AEGLA BAHAMONDEI, NEW SPECIES (CRUSTACEA: DECAPODA: ANOMURA) FROM THE COASTAL MOUNTAIN RANGE OF NAHUELBUTA, CHILE

Abstract

Aegla bahamondei, new species (Crustacea, Anomura, Aeglidae) is described from the Tucapel River on the western slope of Cordillera de Nahuelbuta, Chile. Morphologically it closely resembles A. rostrata Jara from preandean lakes of the Valdivia and Tolten river basins. A. bahamondei differs from A. rostrata in its acute median tubercle on the fourth thoracic sternum, less prominent overall spinulation, and nonstilettolike rostrum. The morphological similarity between A. bahamondei and A. rostrata is interpreted as indication of recent common ancestry. It is hypothesized that A. bahamondei represents the plesiomorphic and A. rostrata the apomorphic species. The Chilean coastal mountain range of Nahuelbuta, stretching between 37? and 39?, is a region of faunistic individuality compared with the remaining southern Chilean territory. This view is supported by the existence of at least two genera of Plecoptera (Insecta) and one species of Anura restricted to this region (Illies, 1969; Formas, 1979); these authors presume that the Cordillera de Nahuelbuta served as a refuge for the preglacial Tertiary fauna. Arenas (1976) has suggested that in postglacial times some freshwater fishes and amphibians could have extended their geographic range from this coastal refuge to the Andes. Four species of crayfishes (Parastacidae) and three species of Aeglidae (Bahamonde and L6pez, 1963; Jara, 1977) are known from freshwaters in the Chilean region between Concepci6n and Valdivia provinces. However, none of the Aegla species have been recorded from the Cordillera de Nahuelbuta itself or from its immediate surroundings. This paper describes as a new species a form of Aegla Leach found in a small river on the western slope of the Cordillera de Nahuelbuta.