A new species of Tethocyathus is described, T. prahli, characterized by having a tympaniform corallum shape and no fossa. Specimens were found living at 310 m in the Colombian Caribbean, 303–333 m at Cocos Island (Pacific Costa Rica), and from the early Pleistocene of Pacific Panama, sug-gesting a relictual distribution of a previously more widespread species. Teth-ocyathus prahli is probably unique among the Scleractinia in having a noncosmopolitan trans-isthmian distribution. The diagnosis of the genus