Brachyhypopomus bennetti Sullivan, Zuanon & Cox Fernandes, 2013

Crampton, William G. R., Santana, Carlos D. de, Waddell, Joseph C. & Lovejoy, Nathan R., 2016, A taxonomic revision of the Neotropical electric fish genus Brachyhypopomus (Ostariophysi: Gymnotiformes: Hypopomidae), with descriptions of 15 new species, Neotropical Ichthyology (e 150146) 14 (4), pp. 639-790 : 681-685

Brachyhypopomus bennetti Sullivan, Zuanon & Cox Fernandes, 2013

( Figs. 1d , 13 ; Tables 2-5, 8)

Brachyhypopomus sp. 3 . - Crampton, 1996a: 77, table 6.1.a, species list; 79, fig. 6.1 inset 19-21, color photographs; 37, fig. 3.5; 85, fig. 6.2; 88, fig. 6.3; 92-94, figs. 6.4a, 6.5; 191, fig. 11.2; 193, fig. 11.3, EOD data; 110, table 7.5, 113, table 7.7, 115, fig. 7.1, habitats; 136, table 8.2a,b, diet; 151-160, figs. 9.2, 9.3, table 9.1a,b, hypoxia tolerance; 164-169, figs.10.1, 10.2, table 10.1, reproductive biology ( Brazil, central Amazon, ecology and signal diversity).

Brachyhypopomus bennetti . - Sullivan, 1997: 100 (description in unpublished thesis with disclaimer stating not available, a nomen nudum).

Brachyhypopomus sp. 2 . - Crampton, 1998a, 821, table 4, 834, fig. 9, drawing of adult specimen, with EOD; 837, fig. 10, drawing of caudal filaments of male and female ( Brazil, Amazonas, species and EOD diversity). - Crampton, 1998b, 314, table 2, list of Brachyhypopomus ( Brazil, Amazonas, hypoxia tolerance).

Brachyhypopomus sp. B . - Crampton, 1999, 17 ( Brazil, Amazonas, Mamirauá Reserve, listing of species). - Crampton & Albert, 2006, 672, fig. 23.8 inset 11, color photograph of head of live individual with EOD, position in phylogenetic tree; 681, notes on EODs (gymnotiform species and EOD diversity]. -Crampton et al., 2008, 231, fig. 6, black and white photograph of head of live individual ( Brazil, adaptations to hypoxia).

Brachyhypopomus sp. 1 . -Stoddard, 1999,255,fig.4, color photograph of live mature female specimen, with EOD (EOD evolution).

Brachyhypopomus sp. “benn”. -Crampton, 2011, 176, table 10.2, species list; 179, figs. 10.2-10.3, phylogeny, geographical and ecological distributions (gymnotiform biology).

Brachyhypopomus (Odontohypopomus) bennetti Sullivan et al., 2013 , 14, figs. 6-8, color photographs of holotype and paratypes, backlit electric organ, EODs (original description and assignment to subgenus Odontohypopomus , type locality – Brazil, Amazonas, nr. Manaus, Amazonas dr.). - Carvalho, 2013, 181- 185, figs. 41-43, position in phylogeny (phylogenetic systematics of Rhamphichthyoidea ). - Crampton et al., 2016: 1-66, table 1, 3-4, figs. 1-7, 9, 18-20 (phylogeny, biogeography and ecology of Brachyhypopomus ; Odontohypopomus not recognized).

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

Description. Head and body shape, and pigmentation illustrated in Figs.1d 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. Very sparse, almost unnoticeable depigmented epidermal canals found mainly in posterior third of body – as parallel wavy lines either side of lateral line. Epidermal canals absent from either side of mid-dorsal region, and absent on flank midway from lateral line to dorsal midline. Hypaxial electric organ very large. Six bilateral electrocyte columns at anal-fin terminus, and 5-6 columns midway between anal-fin terminus and tip of caudal filament in immature, mature female, and mature male specimens. Number of columns of electrocytes in mid-caudal filament sometimes continues to tip, or sometimes dwindles to 2-3 columns. Caudal filament short to moderate in length.

