The new species Satanoperca rhynchitis occurs in French Guiana in the Oyapock, Approuague, Comté, Kourou, Sinnamary and Iracoubo river drainages. It is distinguished from congeneric species in particular by lower meristics and a longer snout, probably also by red lips in life. Samples of Satanoperca from Amapá state in Brazil fall into two groups, one probably representing the Amazonian S. jurupari, and the other resembling S. rhynchitis but with shorter snout. Species assignation of Amapá samples is not definite because of small sample sizes. Rio Amapá samples and coastal specimens from French Guiana may represent introgression of the Amazonian S. jurupari.