Unexpected species diversity in electric eels with a description of the strongest living bioelectricity generator

Is there only one electric eel species? For two and a half centuries since its description by Linnaeus, Electrophorus electricus has captivated humankind by its capacity to generate strong electric discharges. Despite the importance of Electrophorus in multiple fields of science, the possibility of additional species-level diversity in the genus, which could also reveal a hidden variety of substances and bioelectrogenic functions, has hitherto not been explored. Here, based on overwhelming patterns of genetic, morphological, and ecological data, we reject the hypothesis of a single species broadly distributed throughout Greater Amazonia. Our analyses readily identify three major lineages that diverged during the Miocene and Pliocene—two of which warrant recognition as new species. For one of the new species, we recorded a discharge of 860 V, well above 650 V previously cited for Electrophorus, making it the strongest living bioelectricity generator. © 2019, The Author(s)

Sternarchorhynchus curumim (Gymnotiformes: Apteronotidae), a new species of tube-snouted ghost electric knifefish from the low-land Amazon basin, Brazil

Sternarchorhynchus curumim, a new species of tube-snouted ghost knifefish, is described from the main river channel of the Rio Tefé, in the lowland Amazon basin of Brazil. This species is diagnosed from congeners on the basis of body and fin pigmentation, meristic characters such as number of scales above the lateral line at mid-body, and morphometric characters such as relative body proportions. We also provide notes on the ecology and electric organ discharges of this species. Copyright © 2006 Magnolia Press

A review of the South American electric fish genus porotergus (Gymnotiformes: Apteronotidae) with the description of a new species

The species currently assigned to the South American electric fish genus Porotergus are reviewed. Porotergus duende, a new species, is described from the lowland western Amazon basin in Brazil and Peru. Porotergus gimbeli from the lowland Amazon basin in Brazil and Peru, and P. gymnotus from the Essequibo drainage of Guyana are redescribed. Porotergus duende and P. gimbeli are restricted to deep channel habitats. Porotergus gymnotus occurs in shallow rivers. Notes on the ecology and electric organ discharge of P. duende and P. gimbeli are presented. A key to the members of the genus is provided. © 2010 by the American Society of Ichthyologists and Herpetologists

Sternarchorhynchus curumim (Gymnotiformes: Apteronotidae), a new species of tube-snouted ghost electric knifefish from the low-land Amazon basin, Brazil

Sternarchorhynchus curumim, a new species of tube-snouted ghost knifefish, is described from the main river channel of the Rio Tefé, in the lowland Amazon basin of Brazil. This species is diagnosed from congeners on the basis of body and fin pigmentation, meristic characters such as number of scales above the lateral line at mid-body, and morphometric characters such as relative body proportions. We also provide notes on the ecology and electric organ discharges of this species. Copyright © 2006 Magnolia Press

Chromosomal And Electric Signal Diversity In Three Sympatric Electric Knifefish Species (Gymnotus, Gymnotidae) From The Central Amazon Floodplain

This article examines recent government reforms in China to identify changes and lessons of the Chinese reform experience. The article provides a review of major government reform concepts and analyzes eight Chinese reform cases in four areas of government: personnel, structure, strategy, and process. These reforms have expanded the objectives and scopes of the past administrative reforms to include new governance concepts of promoting managerial competency, organizational capacity, accountability and transparency, and citizen participation. The reforms have not only reported positive lessons of local innovation and international connection but have also identified limitations and concerns about social and political stability. Implications about reform findings and challenges are provided for future studies of Chinese government reforms. © 2012 SAGE Publications

Differences In Karyotype Between Two Sympatric Species Of Gymnotus (Gymnotiformes: Gymnotidae) From The Eastern Amazon Of Brazil

In this paper we describe the karyotypes of two sympatric species of Gymnotus from Marajó Island, Pará, in the Eastern Amazon basin of Brazil. One of these species, G. mamiraua, has not previously been identified from this area. Karyotype studies demonstrate that G. cf. carapo Linnaeus, has 2n=42 (30M/SM+12ST/A) and G. mamiraua Albert & Crampton, 2n=54 (50M/SM+4ST). The Nucleolar Organizer Region (NOR) was found in the distal region of the short arm of pair 20 in G. cf. carapo and in the interstitial region of pair 1 of G. mamiraua. Both species have centromeric constitutive heterochromatin (CH) in all chromosomes and some in interstitial or distal regions. In both species, 4′6-Diamidino-2-phenylindole (DAPI) staining has shown banding concordant with C-banding, whereas the Chromomycin A3 (CMA3) staining in both species agrees with the NOR location. The new data and review of cytogenetic data in Gymnotus presented here is concordant with a hypothesis that G. carapo is either a complex of populations, or a complex of morphologically similar cryptic species with distinct karyotypes. These taxa may be reproductively isolated by prezygotic reproductive isolation barriers (such as the structure of the Electric Organ Discharge), or by post-zygotic barriers (such as karyotypic formula). The understanding of the cytogenetic structure of G. carapo, combined with associated studies of signal diversity, will yield insight into the mechanisms underlying the origins and maintenance of high species diversity in Gymnotus. Copyright © 2007 Magnolia Press

Differences in karyotype between two sympatric species of Gymnotus (Gymnotiformes: Gymnotidae) from the eastern amazon of Brazil

In this paper we describe the karyotypes of two sympatric species of Gymnotus from Marajó Island, Pará, in the Eastern Amazon basin of Brazil. One of these species, G. mamiraua, has not previously been identified from this area. Karyotype studies demonstrate that G. cf. carapo Linnaeus, has 2n=42 (30M/SM+12ST/A) and G. mamiraua Albert & Crampton, 2n=54 (50M/SM+4ST). The Nucleolar Organizer Region (NOR) was found in the distal region of the short arm of pair 20 in G. cf. carapo and in the interstitial region of pair 1 of G. mamiraua. Both species have centromeric constitutive heterochromatin (CH) in all chromosomes and some in interstitial or distal regions. In both species, 4′6-Diamidino-2-phenylindole (DAPI) staining has shown banding concordant with C-banding, whereas the Chromomycin A3 (CMA3) staining in both species agrees with the NOR location. The new data and review of cytogenetic data in Gymnotus presented here is concordant with a hypothesis that G. carapo is either a complex of populations, or a complex of morphologically similar cryptic species with distinct karyotypes. These taxa may be reproductively isolated by prezygotic reproductive isolation barriers (such as the structure of the Electric Organ Discharge), or by post-zygotic barriers (such as karyotypic formula). The understanding of the cytogenetic structure of G. carapo, combined with associated studies of signal diversity, will yield insight into the mechanisms underlying the origins and maintenance of high species diversity in Gymnotus. Copyright © 2007 Magnolia Press