The New World genus Opsidia Coquillett is redefined and treated as a senior synonym of Opsidiotrophus Reinhard, syn. n. Opsidia metopioides Allen is considered a senior synonym of O. vittata Reinhard, syn. n., and three new Neotropical species are described: O. antillarum sp. n., O. jamaica sp. n., and O. oebalioides sp. n. A key and diagnostic illustrations for all species are provided.