Phyllonorycter caudasimplex is a moth of the Gracillariidae family. It is known from Nigeria. The length of the forewings is 3.2 mm. The forewings are ochreous brown with white markings. The hindwings are fuscous with a long, light fuscous fringe. Adults are on wing in late December. The larvae were recorded on Dombeya acutangula and Ruizia cordata, but these records are based on a misidentification of Phyllonorycter ruizivorus. They probably mine the leaves of their host plant.