BackgroundWith nearly 1,100 species, the fish family Characidae represents more than half of the species of Characiformes, and is a key component of Neotropical freshwater ecosystems. The composition, phylogeny, and classification of Characidae is currently uncertain, despite significant efforts based on analysis of morphological and molecular data. No consensus about the monophyly of this group or its position within the order Characiformes has been reached, challenged by the fact that many key studies to date have non-overlapping taxonomic representation and focus only on subsets of this diversity.ResultsIn the present study we propose a new definition of the family Characidae and a hypothesis of relationships for the Characiformes based on phylogenetic analysis of DNA sequences of two mitochondrial and three nuclear genes (4,680 base pairs). The sequences were obtained from 211 samples representing 166 genera distributed among all 18 recognized families in the order Characiformes, all 14 recognized subfamilies in the Characidae, plus 56 of the genera so far considered incertae sedis in the Characidae. The phylogeny obtained is robust, with most lineages significantly supported by posterior probabilities in Bayesian analysis, and high bootstrap values from maximum likelihood and parsimony analyses.ConclusionA monophyletic assemblage strongly supported in all our phylogenetic analysis is herein defined as the Characidae and includes the characiform species lacking a supraorbital bone and with a derived position of the emergence of the hyoid artery from the anterior ceratohyal. To recognize this and several other monophyletic groups within characiforms we propose changes in the limits of several families to facilitate future studies in the Characiformes and particularly the Characidae. This work presents a new phylogenetic framework for a speciose and morphologically diverse group of freshwater fishes of significant ecological and evolutionary importance across the Neotropics and portions of Africa.

Much progress has been achieved in disentangling evolutionary relationships among species in the tree of life, but some taxonomic groups remain difficult to resolve despite increasing availability of genome-scale data sets. Here we present a practical approach to studying ancient divergences in the face of high levels of conflict, based on explicit gene genealogy interrogation (GGI). We show its efficacy in resolving the controversial relationships within the largest freshwater fish radiation (Otophysi) based on newly generated DNA sequences for 1,051 loci from 225 species. Initial results using a suite of standard methodologies revealed conflicting phylogenetic signal, which supports ten alternative evolutionary histories among early otophysan lineages. By contrast, GGI revealed that the vast majority of gene genealogies supports a single tree topology grounded on morphology that was not obtained by previous molecular studies. We also reanalysed published data sets for exemplary groups with recalcitrant resolution to assess the power of this approach. GGI supports the notion that ctenophores are the earliest-branching animal lineage, and adds insight into relationships within clades of yeasts, birds and mammals. GGI opens up a promising avenue to account for incompatible signals in large data sets and to discern between estimation error and actual biological conflict explaining gene tree discordance.

The overall most parsimonious hypothesis of relationships based on 200 characters indicates that the Alestidae is the closest relative of Chalceus, a genus previously assigned to the Neotropical Characidae. Chalceus is shifted into the Alestidae, which becomes the only trans‐Atlantic family level group within the Characiformes. Various previously proposed suprageneric assemblages within the Alestidae (e.g. Petersiini) failed to delimit monophyletic groups under the intrafamilial phylogenetic analysis. The evaluation of fossil alestids within the context of the phylogeny indicates that the ancestors of Alestes, Arnoldichthys, Brycinus, Bryconaethiops and Hydrocynus evolved prior to the early Eocene (Cuisian of Upper Ypresian), 49–54.8 million years ago, with the fossil Alestoides most closely related to Alestes. The phylogenetic information further indicates a minimum age of 90–112 million years for the Alestidae. Contrary to previous hypotheses, the fossil African Sindacharax was found to be most similar to the clade including the alestid genus Bryconaethiops rather than most closely related to the South American subfamily Serrasalminae. Evaluation of the fossil Mahengecharax carrolli fails to support its hypothesized placement as the sister group to all Recent members of the Alestidae. Two separate episodes of miniaturization and one episode of gigantism occurred within the evolution of the Alestidae. © 2005 The Linnean Society of London, Zoological Journal of the Linnean Society, 2005, 145, 1−144. No claim to original US government works.

