Brachyhypopomus bennetti

distribution

Distribution: Widely distributed in Amazon River Basin, in whitewater floodplains (Sullivan et al., 2013; Crampton et al., 2016 b).

Checklist of Gymnotiformes (Osteichthyes: Ostariophysi) and catalogue of primary types

biology_ecology

Ecological notes. Brachyhypopomus bennetti is exceptionally common (usually the most common gymnotiform) in floating rafts of macrophytes in whitewater floodplains along the main stem of the Amazon, and the lower reaches of its major whitewater tributaries (Crampton, 1996 a; 1998 a, b; 1999; 2011; Crampton & Albert, 2006; Crampton & Ribeiro, 2013; Sullivan et al., 2013). Water parameters for a typical central Amazon whitewater floodplain fluctuate within the following ranges through the annual flood cycle: conductivity 54 - 192 μScm- 1 dissolved oxygen 0 - 6.3 mgl- 1, temperature 26.5 - 34.0 ° C, and pH 6.3 - 7.3 (Crampton, 1998 a). During the low water period B. bennetti is found in floating macrophytes along the edges of floodplain channels or lakes, or in smaller pockets of water in low-lying areas of the floodplain. During the rising water period it is common both in floating macrophytes, and in submerged forest leaf-litter at the margin of the advancing flood waters. During the high water period, when the bottom waters are completely deoxygenated, B. bennetti is almost completely restricted to floating macrophytes. Reproduction occurs during the rising and high water period in

A taxonomic revision of the Neotropical electric fish genus Brachyhypopomus (Ostariophysi: Gymnotiformes: Hypopomidae), with descriptions of 15 new species

description

Description. Head and body shape, and pigmentation illustrated in Figs. 1 d and 13. Meristic and morphometric data for examined specimens presented in Tables 2 - 5 and 8. Body moderate to broad in depth. Head moderate to long in length and shallow to moderate in depth. Dorsal profile of head approximately straight from occiput to snout, ventral profile of head approximately straight between operculum and snout, snout rounded. Eye moderate in size. Upper jaw with moderate sigmoidal angle between premaxillary and maxillary portions in lateral view. No accessory electric organ over operculum. Gill filaments on first gill arch 40 - 51 (median 46, n = 6). Pectoral fin moderate to broad in width, pectoral-fin rays 14 - 17 (mode 16). Precaudal vertebrae 17 - 19 (mode 18), including 1 - 2 (mode 2) transitional vertebrae. Anal-fin origin substantially (0.25 - 0.33 HL distance) anterior to tip of pectoral fin, never posterior. Anal-fin rays 218 - 250 (218 - 240, median 231 in population from central Amazon). Dorsal rami of recurrent branch of anterior lateral line nerve usually visible. Middorsal region of body scaled. Rows of scales above lateral line 5 - 7 (mode 6). Lateral line continuous

A taxonomic revision of the Neotropical electric fish genus Brachyhypopomus (Ostariophysi: Gymnotiformes: Hypopomidae), with descriptions of 15 new species

diagnosis

Diagnosis. Brachyhypopomus bennetti is diagnosed by: bilateral columns of electrocytes at the anal-fin terminus 6, vs. 3 - 5 in all congeners.

A taxonomic revision of the Neotropical electric fish genus Brachyhypopomus (Ostariophysi: Gymnotiformes: Hypopomidae), with descriptions of 15 new species