Phyllonorycter umukarus is a moth of the Gracillariidae family. It is found in south-western Rwanda. The habitat consists of open clearings in montane wet forests at an altitude of about 1,800 meters. The length of the forewings is 2.95–3.14 mm. The forewings are ochreous with golden shine and with shiny silver white markings. The hindwings are greyish beige with a long fringe of the same shading as the hindwings. Adults are on wing in early August. The larvae feed on Triumfetta cordifolia.