Brachyhypopomus bombilla
Loureiro M. & Silva A. A New Species of Brachyhypopomus (Gymnotiformes, Hypopomidae) from Northeast Uruguay. Copeia 2006, nimber 4
ABSTRACT
A new species of Brachyhypopomus from north and northeast Uruguay is described. The new species is found in tributaries of the Uruguay River and southern Los Patos-Merín system. Brachyhypopomus bombilla can be distinguished from all other species of the genus by the following combination of characters: pigmentation pattern of body consisting of scattered dark brown pigmentation over a brown background, more dense on the dorsal half of the body, epidermal laterosensory canals not depigmented, head depth 61.8–76.4% of HL, caudal filament 6.5–16.6% of TL, anal-fin rays 155–190, fourth supraorbital pore dorsal and halfway between posterior nares and anterior margin of orbit, upper jaw slightly longer than lower jaw, mesocoracoid bone not ossified, maxilla anterodorsal process slender, all branchiostegal rays of equal size, none hook-like. Like many other species of the genus Brachyhypopomus, B. bombilla generates a pulse-type biphasic EOD, with a head-positive phase followed by a head-negative phase. The EOD duration of the new species was significantly lower than the EOD duration of the sympatric B. pinnicaudatus, whereas the EOD rate was significantly higher, thus suggesting that duration and frequency are conspicuous electrophysiological parameters that greatly aid in the description of electric fish species.