We describe three new species in the genus Ametadoria Townsend from Area de Conservación Guanacaste (ACG), Costa Rica. All three were reared from wild-caught Zygaenidae and Lacturidae caterpillars. We provide a concise description of each species using morphology, life history and molecular data, with photographic documentation. The new species are authored and described by Fleming and Wood: Ametadoria karolramosae sp. nov., Ametadoria leticiamartinezae sp. nov., and Ametadoria mauriciogurdiani sp. nov. The following are proposed by Wood as new synonyms of Ametadoria Townsend: Adidyma Townsend syn. nov., and Abolodoria Townsend syn. nov. The following new combinations occur as a result of these new synonymies: Ametadoria abdominalis (Townsend) comb. nov., Ametadoria austrina (Coquillett) comb. nov., Ametadoria humilis (Wulp) comb. nov., Ametadoria misella (Wulp) comb. nov. Ametadoria adversa (Townsend) is proposed as a junior synonym of Ametadoria unispinosa Townsend, syn. nov.