Brachyhypopomus bullocki Sullivan & Hopkins, 2009

Family:  Hypopomidae (Bluntnose knifefishes)
Max. size:  22.1 cm TL (male/unsexed)
Environment:  benthopelagic; freshwater
Distribution:  South America: Orinoco basin in Venezuela and Colombia; rio Branco drainage in Guyana and Brazil, as well as in the upper rio Negro near the mouth of the rio Branco, but is not known from elsewhere in the Amazon system, or in the Guianas.
Diagnosis:  Anal soft rays: 196-233. Can be distinguished by the following combination of features: elongated caudal filament reaching up to 45% TL in reproductive males; 6-11 wide, evenly spaced saddles of pigment over dorsum connecting to lateral bands; mesocoracoid bone present; large eye, 15.5-19.2% HL; short abdomen, usually with 12 pre-caudal vertebrae (range 11-13); poorly ossified third and fourth (outermost) branchiostegal rays, much enlarged distally, covering distal portions of the first two branchiostegal rays externally and contributing to bulbous appearance of opercular region (Ref. 81045).
Biology:  Inhabits clear, shallow, standing water in open savanna, or savanna mixed with stands of Mauritia palm. Collected in the vegetation along the banks of small pools fed by steams. Occurs inactive during the day among the stems and roots of emergent grasses and sedges. Encountered only in very low conductivity water (<25 μS/cm) where it usually co-inhabits with Brachyhypopomus brevirostris. The electric organ discharge waveform is biphasic, 0.9-1.6 milliseconds in duration, and the pulse rate ranges from 20 to 80 Hz (Ref. 81045).
IUCN Red List Status: Least Concern (LC); Date assessed: 27 August 2020 Ref. (130435)
Threat to humans:  harmless


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