On Paranacypris samambaiensis gen. nov., sp. nov. (Crustacea,Ostracoda), the first South American psychrodromid from the alluvial valley of the Upper Paraná River,Brazil

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.