Thursday, September 26, 2013

New electric fish

Akawaio penak (Maldonado-Ocampo,
López-Fernández, Taphorn, Bernard, Crampton & Lovejoy 2013
The bluntnose knifefishes (family hypopomidae) are known from freshwater in Panama and South America. They are so called electric fishes which are known to produce electrical fields from a specialized structure called the electric organ. The electric organ consists of modified muscle or nerve cells, which became specialized for producing bioelectric fields far stronger than those that normal nerve or muscle cells generate. By using this organ the fishes are capable to create a single electrical output which is called electric organ discharge (EOD). Some species can emit an EOD powerful enough to stun prey. The amplitude of the signal can range from 10 to 600 Volts with a current of up to 1 Ampere. However, most electric fish usually generate a discharge that is less than one volt in amplitude. These are too weak to stun prey and instead are used for navigation, object detection and communication with other electric fish that have specific capabilities to detect EOD's. The bluntnose knifefishes belong to the group of weakly electric fishes. 

During a recent expedition to Guyana led by Hernán López-Fernández from the Royal Ontario Museum researchers discovered a new species of bluntnose knifefish. Akawaio penak, was discovered in the shallow, murky waters of the upper Mazaruni River in northern Guyana. The upper Mazaruni River is a hotspot for biological diversity, yet remains largely unexplored because of its remote location. The area contains countless rivers on top of a series of uplands that have remained isolated from the rest of South America for more than 30 million years. 

In their paper the researchers describe the specimens not only as a new species but also as a new genus based on characters of external morphology. The phylogenetic affinities of the new genus were inferred using data from one nuclear (rag2) and two mitochondrial (COI and cyt b) genes. 

Akawaio penak has a long organ running along the base of the body that produces the electric field. The electric field is used to navigate and to communicate with other members of the species. This trait is advantageous given the murky habitats of the habitat. The species is named in honour of the Akawaio Amerindians that populate the upper Mazaruni. The region is increasingly suffering from freshwater habitat degradation as a consequence of gold-mining in the area.

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