Limnetica 40

The spreading of non-indigenous crayfish species represents a major risk for freshwater ecosystems worldwide. They can influence several trophic levels, reach great abundances and carry foreign epibionts and parasites that may affect native fauna. The early detection and identification of the alien crayfish is crucial to avoid further problems once they are naturalized and/or they become invasive. Here we report the first occurrence of the Australian redclaw crayfish Cherax quadricarinatus on the Iberian Peninsula, constituting the westernmost record of the species in Europe. We present a comprehensive diagnosis and illustration of the species in order to facilitate its differentiation from the other crayfish species occurring in Iberia. Furthermore, we include brief notes on its biology and discuss plausible pathways of its introduction, its invasive potential and the possible impacts it may cause in native ecosystems.