Abstract
Paranacypris samambaiensis gen. nov., sp. nov. is here described from closed lakes in the alluvial valley of the Upper Paraná River. The new genus, characterized by a large frontally overlapping left valve, belongs in the Psychrodromini, and is the first representative of this tribe described in South America. Nevertheless, it has some different character states, and the diagnosis of the tribe had to be adapted. The species is rare and restricted to closed lakes (not in contact with the main channels of the river). It mostly occurs in benthic littoral habitats, and far less in the pleuston communities, the most common habitat in this floodplain. The behaviour of P. samambaiensis gen. nov., sp. nov. is enigmatic because it combines long natatory setae on the antennae (swimming behaviour) with a very stout caudal ramus, including the spine‐like posterior seta (crawling behaviour). We present a key to the genera of the Herpetocypridinae.
Acknowledgements
J.H. acknowledges Dr Ricardo L. Pinto for his patience and help with the drawings; Dr Carlos E. F. Rocha for allowing the use of all facilities in his laboratory; Dr. Luiz Felipe M. Velho and Dr Fábio A. Lansac Tôha for many suggestions and discussions. Sukonthip Savatenalinton and Karel Wouters (Brussels, Belgium) read the manuscript and suggested improvements. Julian Cillis and Claudine Behen offered technical assistance with the scanning electron microscopy and the line drawings respectively. Jaime Luiz Lopes Pereira (Maringá, Brazil) offered help with the map. J.H. received a grant to do her postdoctoral thesis in the Royal Belgian Institute of Natural Sciences (Brussels, Belgium) from CAPES (Processo: BEX1452/08‐8). This research is part of a series of projects supported by CNPq (Processo: 472434/03‐9), CNPq/PELD and Nupélia. We thank the two anonymous referees for their helpful comments.