15 research outputs found
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
Species delimitation in sharpnose sharks (genus Rhizoprionodon) in the western Atlantic Ocean using mitochondrial DNA
Despite Springerâs (1964) revision of the sharpnose sharks (genus Rhizoprionodon), the taxonomic
definition and ranges of Rhizoprionodon in the western Atlantic Ocean remains problematic. In particular, the distinction
between Rhizoprionodon terraenovae and R. porosus, and the occurrence of R. terraenovae in South
American waters are unresolved issues involving common and ecologically important species in need of fishery management
in Caribbean and southwest Atlantic waters. In recent years, molecular markers have been used as efficient
tools for the detection of cryptic species and to address controversial taxonomic issues. In this study 415 samples of
the genus Rhizoprionodon captured in the western Atlantic Ocean from Florida to southern Brazil were examined for
sequences of the COI gene and the D-loop and evaluated for nucleotide differences. The results on nucleotide
composition, AMOVA tests, and relationship distances using Bayesian-likelihood method and haplotypes network,
corroborates Springerâs (1964) morphometric and meristic finding and provide strong evidence that supports consideration
of R. terraenovae and R. porosus as distinct species.info:eu-repo/semantics/publishedVersio