Catalogue for identification of the most common lacustrine and riverine cyclopoid copepod (Crustacea) species in plankton of La Plata Basin, South America

ABSTRACT A practical guide for the taxonomic identification of 25 species and subspecies of free-living cyclopoid copepods from the La Plata Basin, the second largest river basin in South America, is presented. Samples were collected at 43 sites across the main river sub-basins and selected reservoirs during the rainy and dry seasons of 2010. We also provide a key for the identification of female cyclopoid copepods, taxonomic diagnoses with general remarks for each species, drawings, digital photographs, and scanning electron micrographs. Considering all the cyclopoids known from different habitats in South America (i.e., groundwater, phytotelmata, mosses, interstitial), our inventory of free-living planktonic and littoral species accounts for approximately 30% of the total cyclopoid diversity known in South America. This guide offers unprecedented coverage in terms of taxonomic data, and illustrations of American free-living cyclopoids. It will be a useful laboratory tool for limnologists and biologists.