An ant bug of the subfamily Holoptilinae (Reduviidae: Hemiptera), Praecoris dominicana gen. n., sp. n., is described in amber from the Dominican Republic. Based on the functional morphology of extant forms, the behavior of the fossil bug as an ant predator is discussed. This find clearly establishes the Holoptilinae in the New World during the Tertiary and gives credence to the single New World extant specimen reported from Guyana. It is likely that the prey of the fossil specimen was the arboreal ant, Dolichoderus dibolia. Both the bug and its ant prey are now extinct and no descendents occur in the Greater Antilles today.