Thermopolynoe branchiata, a new genus and species of branchiate polynoid polychaete from the Lau Back-Arc and the North Fiji Basins, South Pacific Ocean, is described. The new species belongs to the subfamily Lepidonotopodinae in having well-developed notopodial bracts. It, however, differs from the other species of the subfamily in having arborescent branchiae. Thermiphione fijiensis, a new species of the subfamily Iphioninae from the North Fiji Basin, differs from T. tufari by the first occurrence of hooked neurosetae: segment 3 instead of segment 4 of the latter.