Freshwater ichthyofauna from Brazil Northeast region was considered as being poorly known until recent years, with a considerable number of publications becoming available in the last decade. The present study provides an inventory of freshwater fish species from the Paraíba do Norte River basin located in Paraíba State, Brazil. This inventory is intended to contribute to the of knowledge to the regional fish diversity, pre-transposition of the São Francisco River. Collecting data was obtained from ichthyological databases of both national and foreign institutions. A total of 47 freshwater fish species are registered within the Paraíba do Norte River basin, represented by 38 genera, 20 families and six orders. Characiformes, comprising 47% (22 species), Cichliformes, and Siluriformes are among the most representative orders, 19% (9 species) each, of total recorded species. Seven species of Cichliformes are reported as introduced species in this basin. Cyprinodontiformes and Gobiiformes also registered in this region and correspond to 5% (two species) and Gymnotiformes, Perciformes and Synbranchiformes, 2% (one species each) of total recorded species. Paraíba do Norte River basin stands out in the current national scenario as it comprises the first region from the Mid-Northeastern Caatinga freshwater ecoregion to receive water from the transposition of the São Francisco River. The current inventory is important as it provides scientific data related to the ichthyofauna of Paraíba do Norte River basin prior to the commencement of the river transposition process. An identification key is also given for the freshwater fish species of the region.

Analysis of the error associated with the subsampling of Chironomidae in an intermittent stream of semi-arid Brazil. Biota Neotropica.http://dx.doi.org/10.1590/1676-06032015003914Abstract: Chironomidae is a common family in freshwaters, often occurring at high densities, which hinders the processing of large samples, given that time and labor are usually limited. The present study aims at evaluating the extent of the error related with the subsampling of Chironomidae from a larger sample with regard to the size of the individuals between a sample and the subsample. A total of 9195 chironomids were collected from three sites in an intermittent stream. Samples were taken using a Dshaped net (250 mm) on eight occasions. Individuals from each sample were homogenized in a gridded Petri dish and coordinates from lines and columns were randomly drawn. Individuals from the assigned coordinates were selected until 100 individuals or 10% of the sample were chosen. Comparisons were made between the proportion of larger ( §5mm) and smaller individuals (,5mm) between the samples and subsamples, and it was established the correlation between the size of the error and the size of the sample, using the rank coefficient of Spearman. The highest error observed was 12.7%, meaning that the difference in larger individuals between the sample and subsample reached that value. However on six of the eight samples the error was below 3%. Spearman correlation showed no significance between the error observed and the size of the sample (r=0.38, p=0.35), meaning that larger samples will not yield larger error associated with the size of the individuals. The present study indicates that the subsampling technique used is capable of drawing a random subset of individuals from a sample of chironomids with regard to their size. This technique can be used in ecological or biomonitoring studies in order to reduce sample processing time without creating a bias in the analysis. Keywords: temporary pools, sampling effort, aquatic insects.