NEOTROPICAL FRESHWATER FISHES: A dataset of occurrence and abundance of freshwater fishes in the Neotropics

The Neotropical region hosts 4225 freshwater fish species, ranking first among the world's most diverse regions for freshwater fishes. Our NEOTROPICAL FRESHWATER FISHES data set is the first to produce a large-scale Neotropical freshwater fish inventory, covering the entire Neotropical region from Mexico and the Caribbean in the north to the southern limits in Argentina, Paraguay, Chile, and Uruguay. We compiled 185,787 distribution records, with unique georeferenced coordinates, for the 4225 species, represented by occurrence and abundance data. The number of species for the most numerous orders are as follows: Characiformes (1289), Siluriformes (1384), Cichliformes (354), Cyprinodontiformes (245), and Gymnotiformes (135). The most recorded species was the characid Astyanax fasciatus (4696 records). We registered 116,802 distribution records for native species, compared to 1802 distribution records for nonnative species. The main aim of the NEOTROPICAL FRESHWATER FISHES data set was to make these occurrence and abundance data accessible for international researchers to develop ecological and macroecological studies, from local to regional scales, with focal fish species, families, or orders. We anticipate that the NEOTROPICAL FRESHWATER FISHES data set will be valuable for studies on a wide range of ecological processes, such as trophic cascades, fishery pressure, the effects of habitat loss and fragmentation, and the impacts of species invasion and climate change. There are no copyright restrictions on the data, and please cite this data paper when using the data in publications.

Iterative taxonomy reveals a new species of Trichomycterus Valenciennes 1832 (Siluriformes, Trichomycteridae) widespread in Rio Doce basin: a pseudocryptic of T. immaculatus

This paper reports on a new species of Trichomycterus from the Rio Doce basin. Unusually for new taxa in the genus during the past few decades, the new species is not narrowly endemic but instead widely distributed in its major drainage, the Rio Doce. The species has been collected and deposited in scientific collections for some years, but has been systematically misidentified as the more abundant Trichomycterus immaculatus or, to a lesser degree, as other morphologically similar species from south-eastern Brazil such as T. nigricans and T. pradensis. A combination of several morphological characteristics, such as vertebral number, pectoral-fin ray counts, pigmentation pattern and barcoding distance, were iteratively used and unambiguously distinguish the new species from all congeners. The present case reveals a pattern of diversity-discovery in which rare and narrowly endemic morphologically conspicuous species are discovered and described before visually inconspicuous taxa, even when the latter are more abundant and widespread. The morphological similarities among south-eastern Brazilian species with a uniform dark-grey color serve as basis for a brief discussion about the concepts of cryptic and pseudo-cryptic species in Trichomycterus and their consequences for potentially hidden diversity in the genus.