Model-based Total Evidence phylogeny of Neotropical electric knifefishes (Teleostei, Gymnotiformes) (original) (raw)
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Copeia, 2000
This paper summarizes information on the South American freshwater gymnotiform genus Sternarchorhynchus Castelnau (family Apteronotidae), especially taxonomic and systematic. Sternarchorhynchus britskii and S. mesensis are described as new from the upper portions of the Rio Paraná and Rio Tocantins (Brazil), respectively. The new species are distinguished from currently recognized species by morphometric and meristic features such as the relative sizes of structures in head, size of pectoral fin, and number of anterior unbranched anal fin rays. The two new species, along with S. curvirostris (Boulenger) and S. roseni Mago-Leccia, are hypothesized to comprise a monophyletic subunit, tentatively recognized herein as the ''Sternarchorhynchus curvirostris group,'' based on the color pattern of anal and pectoral fins. Species relationships within Sternarchorhynchus are discussed. Este trabalho resume informações sobre o gênero sul-americano de Gymnotiformes Sternarchorhynchus Castelnau (família Apteronotidae), especialmente taxonômicas e sistemáticas. Sternarchorhynchus britskii e S. mesensis são descritas como novas das porções superiores dos rios Paraná e Tocantins (Brasil), respectivamente. As novas espécies são separadas das demais espécies válidas atualmente incluídas no gênero com base em características morfométricas e merísticas tais como, por exemplo, o tamanho relativo de estruturas na cabeça, nadadeira peitoral e nú mero de raios anteriores indivisos da nadadeira anal. Estas duas novas espécies, juntamente com S. curvirostris (Boulenger) e S. roseni Mago-Leccia, são supostas como compreendendo uma subunidade monofilética reconhecida aqui de maneira tentativa como o ''grupo Sternarchorhynchus curvirostris'' com base em padrões de coloração das nadadeiras anal e peitoral. Relações entre as espécies de Sternarchorhynchus são discutidas.
PloS one, 2016
A species-level phylogenetic reconstruction of the Neotropical bluntnose knifefish genus Brachyhypopomus (Gymnotiformes, Hypopomidae) is presented, based on 60 morphological characters, approximately 1100 base pairs of the mitochondrial cytb gene, and approximately 1000 base pairs of the nuclear rag2 gene. The phylogeny includes 28 species of Brachyhypopomus and nine outgroup species from nine other gymnotiform genera, including seven in the superfamily Rhamphichthyoidea (Hypopomidae and Rhamphichthyidae). Parsimony and Bayesian total evidence phylogenetic analyses confirm the monophyly of the genus, and identify nine robust species groups. Homoplastic osteological characters associated with diminutive body size and occurrence in small stream habitats, including loss of squamation and simplifications of the skeleton, appear to mislead a phylogenetic analysis based on morphological characters alone-resulting in the incorrect placing of Microsternarchus + Racenisia in a position deepl...
Karyotypic Diversity and Evolution in a Sympatric Assemblage of Neotropical Electric Knifefish
Frontiers in genetics, 2018
Chromosome changes can perform an important role in speciation by acting as post-zygotic reproductive barriers. The Neotropical electric fish genus (Gymnotiformes, Hypopomidae) has 28 described species, but cytogenetic data are hitherto available only for four of them. To understand karyotype evolution and investigate the possible role of chromosome changes in the diversification of this genus, we describe here the karyotype of eight species of from a sympatric assemblage in the central Amazon basin. We analyzed cytogenetic data in the context of a phylogenetic reconstruction of the genus and known patterns of geographical distribution. We found a strong phylogenetic signal for chromosome number and noted that sympatric species have exclusive karyotypes. Additional insights into the role of chromosome changes in the diversification of are discussed.
