30 research outputs found
New species of Hasemania (Characiformes: Characidae) from Central Brazil, with comments on the endemism of upper rio Tocantins basin, GoiĂĄs State
Hasemania kalunga Ă© descrita para a bacia do alto rio Tocantins, Chapada dos Veadeiros, GoiĂĄs, Brasil. A espĂ©cie nova distingue-se das suas congĂȘneres pelo nĂșmero de escamas perfuradas da linha lateral (11-21 vs. 5-9, exceto de H. crenuchoides e H. piatan), pela presença de uma mancha umeral preta e verticalmente alongada (vs. ausĂȘncia, exceto de H. crenuchoides, H. nambiquara e H. piatan), e pela ausĂȘncia de escamas na base da nadadeira anal (vs. presença, exceto de H. maxillaris e H. piatan), por 19 raios principais na nadadeira caudal (vs.18 em H. piatan). Ela tambĂ©m difere de H. crenuchoides por dados morfomĂ©tricos. A ausĂȘncia de uma bainha de escamas cobrindo a base da nadadeira anal, um carĂĄter incomum em Characidae, e o endemismo da ictiofauna do alto rio Tocantins sĂŁo discutidos.Hasemania kalunga is described from the upper rio Tocantins basin, Chapada dos Veadeiros, GoiĂĄs State, Brazil. The new species is distinguished from its congeners by the number of perforated lateral line scales (11-21 vs. 5-9, except from H. crenuchoides and H. piatan), by the presence of a black vertically-elongate humeral spot (vs. absent, except from H. crenuchoides, H. nambiquara, and H. piatan), and by absence of scale sheath along anal-fin base (vs. presence, except from H. maxillaris, and H. piatan), by 19 principal caudal-fin rays (vs. 18 in H. piatan). It differs also from H. crenuchoides by morphometric data. The absence of scale sheath covering the anal-fin base, an uncommon character in Characidae, and the endemism of the ichthyofauna from the upper rio Tocantins are discussed
Molecular phylogeny of the subfamily Stevardiinae Gill, 1858 (Characiformes: Characidae): classification and the evolution of reproductive traits
Abstract
Background
The subfamily Stevardiinae is a diverse and widely distributed clade of freshwater fishes from South and Central America, commonly known as âtetrasâ (Characidae). The group was named âclade Aâ when first proposed as a monophyletic unit of Characidae and later designated as a subfamily. Stevardiinae includes 48 genera and around 310 valid species with many species presenting inseminating reproductive strategy. No global hypothesis of relationships is available for this group and currently many genera are listed as incertae sedis or are suspected to be non-monophyletic.
Results
We present a molecular phylogeny with the largest number of stevardiine species analyzed so far, including 355 samples representing 153 putative species distributed in 32 genera, to test the groupâs monophyly and internal relationships. The phylogeny was inferred using DNA sequence data from seven gene fragments (mtDNA: 12S, 16S and COI; nuclear: RAG1, RAG2, MYH6 and PTR). The results support the Stevardiinae as a monophyletic group and a detailed hypothesis of the internal relationships for this subfamily.
