Botanical exploration in southwestern Amazonia has revealed a new species, Spondias testudinis J. D. Mitch. & Daly, described and illustrated here. Its distribution appears to be restricted to the Brazilian state of Acre; Pando in Bolivia; and Huanuco and Ucayali in Peru. The sexuality of the flowers of Spondias and its implications regarding their morphology is discussed. A provisional key to the neotropical species is presented.