We report the first occurrence of Phragmatopoma caudata Krøyer in Mörch, 1863 in Piauí state, Brazil. This is the first record of this species in the APA Delta do Parnaíba, a national environmental protection area that comprises areas from 3 Brazilian states, Maranhão, Piauí and Ceará. This is also the northernmost and westernmost record of this species in Brazil to date, further extending by 415 km its known distribution in Brazil, and helping to fill a gap on the knowledge of its distribution in South America.