New occurrence of exotic mollusk Helisoma duryi (Wetherby, 1879) (Gastropoda: Planorbidae) in Maranhão State, Brazil

Abstract

The present study expands the distribution of Helisoma duryi (Wetherby, 1879) to Maranhão State, northeastern Brazil. The specimens were sampled in fish tank for commercial purposes. In the country, there are records in nine states and this new one raises the problem of the species bioinvasion in Brazil.