mountain ranges of Papua New Guinea that is unique in its small size, continuous black lateral band bordered below by a white line and then a field of whitish gray, and other morphometric and color-pattern features that distinguish it from its two most similar congeners, each also possessing a black lateral band. The new species is one of the two smallest species in the genus. It is currently known only from two of the easternmost north-coast mountain ranges, although it seems likely to occur in nearby mountain ranges to the west, a distributional pattern that is common among endemic amphibians from this region.