Coloration. ( Figs. 1d , 13 ). Background pale straw to tan. Dorsal region with irregular brown blotches which extend to irregular-edged and sometimes divided brown bands which extend towards lateral line. No pale mid-dorsal stripe extending from occiput to base of caudal filament. A series of brown blotches is usually present along lateral line. Flank ventral to lateral line and pterygiophore region with very sparse and indistinct disrupted vertical bands. Caudal filament darker than body, with indistinct dark blotches and disrupted vertical bands. Head darker, especially dorsally. Eye with prominent suborbital patch of chromatophores and subcutaneous pigmentation (sometimes indistinct). Pectoral and anal-fin membranes hyaline. Pectoral and anal-fin rays hyaline with light scattering of brown chromatophores. Anal-fin ray pigmentation darker in posterior half of fin. Color in live individuals similar to preserved specimens, body sometimes with yellow-green tinge in waters with high sediment load, opercular region usually very rosy due to underlying gills.

Size. Moderate adult size, largest specimen examined 235 mm TL, 215 mm LEA (n = 1,444). Largest male specimen examined 223 mm TL, 183 mm LEA (n = 51). Largest female specimen reported 215 mm TL, 176 mm LEA (holotype) (n = 89) .

Sexual dimorphism. Mature males in breeding condition attain slightly larger sizes, and develop much deeper caudal filaments than immature individuals and breeding females ( Figs. 13 b-c). Breeding males without an elevated number of bilateral horizontal columns or vertical rows of electrocytes. Instead breeding males exhibit clearly enlarged electrocytes relative to immature specimens and females. Breeding males with paddle-like lateral compression at caudal filament tip, which is partially or sometimes completely free of electrocytes. No known sexual dimorphism in pigmentation.

Geographic distribution. Bolivia, Brazil, Colombia, Ecuador, and Peru ( Fig. 14 ). Restricted to whitewater floodplains of the main stem of the Amazon River and the lower reaches of its major whitewater tributaries, and known also from a single specimen (CAS 81631) from the upper río Beni floodplain, well above the major series of falls on the rio Madeira. This specimen was collected in 1921 by Nathan E. Pearson during the Mulford Expedition, and although faded, exhibits the diagnostic six horizontal electrocyte columns at the anal-fin terminus. One of us (WGRC) made extensive collections in the lower río Beni, near Riberalta, Bolivia, but failed to locate other specimens of B. bennetti in this area.

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, 1996a; 1998a,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, 1998a). 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 floating macrophytes ( Crampton, 1996a: 165). Size class data from floodplain floating macrophytes indicate that B. bennetti has an annual life history; it reaches maturity and breeds within one year, and exhibits post-reproductive mortality ( Crampton, 1996a: 166, fig. 10.1). The species is also relatively common in rooted and floating macrophytes along the edge of major whitewater river channels. Brachyhypopomus bennetti is absent in blackwater and clearwater systems except very close to their confluences with major whitewater rivers (for example in lago Tefé, near its confluence with the rio Solimões), where there are frequent ingresses of high-conductivity water.

Brachyhypopomus bennetti is a high-conductivity specialist, and its electric organ exhibits impedance matching to systems with low resistance (high conductivity) – with many bilateral columns of electrocytes ( Crampton, 1998a; Crampton & Albert, 2006; Sullivan et al., 2013). Brachyhypopomus bennetti is also adapted to protracted periods of anoxia, by undertaking aerial gill respiration ( Crampton, 1996a; 1998b), and its gill lamellae are greatly expanded in comparison to species form normoxic systems, such as terra firme forest streams (Crampton et al., 2008). Brachyhypopomus bennetti reproduces during the late-rising and high water period ( Crampton, 1996a). Stomach contents in populations from the central Amazon comprise aquatic insect larvae, microcrustacea, and other small aquatic invertebrates – with a predominance of Chironomidae larvae ( Crampton, 1996a: 165).

