A new species of electric knifefish has been described from southern Brazil.
The description of Gymnotus chimarrao by Diego Cognato, Mathilde Richer-de-Forges, James Albert and William Crampton is published in the latest issue of the journal Ichthyological Exploration of Freshwaters.
Gymnotus chimarrao can be distinguished from other members of the genus except for some large (more than 30 cm total length) specimens of G. ardilai in having an almost uniform olive green colour in which the oblique dark-pigmented bands are faint, and difficult to distinguish.
Gymnotus chimarrao further differs from G. ardilai in possessing a shallower body.
The new species is known only from the Tacquari River drainage in the southern Brazilian state of Rio Grande do Sul, and is named after the traditional mate tea (chimarro, Ilex paraguariensis) of Rio Grande do Sul State, Brazil, and neighboring countries in allusion to the similar uniform green colour.
The specimens were caught in a small stream (1.5 m wide) with a substrate of stream mud and sand.
According to the authors, all the specimens were captured ...from marginal grasses rooted to the bottom of the stream in areas sheltered from the stream flow (negligible current). Water was stained dark. Conductivity at capture site 107 Scm"1, temperature 24.1 C.
For more information, see the paper: Cognato, D, MM Richer-de-Forges, JS Albert and WGR Crampton (2007). Gymnotus chimarrao, a new species of electric fish (Gymnotiformes: Gymnotidae) from Southern Brazil. Ichthyological Exploration of Freshwaters 18, pp. 375"382.