ANASPIDACEA, BATHYNELLACEA (CRUSTACEA, SYNCARIDA), GENERALIZED TRACKS, AND THE BIOGEOGRAPHICAL RELATIONSHIPS OF SOUTH-AMERICA

The spatial evolution of South American Syncarida (Anaspidacea and Bat hynellacea) and related taxa is evaluated applying a panbiogeographic approach, where Ocean basins are used to identify major patterns of in tercontinental distribution. The Pacific basin, corresponding to a sou thern temperate track, is identified as the major evolutionary centre for Stygocaris (Stygocarididae), Bathynella (Bathynellidae), Atopobath ynella, and Chilibathynella (Parabathynellidae), whereas distribution of Nannobathynella (Bathynellidae) and Cteniobathynella (Parabathynell idae) is centred on the Atlantic Ocean, belonging to a northern tropic al track. It is concluded that the biotic origin of the South American Syncarida is complex, implying the existence of at least two ancestra l biotas. (C) 1998 The Norwegian Academy of Science and Letters.