Zoologica Scripta, 2014
. Akawaio penak, a new genus and species of Neotropical electric fish (Gymnotiformes, Hypopomidae) endemic to the upper Mazaruni River in the Guiana Shield. -Zoologica Scripta, 00, 000-000. Akawaio penak, a new genus and species, is described from the upper Mazaruni River, Guyana. The new species is diagnosed from all other species of Hypopomidae by several anatomical traits. The phylogenetic affinities of the new genus were inferred using data from one nuclear (rag2) and two mitochondrial (COI and cyt b) genes. The phylogenetic analyses indicate that Akawaio is the sister taxon of a clade that includes Brachyhypopomus, Hypopomus, Microsternarchus and Racenisia. These results provide evidence for the phylogenetic composition of Hypopomidae supported by previous molecular studies and support the position of the Steatogenini (Hypopygus + Steatogenys) as the sister group of Rhamphichthys + Gymnorhamphichthys. The description of this new electric knifefish increases the total number of endemic genera and species in the upper Mazaruni, a region that is suffering freshwater habitat degradation as consequence of gold-mining activities.
2012
Neotropical electric knifefishes of the family Sternopygidae previously considered to represent a single relatively geographically widespread and morphologically variable species, Archolaemus blax, were analysed and found to represent a complex of five species, four of which are new to science. A fifth undescribed species from the Rio São Francisco basin outside the previous known range of the genus was identified. Recognized species of Archolaemus are: A. blax, previously thought to occur in the Rio Araguari, Rio Branco, Rio Tapajós, Rio Tocantins, and Rio Xingu, but which instead proved to be endemic to the Rio Tocantins; Archolaemus ferreirai sp. nov. from the Rio Mucajaí and Rio Uraricoera in the northeastern portions of the Amazon basin; Archolaemus janeae sp. nov. of the Rio Xingu and the upper Rio Tapajós, both southern tributaries of the mainstream Amazon; Archolaemus luciae sp. nov. of the Rio Trombetas, Rio Jari, and Rio Tapajós basins of the eastern Amazon, and the independent Rio Araguari draining into the Atlantic Ocean north of the mouth of the Amazon; Archolaemus orientalis sp. nov. of the São Francisco basin in eastern Brazil; and Archolaemus santosi sp. nov. of the Rio Jamari in the southwestern portion of the Amazon basin. The phylogenetic placements of Archolaemus and the recently described genus Japigny relative to the other members of the Eigenmanninae are discussed. A series of synapomorphies for Archolaemus are proposed and a hypothesis of the relationships within that genus is advanced. Rheophily of all members of Archolaemus is discussed, with the genus found to be the most specious clade within the Gymnotiformes living primarily in high-energy settings. The reported anterior projection of the dentary teeth in A. blax was found to be a consequence of postmortem displacement.
Zoological Journal of the Linnean Society, 2015
The pseudotympanum, a reduction of the hypaxialis muscle in the body wall lateral to the anterior portion of the swim bladder, is unique to some members of the Otophysi, the largest clade of primarily freshwater fishes. Prior studies documented the presence of the pseudotympanum in a number of groups within the Characiformes, to a lesser extent in subunits of the Siluriformes, and in a few taxa of the Cypriniformes, but with only one record of the aperture in the Gymnotiformes-the Neotropical electric fishes. Surveys across the five families and c. twothirds of the genera in the Gymnotiformes revealed the occurrence of a pseudotympanum in all examined taxa. Pronounced variation in the expanse and details of the morphology of the opening and its relationship to the anterior elements of the axial skeleton was documented amongst Neotropical electric fish. Details of pseudotympanal morphology in the different families of the Gymnotiformes are described and the variation evaluated within the context of the two alternative hypotheses of higher-level phylogenetic relationships within the order.
Three complete mitochondrial genomes of South American electric fishes (Gymnotiformes), derived from high-throughput RNA sequencing (RNA-Seq), are reported herein. We report the complete mitochondrial genome of the bluntnose knifefish Brachyhypopomus n.sp. VERD, determined from newly sequenced data. We also provide the complete mitochondrial genomes for Sternopygus arenatus and the electric eel Electrophorus electricus, assembled from previously published transcriptome data. The mitochondrial genomes of Brachyhypopomus n.sp. VERD, Sternopygus arenatus and Electrophorus electricus have 13 protein-coding genes, 1 D-loop, 2 ribosomal RNAs and 22 transfer RNAs, and are 16,547, 16,667 and 16,906 bp in length, respectively. Phylogenetic analysis of the eight available mitochondrial genomes of gymnotiform fishes shows Apteronotus to be the sister lineage of other gymnotiformes, contradicting the ''Sinusoidea'' hypothesis that Apteronotidae and Sternopygidae are sister taxa.