Co-occurring congeners: Brachyhypopomus bennetti is known to co-occur in geographical sympatry and ecological syntopy with the whitewater floodplain-occurring species: B. beebei , B. belindae , B. brevirostris , B. flavipomus , B. hamiltoni , B. pinnicaudatus , B. regani , and B. walteri (and B. arrayae , and B. bombilla in the upper Madeira). It also exhibits an allotopic distribution with: B. batesi , B. benjamini ¸ B. hendersoni , B. sullivani , and B. verdii (and with B. alberti in the upper Madeira).

Local names. Brazil: sarapó; Colombia: cuchillo; Ecuador: cuchillo, yayo; Peru: macana.

Material examined. 1,466 specimens, localities from Amazonas dr. Bolivia. Beni. CAS 81631, 1, 142 mm (126 mm LEA), Reyes, pampa town, 24 mi. NE Rurrenabaque, río Beni, affl. rio Madeira, 14°17′42″S, 067°20′27″W. Note: Sullivan et al. (2013) mistakenly duplicated the record for CAS 81631 with CAS 72216 in the nontype list of the original description, CAS 81631 was in fact dismembered from CAS 72216. Brazil. Amazonas (localities listed from Mamirauá Reserve [ Reserva de Desenvolvimento Sustentável Mamirauá ] are in rio Solimões-Japurá floodplain, mun. Alvarães ). ANSP 194026, 4 , INPA 39562 , 5 , rio Camatiã , Monte Sinai, São Paulo de Olivença, 03°27′34″S, 068°56′00″W (listed by Sullivan et al., 2013) . BMNH 1998.3.12 56-62, 7, immature, INPA 18353 , 2 , immature, 51-85 mm , MCP 45252 , 1 , immature ( CS), 83 mm, Mamirauá Reserve, lago Juruazinho , 03º02′41″S, 064º51′26″W . BMNH 1998.3.12 63-64, 2, female, mun. Tefé, lago do Içé, Ilha do Içé, rio Solimões , 03°16′04″S, 064°41′29″W . BMNH 1998.3.12.67-74, 8, BMNH 1998.3.12.65, 1, male, 210 mm, BMNH 1998.3.12.66, 1, male, 192 mm, BMNH 1998.3.12.80, 1, male, 181 mm, BMNH 1998.3.12.81, 1, female, 154 mm, INPA 18352 , 1 , female, 139 mm , INPA 18356 , 1 , immature, 50 mm , MCP 33278 , 2 , 170-178 mm , MCP 45330 , 1 , male, 200 mm , MCP 45389 , 1 , female, 165 mm , MCP 46934 , 1 ( CS) 73 mm, Mamirauá Reserve, cano do lago Rato , 03º02′41″S, 064º51′26″W . BMNH 1998.3.12.75, 1, immature, 156 mm, BMNH 1998.3.12.76, 1, female, 151 mm, BMNH 1998.3.12.77, 1, male, 210 mm, BMNH 1998.3.12.78, 1, female, 152 mm, Mamirauá Reserve, Ressaca do Caetono , 02º50′15″S, 064º55′50″W . BMNH 1998.3.12.79, 1, female, 175 mm, Mamirauá Reserve, Ressaca do Pau , 03º02′03″S, 064º52′13″W . BMNH 1998.3.12.82, 1, immature, 90 mm, Mamirauá Reserve , lago Sumaumeirinha I, 02º48′26″S, 065º04′33″W . Rio Juruá nr. confl. with rio Solimões , CU 97640, 3 (paratypes), ca. 02°40′S, 065°45′W . IDSM 454, 3, 97-110 mm, Mamirauá Reserve, lago Secretaria , 03º07′12″S, 064°47′49″W . IDSM 455, 2, 81-83 mm, Mamirauá Reserve, lago Jaraqui , 02º44′07″S, 065°04′38″W . INHS 44485, 5, 110-199 mm, INHS 70542 (part), 5, MZUSP 75571 (part), 6, 106-155 mm , USNM 306929 , 6 , 71-162 mm , USNM 306947 , 1 , lago Camaleão, Ilha da Marchantaria, rio Solimões , 03°14′22″S, 059°56′37″W . INPA 6403 , 5 (1 measured, 118 mm), lago Janauacá, Ilha Janauacá, rio Amazonas , 03°24′S, 060°15′W . INPA 39560 , 1 (holotype), 215 mm, examined from photograph in Sullivan et al. (2013), Paraná do Paracuúba, nr. mouth of lago Janauari, rio Amazonas , 03°12′36″S, 059°59′24″W . INPA 8940 , 3 (paratypes), 1, 190 mm, examined from photograph in Sullivan et al. (2013) , INPA 39581 , 1 (paratype), 175 mm, examined from photograph in Sullivan et al. (2013), nr. lago Janauari, rio Amazonas , 03°12′36″S, 060°01′54″W . INPA 9944 , 40 , 52-175 mm, Mamirauá Reserve, lago Mamirauá , 03º07′S, 064º47′W . INPA 13569 , 2 , 45-67 mm, Ilha da Marchantaria, rio Solimões , 03°14′22″S, 059°56′37″W . INPA 15816 , 4 (2 female, 170 mm, 2 male, 160- 88 mm) , INPA 18243 , 1 , immature, 192 mm , INPA 18362 , 1 , female, 139 mm , MCP 33279 , 1, 176 mm , MCP 45253 , 2 (1 female, 179 mm, 1 male, 219 mm) , MCP 45255 , 8 (4 immature, 119-135 mm, 3 female, 116-145 mm, 1 male, 196 mm), Mamirauá Reserve, lago Secretaria , 03º07′12″S, 064°47′49″W . INPA 18241 , 1 , male, 221 mm , MCP 45251 , 2 (1 immature, 129 mm, 1 male, 216 mm), Mamirauá Reserve, cano do lago Sapucaia , 03º04′07″S, 064°48′32″W . INPA 18242 , 1 , male, 210 mm, Mamirauá Reserve, lago Periquito Redondo , 03º04′50″S, 064°46′35″W . INPA 18244 , 11 (6 female, 121-168 mm, 5 male, 173-223 mm) , MCP 45254 , 3 (1 female [CS], 141 mm, 2 male, 179-189 mm), Mamirauá Reserve, lago Geraldo , 03º06′53″S, 064°49′06″W . INPA 18245 , 4 (1 female, 152 mm, 3 male, 190-208 mm) , MCP 45392 , 2 (1 immature, 103 mm, 1 female, 170 mm), Mamirauá Reserve, lago Curuçá Aberto , 03º06′07″S, 064°49′10″W . INPA 18246 , 3 (2 female, 150-166 mm, 1 male, 203 mm) , MCP 33281 , 3 , 169-179 mm , MCP 45393 , 1 , male, 190 mm, Mamirauá Reserve, lago Curuçá Comprido , 03º05′31″S, 064°48′58″W . INPA 18348 , 1 , female, 145 mm , INPA 18349 , 1 , female, 162 mm , MCP 45345 , 10 (5 female, 160-170 mm, 5 male, 190-208 mm), Mamirauá Reserve, cano do lago Arauaé , 03º03′54″S, 064º49′04″W . INPA 18350 , 1 , female, 161 mm , MCP 45348 , 3 , female, 156-177 mm , MCP 45394 , 1 , immature, 132 mm, Mamirauá Reserve, lago Araçazinho , 02º59′35″S, 064º51′33″W . INPA 18351 , 2 (1 female, 139 mm, 1 male, 160mm) , MCP 45347 , 1 , female, 138 mm , MCP 45399 , 1 , male, 170 mm, Mamirauá Reserve, lago Periquito Comprido , 03º04′57″S, 064°46′42″W . INPA 18354 , 3 , immature, 46-102 mm , INPA uncat.