RESUMENLa fauna de crustáceos malacostráceos limnéticos, en el territorio de Chile continental, está compuesta por seis especies de camarones, i.e., cinco parastácidos de los géneros Parastacus, Samastacus y Virilastacus y un palemónido del género Cryphiops, 18 especies de anomuros del género Aegla, siete especies de anfípodos gamarídeos del género Hyallela y una especie de isópodo aselotano del género Heterias. La distribución conjunta abarca desde Arica a Punta Arenas, pero la mayor parte de las especies tiene rango geográfico restringido. La mayor densidad de taxa ocurre entre las regiones VIII y X, donde el número de taxa por Región varía entre 11 y 15, siendo la X Región la que tiene el número mayor. Índices derivados de un estudio sobre relaciones filogenéticas de las especies chilenas de Aegla, combinados con criterios propuestos por IUCN (2001), calificó a A. concepcionensis y A. expansa como especies Extintas y a A. papudo, A. l. laevis y A. spectabilis como Críticamente Amenazadas. Además, asignó máxima prioridad de conservación a la zona comprendida entre las cuencas del río Tucapel y del río Toltén. El estado de conservación de las especies de Parastacidae fue establecido por Bahamonde et al. (1998) y complementado por Rudolph & Crandall (2005). El estado de conservación de las especies de Hyalella y del isópodo Heterias exul no ha sido determinado. Se percibe que las amenazas a la conservación de las especies de malacostráceos limnéticos en Chile derivan principalmente de perturbaciones antropogénicas de la integridad y salud ambiental de las cuencas hidrográficas, particularmente entre las Regiones IV a VIII. PALABRAS CLAVES: Malacostráceos, diversidad, conservación, Amphipoda, Isopoda, Decapoda, Chile, limnología. ABSTRACTThe continental Chilean limnetic malacostracan fauna is currently composed of six species of crayfish / shrimp, i.e., five parastacids in the genus Parastacus, Samastacus and Virilastacus, and one palaemonid in the genus Cryphiops, eighteen species of anomuran crabs in the genus Aegla, seven species of gammaridean amphipods in the genus Hyalella, and one species of asellotan isopod in the genus Heterias. The distribution of the set of thirty one species of malacostracans spans from Arica in the north to Magallanes in the far south. However, most species have a restricted geographic range, comprising one or a few hydrographical contiguous basins along the latitudinal gradient. The largest concentration of malacostracan species is found between the VIII and X Administrative Regions of Chile; being the X the largest with fifteen taxa. Indices derived from a phylogenetic study concerning the relationship of the Chilean species of Aegla, and considering the conservation criteria proposed by UICN (2001), qualified A. concepcionensis and A. expansa as Extinct in the Wild, and A. papudo, A. l. laevis and A. spectabilis as Critically Endangered species. Furthermore, it assigned maximum conservation priority to the coastal area between the Tucapel and the Tolten rivers. The conservation ...

Aim To understand the ecological and historical/evolutionary processes underlying an inverse latitudinal gradient of richness (LGR) using crustacean peracarid species as a model group. LocationThe Pacific coast of South America, along the Chilean coast between 18°S and 56°S. MethodsThe LGR was evaluated using a dataset including 320 marine peracarid species reported for the coasts of Chile. Five ecological hypotheses invoking a relationship between species richness and present-day conditions were tested: species-energy, species-area, Rapoport rescue effect, mid-domain geometric constraint and niche breadth. Historical/evolutionary hypotheses (i.e. biogeographic conservatism, and diversification rates) were indirectly tested by analysing the latitudinal variation in the taxonomic distinctness, the taxonomic conservatism of the midpoint of the latitudinal range and the degree of nestedness at different taxonomic levels. ResultsRichness increased poleward, varying approximately eightfold, following an inverse LGR coupled with an increase in bathymetric distribution. Overall this inverse LGR seems robust to uncertainties in the completeness of the species inventory. We found support for only two of the five ecological hypotheses tested: species-area and Rapoport rescue effect. Historical/evolutionary hypotheses seemed important in structuring the richness pattern, as indicated by the higher taxonomic distinctness in the southern region, the strong taxonomic inertia in the mean range size and the high degree of nestedness of assemblages at different taxonomic levels.Conclusions When combined, these results underscore the importance of longterm processes and historical/evolutionary explanations for the inverse LGR, conceptualized in what we term the 'out of the deep south' hypothesis that involves the effects of both biogeographic niche conservatism and evolutionary rates. We propose that the southern region may be a source of evolutionary novelties and/or exhibit higher diversification rates (i.e. higher speciation/lower extinction rates). Furthermore, phylogenetic conservatism of latitudinal range may limit the geographic expansion of these new taxa towards the depauperated northern region.

The Chilean fauna of amphipods has been poorly studied.

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