Cyanocyclas brasiliana (Bivalvia: Cyrenidae) rediscovered in the limnic part of Parnaíba River delta, Northeast Brazil

Cyanocyclas brasiliana (Deshayes, 1854) known only from the original very short description and reported from Pará state was recently rediscovered. This is the first occurrence of a native species of Cyrenidae (formerly Corbiculidae) in the Northeast Region of Brazil. Due to a lack of previous data C. brasiliana was initially confused with Corbicula largillierti (Philippi, 1844), an invasive species of Asian origin, which was introduced in South America in the 1970s and already recorded from the North and Northeast regions of Brazil. Ecological aspects are described. To aid identification, type material was studied.