$$ (ex. 18356), 1, immature, 41 mm, MCP 45346 , 3 , female (1 CS), 142-156 mm , MCP 45390 , 1 , immature, 107 mm , MCP 45391 , 1 , female, 110 mm, Mamirauá Reserve, lago Juruá Grande , 03º01′51″S, 064º51′07″W . INPA 18355 , 3 , female, 142- 162 mm , MCP 45401 , 1 , immature, 77 mm, Mamirauá Reserve, lago Promessa , 03º04′29″S, 064°47′02″W . INPA 18357 , 3 (1 immature, 45 mm, 1 female, 148 mm, 1 male, 206 mm) , MCP 33280 , 1 , 76 mm, Mamirauá Reserve , lago Curuçá Redondo, 03º06′13″S, 064°49′06″W . INPA 18358 , 2 (1 immature, 52 mm, 1 female, 156 mm), Mamirauá Reserve, lago Miratinin , 03º04′44″S, 064°50′17″W . INPA 18359 , 2 , immature, 50-59 mm , MCP 45256 , 1 , female, 165 mm, Mamirauá Reserve, cano do lago Mamirauá , 03º05′15″S, 064°48′03″W . INPA 18360 , 4 , immature, 42-55 mm , MCP 45257 , 2 , immature, 87-91 mm , MCP 45465 , 2 , female, 142- 178 mm, Mamirauá Reserve, Ressaca da Vila Alencar , 03º07′41″S, 064°48′04″W . INPA 18361 , 2 , immature, 54-63 mm , MCP 45429 , 1 , immature, 78 mm, Mamirauá Reserve, lago Apolônio , 03º07′03″S, 064°48′30″W . INPA 32091 , 3 , Lago do Rei, rio Amazonas floodplain, ca. 03º09′S, 059°41′W . INPA 33187 , 3 , Ressaca do Luizinho, rio Jutaí , 02º42′58″S, 066º48′13″W (listed by Sullivan et al., 2013) . INPA 33196 , 1 , Palmares, Tabatinga, rio Solimões , 03º57′53″S, 069°20′11″W (listed by Sullivan et al., 2013) . INPA 33255 , 3 , Ilha da Paciência, rio Solimões floodplain, 03º16′41″S, 060°16′35″W (listed by Sullivan et al., 2013) . INPA 33270 , 3 , Lago Ressaca Grande, Fonte Boa, 02º28′26″S, 063°09′17″W (listed by Sullivan et al., 2013) . INPA 39563 , 4 , Coari, 03º51′10″S, 063°28′07″W (listed by Sullivan et al., 2013) . MCP 45315 , 2 , female, 146-164 mm , MCP 45316 , 1 , male, 156 mm , MCP 45359 , 17 (13 female [2 CS], 140-175 mm, 4 male [1 CS], 164-206 mm), Mamirauá Reserve, lago Araçazinho , 02º59′35″S, 064º51′33″W . MCP 45384 , 4 (3 female, 157-162 mm, 1 male, 195 mm) , MCP 45388 , 1 , immature, 152 mm, Mamirauá Reserve, lago Arauaé , 03º02′52″S, 064º50′04″W . MCP 45400 , 1 , immature, 98 mm, Mamirauá Reserve, lago Tracajá , 03º05′43″S, 064°46′31″W . MCP 45451 , 1 , male, 196 mm, Mamirauá Reserve, Paraná Maiana , 03º06′50″S, 064°47′48″W . MCP 45466 , 1 , female, 136 mm , MCP 45467 , 4 , immature, 