Penaeus aztecus Ives, 1891 (Crustacea, Decapoda), in the Scheldt estuary (Belgium): Isolated record or forerunner of a penaeid invasion?

A single specimen of the penaeid prawn Penaeus aztecus (Ives, 1891) was recorded in 2018 in the brackish zone of the Scheldt estuary near Antwerp (Belgium). The presence of this species, native to the West Atlantic, might result either from ships' ballast water coming from transatlantic boat shipping, from illegal import or from a considerable expansion leap northwards from the Mediterranean Sea, where this species has recently established and now has rapidly expanding invasive populations.