New knifefishes found in Amazon

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Two new species of knifefish have been found in the Amazon basin in Brazil.

The two fishes, which are members of the Ghost knifefish family Apteronotidae, have been placed in the genus Sternarchorhynchus and were discovered in Roraima state in Brazil.

Carlos de Santana and Adilia Nogueira, who described the new species in the journal Ichthyological Exploration of Freshwaters, named the species as Sternarchorhynchus severii and Sternarchorhynchus caboclo.

Both of the new Ghost knifefishes were caught near waterfalls and rapids on at Cachoeira on the Rio Mucajai, which flows into the Rio Amazonas.

The two species can be told apart from the other Sternarchorhynchus by both colouration and morphomeristic features.

Nogueira and de Santana wrote in their paper: "Sternarchorhynchus severii new species, is diagnosed from all congeners on the basis of body coloration, meristics and morphological characters such as white or yellow pigments along head and mid-dorsum forming long pale stripe, number of total anal-fin rays, and body proportion.

"Sternarchorhynchus caboclo, new species, is distinguished from the other species by the hyoid arch with four branchiostegal rays and the posttemporal not fused with the supracleithrum."

There are currently six others in the genus: S. britskii, S. curvirostris, S. mesensis, S. mormyrus, S. oxyrhynchus, and S. roseni.

For more details on the new species see the paper: de Santana CD and Adilia N (2006) - Two new species of Sternarchorhynchus Castelnau from the Amazon Basin, Brazil (Gymnotiformes: Apteronotidae). Ichthyol. Explor. Freshwaters, Vol. 17, No. 1, pp. 85-92, 4 fi gs., 1 tab., March 2006.