We describe a new species of Cordyligaster Macquart (Diptera: Tachinidae) from Area de Conservacion Guanacaste (ACG) in northwestern Costa Rica. Cordyligastercapellii sp. n., is described and photographed. All specimens of C.capellii were reared from Syngamiaflorella (Stoll, 1781) (Lepidoptera, Crambidae, Spilomelinae), a leaf-rolling caterpillar collected in ACG rain forest. By coupling morphology, photographic documentation, life history and molecular data, we provide a clear and concise description of this new species. In addition the authors provide new distribution and host records for C.fuscipennis (Macquart) reared in ACG.
Keywords: Cordyligaster; Crambidae; Diptera; Tachinidae; caterpillar inventory; host-specificity; parasitoid fly; tropical dry forest; tropical rain forest.