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10 October 2011 A New Species of Gymnorhamphichthys (Gymnotiformes: Rhamphichthyidae) from the Paraná–Paraguay Basin
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Abstract

Gymnorhamphichthys britskii, new species, is described from the Paraná–Paraguay system. The new species is distinguished from all other congeners except G. hypostomus in having 5–16 (usually 9–13) large dark saddle-shaped pigment bars over the dorsal midline, extending between the nape and a vertical with the end of the anal fin, and sometimes reaching to or slightly below the lateral line. The new species differs from G. hypostomus in having 141–172 vs. 178–211 anal-fin rays; a shorter snout, preorbital distance 48.1–60.3% of head length (mean 54.6%) vs. 58.3–68.6% (mean 63.9%); a larger eye, diameter 5.7–9.0% of head length (mean 7.0%) vs. 3.3–5.9% (mean 4.3%); a longer distance from tip of snout to posterior nares, 17.1–22.0% of head length (mean 19.2%) vs. 11.2–17.1% (mean 13.8%); 7 vs. 9–13 displaced hemal spines; and 64–69 vs. 71–75 vertebrae to end of anal fin.

Gymnorhamphichthys britskii, nova espécie, é descrita para o sistema Paraná–Paraguai. A nova espécie se diferencia das demais de Gymnorhamphichthys, exceto G. hypostomus pela presença de 5–16 (usualmente 9–13) manchas negras dorsais alcançando ou ultrapassando a linha lateral, entre a nuca e a vertical do final da nadadeira anal. A nova espécie se diferencia de G. hypostomus pela presença de 141–172 raios na nadadeira anal vs. 178–211; por um menor focinho, comprimento preorbital 48.1–60.3% do comprimento da cabeça (média 54.6%) vs. 58.3–68.6% (média 63.9%); por um maior diâmetro do olho, 5.7–9.0% do comprimento da cabeça (média 7.0%) vs. 3.3–5.9% do comprimento da cabeça (média 4.3%); por uma maior distância do focinho até as narinas posteriores 17.1–22.0% (média 19.2%) vs. 11.2–17.1% do comprimento da cabeça (média 13.8%); pelo número de espinhos hemais deslocados, 7 vs. 9–13 e pelo número de vértebras até o final da nadadeira anal, 64–69 vs. 71–75 em G. hypostomus.

2011 by the American Society of Ichthyologists and Herpetologists
Tiago P. Carvalho, Cristiane S. Ramos, and James S. Albert "A New Species of Gymnorhamphichthys (Gymnotiformes: Rhamphichthyidae) from the Paraná–Paraguay Basin," Copeia 2011(3), 400-406, (10 October 2011). https://doi.org/10.1643/CI-10-154
Received: 28 September 2010; Accepted: 1 April 2011; Published: 10 October 2011
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