Brachypopomus gauderio is not the only electric knifefish recently described from South America, U.S. researchers John P. Sullivan* and Carl D. Hopkins** have described another member of the genus Brachyhypopomus and given it the name Brachyhypopomus bullocki.

This new species is named in honour of Theodore Holmes Bullock, a renowned neurobiologist who died in 2005. Bullock was a pioneer of the comparative neurobiology of both invertebrates and vertebrates and is credited with the first physiological recordings from an electroreceptor and for championing electric fishes as a model system in neurobiology. The electric organ discharge waveform of Brachyhypopomus bullocki is biphasic, 0.9–1.6 milliseconds in duration, and the pulse rate varies from 20–80 Hz.

Brachyhypopomus bullocki is found throughout the Orinoco Basin in Venezuela and
Colombia. It can also be encountered in the in the Rio Branco drainage of Guyana and the Roraima State of Brazil, as well as in the upper part of Rio Negro near the mouth of Rio Branco.

Brachyhypopomus bullocki appears to prefer clear, shallow, standing water in open savannah, or savannah mixed with stands of Mauritia palm. It has also been collected among plants growing along the banks of small pools fed by streams. In Rio Negro, a specimen was found amongst palm leaf litter near the outlet of a black water stream.

Brachyhypopomus bullocki distinguishes itself from its close relatives by having larger eyes (comparative to the head), a short abdomen, and distally enlarged poorly ossified third and fourth branchiostegal rays.

The paper can be downloaded from Cornell University.

* John P. Sullivan, Department of Ichthyology, The Academy of Natural Sciences, Philadelphia. Email: sullivan@ansp.org

** Carl D. Hopkins, Department of Neurobiology and Behavior, Cornell University, New York. Email: cdh8@cornell.edu

A new species of ghost knifefish has been described by ichthyologists James Albert and William Crampton. It has been given the name Compsaraia samueli in honour of Samuel Albert who presented the scientists with the type specimens.

Ghost knifefish (family Apteronotidae) are famous for their body shape and for using a high frequency tone-type electric organ discharge (EOD) to communicate. The native home of these fishes are South and Central America. Within the aquarium hobby, the Black ghost knifefish (Apteronotus albifrons) and Brown ghost knifefish (Apteronotus leptorhynchus) are fairly common.

Samuel’s ghost knifefish lives in the western Amazon of Peru and Brazil and was collected from flooded beaches and deep river channels. It can be distinguished from its close relatives by having a higher number of caudal-fin rays and a less tapering body shape in lateral profile.

Other distinctive features are the relatively short caudal peduncle and the comparatively small body size (as an adult). The mature male sports an extremely slender and elongated snout and engages in sparring with repeated aggressive non-contact postures, usually followed by jaw-locking and biting.

If you wish to learn more about Samuel’s ghost knifefish, see the paper: Albert, JS and WGR Crampton (2009) A new species of electric knifefish, genus Compsaraia (Gymnotiformes: Apteronotidae) from the Amazon River, with extreme sexual dimorphism in snout and jaw length. Systematics and Biodiversity[1] 7, pp. 81–92.

Genus: Compsaraia

New species: Compsaraia samueli