South America is neither the largest nor the most populated continent, but it is the most diverse, holding fi ve of the world’s biodiversity hotspots, as well as the biggest tropical wilderness on Earth (Conservation International). The South American continent comprises an area of 17,85 million km2 and is a very rich region in terms of wetland ecosystems (Junk 2013), in which a huge biodiversity and endemism in different taxonomic groups has been identifi ed (Tisseuil et al. 2013). One of these groups is, undoubtedly, freshwater crustaceans, especially decapods like shrimps, crabs, freshwater false crabs and crayfi shes (Melo 2003, Lévêque et al. 2005, Bond-Buckup et al. 2008, De Grave et al. 2008, Rudolph 2013b). The native South American crayfi sh (Family Parastacidae) is a very intriguing crustacean group in view of some peculiarities like distribution (very endemic group), habitat (burrowers living underground), reproductive strategies (many species are hermaphroditic) and ecological functions (keystone trophic regulators and ecological engineers). Although native South American crayfi sh is still a group with many knowledge defi ciencies, in the last three decades, much data has been accumulated in different aspects of its natural history. The increasing number of threats against wetland ecosystems, as well as the pressing biodiversity loss in this ecosystem, deserves attention. The current conservation status for native crayfi sh indicates that in the near future species may be extinct if conservation measures are not taken. This chapter is divided into six sections (Diversity and taxonomy, Phylogeny, Biogeography and
1 Department of Biological Sciences and Biodiversity, University of Los Lagos, Casilla 933, Osorno, Chile.