We describe seven new species of Spathidexia (Diptera: Tachinidae) reared from Area de Conservación Guanacaste (ACG), northwestern Costa Rica. All were reared from -various species of ACG caterpillars during an ongoing inventory of caterpillars, their food plants and their parasitoids. By coupling morphology, photographic documentation, life history and molecular data, we provide a clear and concise description of each species. All are known to be previously undescribed as a result of a comprehensive study of the genus by DMW. Spathidexiaatripalpus sp. n., Spathidexiajuanvialesi sp. n., Spathidexiamarioburgosi sp. n., Spathidexialuisrobertogallegosi sp. n., Spathidexialuteola sp. n., Spathidexiahernanrodriguezi sp. n. and Spathidexiaaurantiaca sp. n. are all authored and described by Fleming and Wood. Minthodexiopsis Townsend is proposed by Wood as a new synonym of Spathidexia. A new combination proposed by Wood as a result of the new synonymy is S.flavicornis (Brauer & Bergenstamm) comb. n.
Keywords: Diptera; Spathidexia; Tachinidae; caterpillars; host-specificity; parasitoid fly; tropical dry forest; tropical rain forest.