Abstract
Color pattern is an important character in the systematics and alpha-taxonomy of electric fishes of the genus Gymnotus. This paper presents evidence of color variation in populations of G. pantanal found in the streams Jacutinga and Pinheirinho, in the upper Paraná River basin, southern Brazil. Color variations were corroborated for morphological and cytogenetic data. Our results show the importance of integrating morphologic and cytogenetic data in the taxonomy of the Gymnotus species.
Highlights
The genus Gymnotus Linnaeus comprises 35 valid species of electric fishes, including aggressive and nocturnal gymnotiform eels of shallow freshwaters distributed from southern Mexico to Argentina (Cognato et al, 2007; Maxime & Albert, 2009; Richer-de-Forges et al, 2009)
Fernandes et al (2005) used morphological, cytogenetic, and molecular data to describe that species; in their diagnosis color pattern was the main morphological trait: ‘Gymnotus pantanal differs from other members of the G. pantherinus Steindachner speciesgroup in possessing a color pattern composed of thin obliquely-oriented pale pigment bands with wavy margins restricted to the ventral portion of the body on the anterior half of the body’
Diploid numbers vary from 39-40 (G. pantanal) to 54 (G. paraguensis), and differences in karyotypic macrostructure were observed among the analyzed species
Summary
The genus Gymnotus Linnaeus comprises 35 valid species of electric fishes, including aggressive and nocturnal gymnotiform eels of shallow freshwaters distributed from southern Mexico to Argentina (Cognato et al, 2007; Maxime & Albert, 2009; Richer-de-Forges et al, 2009). Gymnotus pantanal was described by Fernandes et al (2005) in the Paraná-Paraguay system, in Brazil and Paraguay, and in the River Chapare-Mamoré, in Bolivia. Despite the high diversity of this genus, only eight species of Gymnotus have been cytogenetically analyzed: G. paraguensis Albert & Crampton, 2003, G. pantherinus (Steindachner, 1908), G. inaequilabiatus (Valenciennes, 1839) G. sylvius Albert & Fernandes-Matioli, 1999 (FernandesMatioli et al, 1998), G. pantanal Fernandes, Albert, DanielSilva, Lopes, Crampton & Almeida-Toledo, 2005 (Fernandes et al, 2005; Silva & Margarido, 2005), G. mamiraua Albert & Crampton, 2001 (Milhomem et al, 2007), Gymnotus sp. G. pantanal is the only species of the genus with a multiple sex chromosome system (Silva & Margarido, 2005)
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