Los crustáceos decápodos del Atlántico sudoccidental (25o-55oS): distribución y ciclos de vida

a number of 243 species of decapod crustaceans, belonging to 49 families, were found in the southwestern atlantic, between 25 and 55°s. suborder dendrobranchiata includes 6 families with 23 species. suborden pleocyemata has 10 families of caridea with 35 species, 1 family of astacidea with 2 species, 1 family of palinura with 1 species, 2 families of thalassinidea with 7 species, 8 families of anomura with 44 species and 21 families of brachyura with 131 species. in the warm-temperate region of the southwestern atlantic there are 200 species; 73% of them spread to the north ("tropical species"), 27% are found between río de janeiro and tierra del fuego. from these species, 44 are endemic. the number of tropical species diminishes at higher latitudes, although different families show different patterns; environmental changes at 29o-35°s, mainly the fall in winter temperatures and the effects of la plata river, seem to limit their southern spread. cold-temperate region is represented by 39 species; 24 of them also inhabited the southern pacífic ocean. many cold-temperate species (50%) reach lower latitudes in the atlantic (42°s or less), but in deep waters. information on geographic distribution, life cycles, and economic importance of warm-temperate species is given. the atlantic and pacific decapod fauna of southern south america have a similar number of species and families, but differences in their composition are detected