Tertiary freshwater Decapoda (Crustacea: Parastacidae) from the Ñirihuau Basin, Patagonia, Argentina

Abstract

Very well preserved specimens of a macruran decapod from the Lower (Lacustrine) Member of the Ñirihuau Formation, northwestern Patagonia, Argentina, permitted description of Lammuastacus longirostris, a new genus and species of Parastacidae. The sedimentological and paleontological evidences provided by the faunal assemblage indicate a freshwater environment. This is the first certain record of a fossil Parastacidae from Tertiary deposits, most probably Oligocene. The fossil material shows similarities with Geocharax, the extant Australian genus considered to retain many primitive characters, and other related genera from New Zealand and Chile.