Conclusions
A revised classification based on the molecular phylogeny is proposed that includes seven tribes and also defines monophyletic genera, including a resurrected genus Eretmobrycon, and new definitions for Diapoma, Hemibrycon, Bryconamericus sensu stricto, and Knodus sensu stricto, placing some small genera as junior synonyms. Inseminating species are distributed in several clades suggesting that reproductive strategy is evolutionarily labile in this group of fishes.http://deepblue.lib.umich.edu/bitstream/2027.42/134621/1/12862_2015_Article_403.pd
Two new species of Odontostilbe historically hidden under O. microcephala (Characiformes: Cheirodontinae)
Specimens historically identified as Odontostilbe microcephala from the upper rio ParanĂĄ and Andean piedmont tributaries of the rĂo Paraguay are reviewed and split in three species. We found that the distribution of O. microcephala is restricted to the Andean slope of the rĂo Paraguay basin. The species is distinguished from congeners with subterminal mouth by the elongate body, usually 10-12 gill rakers on upper branch and smaller horizontal orbital diameter (24.6-32.8 % HL, mean 28.7%). Specimens from upper rio ParanĂĄ constitute two new species, diagnosed from other Cheirodontinae by the presence of mesopterygoid teeth, grouped on median portion and forming a continuous row. The new species are distinguished from each other by having premaxillary teeth with five cusps vs. nine cusps and by the number of lamellae in left and right sides of central median raphe of olfactory rosette with 20-21 vs. 11-12.EspĂ©cimes historicamente identificados com Odontostilbe microcephala do rio ParanĂĄ e tributĂĄrios do rĂo Paraguay, foram revisados e separados em trĂȘs espĂ©cies. A distribuição de O. microcephala Ă© restrita ao sopĂ© andino da bacia do rĂo Paraguay. A espĂ©cie Ă© distinta das congĂȘneres com boca subterminal pela forma alongada, geralmente 10-12 rastros branquiais no ramo superior e menor diĂąmetro horizontal da Ăłrbita (24,6-32,8 % CC, mĂ©dia 28,7%). EspĂ©cimes do alto rio ParanĂĄ constituem duas espĂ©cies novas diagnosticadas de outros Cheirodontinae pela presença de dentes no mesopterigoide, agrupados em sua porção mĂ©dia e formando uma fileira continua. As novas espĂ©cies distinguem-se por ter dentes premaxilares com cinco cĂșspides vs. nove cĂșspides e pelo nĂșmero de lamelas nos lados esquerdo e direito da rafe central da roseta olfativa com 20-21 vs. 11-12
A new Moenkhausia Eigenmann, 1903 (Ostariophysi: Characiformes) from Chapada Diamantina, rio Paraguaçu Basin, Bahia, Northeastern Brazil
One thousand DNA barcodes of piranhas and pacus reveal geographic structure and unrecognised diversity in the Amazon
Piranhas and pacus (Characiformes: Serrasalmidae) are a charismatic but understudied family of Neotropical fishes. Here, we analyse a DNA barcode dataset comprising 1,122 specimens, 69 species, 16 genera, 208 localities, and 34 major river drainages in order to make an inventory of diversity and to highlight taxa and biogeographic areas worthy of further sampling effort and conservation protection. Using four methods of species discovery - incorporating both tree and distance based techniques - we report between 76 and 99 species-like clusters, i.e. between 20% and 33% of a priori identified taxonomic species were represented by more than one mtDNA lineage. There was a high degree of congruence between clusters, with 60% supported by three or four methods. Pacus of the genus Myloplus exhibited the most intraspecific variation, with six of the 13 species sampled found to have multiple lineages. Conversely, piranhas of the Serrasalmus rhombeus group proved difficult to delimit with these methods due to genetic similarity and polyphyly. Overall, our results recognise substantially underestimated diversity in the serrasalmids, and emphasise the Guiana and Brazilian Shield rivers as biogeographically important areas with multiple cases of across-shield and within-shield diversifications. We additionally highlight the distinctiveness and complex phylogeographic history of rheophilic taxa in particular, and suggest multiple colonisations of these habitats by different serrasalmid lineages. © 2018 The Author(s)
Revisionary study of the armored catfish Corydoras paleatus (Jenyns, 1842) (Siluriformes: Callichthyidae) over 180 years after its discovery by Darwin, with description of a new species
Redescription and osteology of Hyphessobrycon compressus (Meek) (Teleostei: Characidae), type species of the genus
Molecular phylogeny of the subfamily Stevardiinae Gill, 1858 (Characiformes: Characidae): classification and the evolution of reproductive traits
A New Species of Hemigrammus from the Upper Rio TapajĂłs Basin in Brazil (Teleostei: Characiformes: Characidae)
Two new species of Hyphessobrycon (Teleostei: Characidae) from upper rio TapajĂłs basin on Chapada dos Parecis, central Brazil
Two new species of Hyphessobrycon are described from the upper rio TapajĂłs basin, Mato Grosso, Brazil. Hyphessobrycon melanostichos is distinguished from its congeners by the combination of a conspicuous longitudinal broad black band beginning on the posterior margin of orbit and reaching the tip of middle caudal fin rays, a distinct vertically elongate humeral spot, and 16 to 18 branched anal-fin rays. Hyphessobrycon notidanos is distinguished from its congeners by the combination of an elongate dorsal fin in mature males, a vertically elongate humeral spot, 2-4 maxillary teeth, iii,8 dorsal-fin rays, and 16 to 21 branched anal-fin rays