New Gymnotus knifefish discovered in Uruguay


Scientists from the University of Louisiana and the University of Central Florida have described a new species of Gymnotus knifefish from Uruguay in the most recent issue of the journal Copeia.

Mathilde Richer-de-Forges, William Crampton, and James Albert name the new knifefish Gymnotus omarorum after Omar Macadar and Omar Trujillo-Cenoz, pioneers in the anatomical and physiological study of electrogenesis in Gymnotus.

Gymnotus omarorum is a member of the G. carapo species group, and differs from the members of this group in having a short distance to first ventral lateral-line ramus (39"45% total length), 27"35 pored scales to the first ventral ramus, 16"37 ventral lateral line rami, and ovoid scales on the posterior portion of the body.

The new species is known from the the Santa Lucia and Cisne river drainages of southeastern Uruguay and the Cuariem River drainage in northern Uruguay.

According to the authors, the new species lives in submerged stems and roots of aquatic vegetation in lakes and small streams.

The following water parameters were recorded at the type locality: electrical conductivity 170"190 S/cm, pH 7.6"7.8, temperature 23"28C. There is also some evidence that G. omarorum displays paternal brood care.

Gymnotus omarorum has been used for more than 30 years as a model organism in neurophysiological research (particularly by Uruguayan scientists), where it has been misidentified as G. carapo.

For more information, see the paper: Richer-de-Forges, MM, WGR Crampton and JS Albert (2009) A new species of Gymnotus (Gymnotiformes, Gymnotidae) from Uruguay: description of a model species in neurophysiological research. Copeia 2009, pp. 538"544.