Acanthurus monroviae is reported for the first time in European Atlantic waters. One adult specimen of this species was observed and photographed in the Arrábida Marine Park (Portugal, 38.43°N9.07°W) in December 2007. Short term temperature changes associated with warmer winters may favour the occurrence of vagrant individuals of tropical species in this temperate biogeographic transition zone. This area is considered an important ‘barometer' for studying the effects of climate change with possibly permanent expansions of the geographical ranges of these species.
