Trichomycteridae is the second most diverse family of the order Siluriformes, its members are widely distributed through the freshwaters of Central and South America, exhibiting an exceptional ecological and phenotypic disparity. The most diverse subfamily, Trichomycterinae, represented mainly by the genus Trichomycterus, historically has been recognized as non-monophyletic and various characters used to unite or divide its constituents are repeatedly called into question. No comprehensive molecular phylogenetic hypothesis regarding relationships of trichomycterids has been produced, and the present study is the first extensive phylogeny for the family Trichomycteridae, based on a multilocus dataset of three mitochondrial loci and two nuclear markers (3284bp total). Our analysis has the most comprehensive taxon-sampling of the Trichomycteridae published so far, including members of all subfamilies and a vast representation of Trichomycterus diversity. Analysis of these data showed a phylogenetic hypothesis with broad agreement between the Bayesian (BI) and maximum-likelihood (ML) trees. The results provided overwhelming support for the monophyletic status of Copionodontinae, Stegophilinae, Trichomycterinae, and Vandelliinae, but not Sarcoglanidinae and Glanapteryginae. A major feature of our results is the support to the current conceptualization of Trichomycterinae, which includes Ituglanis and Scleronema and excludes the "Trichomycterus" hasemani group. Divergence time analysis based on DNA substitution rates suggested a Lower Cretaceous origin of the family and the divergence events at subfamilial level shaped by Paleogene events in the geohistory of South America. This hypothesis lays a foundation for an array of future studies of evolution and biogeography of the family.

The Neotropics harbor the most species-rich freshwater fish fauna on the planet, but the timing of that exceptional diversification remains unclear. Did the Neotropics accumulate species steadily throughout their long history, or attain their remarkable diversity recently? Biologists have long debated the relative support for these museum and cradle hypotheses, but few phylogenies of megadiverse tropical clades have included sufficient taxa to distinguish between them. We used 1,288 ultraconserved element loci (UCE) spanning 293 species, 211 genera and 21 families of characoid fishes to reconstruct a new, fossil-calibrated phylogeny and infer the most likely diversification scenario for a clade that includes a third of Neotropical fish diversity. This phylogeny implies paraphyly of the traditional delimitation of Characiformes because it resolves the largely Neotropical Characoidei as the sister lineage of Siluriformes (catfishes), rather than the African Citharinodei. Time-calibrated phylogenies indicate an ancient origin of major characoid lineages and reveal a much more recent emergence of most characoid species. Diversification rate analyses infer increased speciation and decreased extinction rates during the Oligocene at around 30 million years ago (Ma) during a period of mega-wetland formation in the proto-Orinoco-Amazonas. Three species-rich and ecomorphologically diverse lineages (Anostomidae, Serrasalmidae, and Characidae) that originated more than 60 Ma in the Paleocene experienced particularly notable bursts of Oligocene diversification and now account collectively for 68% of the approximately 2,150 species of Characoidei. In addition to paleogeographic changes, we discuss potential accelerants of diversification in these three lineages. While the Neotropics accumulated a museum of ecomorphologically diverse characoid lineages long ago, this geologically dynamic region also cradled a much more recent birth of remarkable species-level diversity.

Cryptic species in the Neotropical fish genus Curimatopsis (Teleostei, Characiformes). -Zoologica Scripta, 00, 000-000. Detritivores of the fish family Curimatidae are assigned to eight genera, one of which, the Curimatopsis, with only five species, is the least speciose genus and sister to other seven genera in the family. Ongoing morphological investigations reveal, however, the likely existence of additional species. In this study, fifty-one specimens of Curimatopsis from multiple rivers of the Amazon, Paraguay and Suriname drainages were identified morphologically according to the present species concepts and then barcoded using the universal cytochrome c oxidase subunit I (COI) mitochondrial marker. Species delimitation analyses were conducted using Bayesian methods through the general mixed Yule-coalescent analysis combined with conventional likelihood, genetic distance and haplotypic diversity approaches. We found eleven well-supported clusters that represent four of the named species and seven cryptic, undescribed species of Curimatopsis. Our results show a clear delimitation of species boundaries constrained by distinct Amazonian river ecotones that may have promoted intrageneric lineage diversification. This is the first of a series of genetic studies applicable to future taxonomic, phylogenetic and evolutionary studies across the Curimatidae.

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