Vari, Richard P. The Neotropical Fish Family Ctenoluciidae (Teleostei: Ostariophysi: Characiformes): Supra and Intrafamilial Phylogenetic Relationships, with a Revisionary Study. Smithsonian Contributions to Zoology, number 564, 97 pages, 51 figures, 12 tables, 1995.-Osteological and soft anatomical features of the species of the Neotropical characiform family Ctenoluciidae and other characiforms were studied to examine the hypothesis that the family was monophyletic, and to advance an hypothesis of phylogenetic relationships within the family and of the Ctenoluciidae to proximate outgroups. A series of derived features corroborate the hypothesis of monophyly of the Ctenoluciidae and are congruent with the hypothesis that the Ctenoluciidae and Erythrinidae are sister groups. A less-extensive series of derived features indicate that the African family Hepsetidae is the sister group of the clade formed by the Ctenoluciidae and Erythrinidae, with the Neotropical family Lebiasinidae the sister group to the clade formed by those three families. Shared derived features of a variety of body systems define phylogenetic subunits of the Ctenoluciidae and characterize the majority of its species. The ctenoluciid genera Ctenolucius Gill (1861a) and Boulengerella Eigenmann (1903) are defined as monophyletic units. Luciocharax Steindachner (1878) and Belonocharax Fowler (1907) are considered synonyms of Ctenolucius, with Spixostoma Whitley (1951) placed as a synonym of Boulengerella. Two species are recognized in Ctenolucius. Ctenolucius hujeta (Valenciennes in Cuvier and Valenciennes, 1849) ranges from the Lago Maracaibo basin of northwestern Venezuela through the Rfo Magdalena system to the Rio Sinu of northwestern Colombia. Ctenolucius beani (Fowler, 1907) occurs in the Rio Atrato and Rio San Juan basins of northwestern Colombia and the rivers of the Pacific slopes of Panama as far west as Veraguas Province. Luciocharax insculptus Steindachner (1878) is a synonym of C. hujeta, and Luciocharax striatus Boulenger (1911) is a synonym of C. beani. Five species are recognized in Boulengerella. Boulengerella lateristriga (Boulenger, 1895) occurs in the Rio Negro drainage of the Amazon basin in Brazil and Venezuela and uppermost portions of the Rio Orinoco in southern Venezuela. Boulengerella maculata (Valenciennes in Cuvier and Valenciennes, 1849) is widely distributed through the Rio Amazonas, Rio Tocantins, and Rio Orinoco basins. Boulengerella lucius (Cuvier, 1819) occurs in the Rio Amazonas and Rio Orinoco systems. Boulengerella cuvieri (Agassiz in Spix and Agassiz, 1829) is widespread through the Rio Orinoco, Rio Amazonas, and Rio Tocantins basins, the Essequibo River of Guyana, the Oyapock River along the boundary between French Guiana and Brazil, and the coastal rivers of Amapd and Par£ states in Brazil. Boulengerella xyrekes, new species, a relatively rare form, inhabits the Rio Orinoco and Rio Amazonas basins. Xiphostoma taedo Cope (1872) is a synonym of B. maculata. Xiphostoma oseryi Castelnau (1855) and Xiphostoma ocel...

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SERIES PUBLICATIONS OF THE SMITHSONIAN INSTITUTION Emphasis upon publication as a means of "diffusing knowledge" was expressed by the first Secretary of the Smithsonian. In his formal plan for the Institution, Joseph Henry outlined a program that included the following statement: "It is proposed to publish a series of reports, giving an account of the new discoveries in science, and of the changes made from year to year in all branches of knowledge." This theme of basic research has been adhered to through the years by thousands of titles issued in series publications under the Smithsonian imprint, commencing with Smithsonian Contributions to Knowledge in 1848 and continuing with the following active series: Smithsonian Contributions to Anthropology Smithsonian Contributions to Astrophysics Smithsonian Contributions to Botany Smithsonian Contributions to the Earth Sciences Smithsonian Contributions to the Marine Sciences Smithsonian Contributions to Paleobiology Smithsonian Contributions to Zoo/ogy Smithsonian Studies in Air and Space Smithsonian Studies in History and Technology In these series, the Institution publishes small papers and full-scale monographs that report the research and collections of its various museums and bureaux or of professional colleagues in the world of science and scholarship. The publications are distributed by mailing lists to libraries, universities, and similar institutions throughout the world. Papers or monographs submitted for series publication are received by the Smithsonian Institution Press, subject to its own review for format and style, only through departments of the various Smithsonian museums or bureaux, where the manuscripts are given substantive review. Press requirements for manuscript and art preparation are outlined on the inside back cover.

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