The Asian green mussel, Perna viridis, is a globally successful invasive bivalve first recorded in the South Atlantic in 2018. Here, we report and characterize the establishment of P. viridis in the Canal do Itajurú, a coastal channel connecting the hypersaline Araruama Lagoon to the Atlantic Ocean in Rio de Janeiro, Brazil. We assessed its spatial distribution, substrate association, and morphometric variation to evaluate local establishment and potential ecological and management implications.