82-125 mm, mun. Tefé, floodplain lake, Ilha Panamim, rio Solimões , 03°19′06″S, 064°38′36″W . MCP 45471 , 2 , immature, 102-122 mm, mun. Tefé, lago Jacaré , 03°11′11″S, 064°43′05″W . MCP 47021 , 1 , female, 158 mm, Mamirauá Reserve, lago Pagão , 03º02′32″S, 064º50′25″W . MCZ 9354, 6, 80-95 mm, mun. Parintins, Villa Bella [Vila Bela], rio Amazonas at Parintins and environs, ca. 02°38′S, 056°45′W . MCZ 78163 (part), 7, 83-122, lago Jacaretinga, nr. Careiro de Várzea, rio Amazonas , 03°13′00″S, 059°49′41″W . MPEG 1111, 2, 103-151 mm, mun. Iranduba, rio Solimões, nr. Manaus , ca. 03°17′S, 060°11′W [coordinates for Iranduba]. MPEG 1123 (part), 7, 57-82, mun. Tefé, Costa Capivara, rio Solimões , ca. 03°16′38″S, 064°38′09″W . MPEG 22745, 8, 88-215 mm, Mamirauá Reserve, lago Mamirauá , 02º59′38″S, 064°54′26″W . MPEG 22746, 2, 96-131 mm, Mamirauá Reserve, lago Bolsinho , 03º03′47″S, 064°49′59″W . MZUSP 6326 (part), 1, 95 mm, lago Castro, Boca do rio Purus, rio Purus , 03°42′S, 061°28′W . MZUSP 78954 (part), 1, 120 mm, Costa do Anori, nr. mouth of rio Purus, rio Solimões , 03°46′S, 061°37′W . USNM 306841 , 1 , Paraná do lago Janauacá, rio Amazonas , ca. 03°22′S, 060°10′W . USNM 306859 , 1 , lago Terra Preta, lago do Janauari, rio Amazonas , ca. 03°13′S, 060°00′W . USNM 306875 , 1 , lago Janauari, nr. mouth, rio Amazonas , ca. 03°13′S, 060°00′W . Pará. INPA 39564 , 1 , mun. Almeirim, Paranaguara, rio Amazonas , 01°44′29″S, 053°10′15″W (listed by Sullivan et al., 2013) . MPEG 2403, 7, 101-143, MPEG 3722, 1, 109 mm, mun. igarapé-Açu, Pantanal do rio Livramento, nr. iron bridge [on hwy. PA-230], rio Jambu-Açu, affl. rio Marapanin ( Amazon estuary), 01°07′21″S, 047°41′28″W . MCP 49401 , 6 , mun. Curuá, Lago Preto, Ilha São Luiz, rio Amazonas, Amazonas dr., 02°06′22″S, 055°10′17″W . MPEG 7588, 1, 85 mm, MPEG 7597, 1, 59 mm, mun. Ponta de Pedras, Ilha de Marajó, Sitio Castanhal , rio Quiã-Paraná , affl. rio São José , affl. rio Marajó-Açu , affl. Baía do Guajará ( Amazon estuary), 01°29′09″S, 048°55′24″W . MPEG 12562, 3, 118-147 mm, mun. Peixe Boi, branch of rio Peixe Boi, affl. rio Maracanã, ( Amazon estuary), ca. 01°00′S, 047°23′W [coordinates for mouth of rio Peixe Boi ] . UF 238557 , 2 , 131-140 mm, mun. Santarém, Lago de Santana, Ilha Marimarituba, rio Amazonas , 02°11′13″S, 055°02′21″W . UF 238570 , 10 , 66-107 mm , UF 238575 , 1, 113 mm ; UF 238577 , 8 , 66-104 mm ; UF 238580 , 3 , 100-102 mm; mun. Santarém, lago Pajau, rio Amazonas, 02˚11’29″S, 054˚51’28″W. Colombia. Amazonas. FMNH 85363, 38, 50-162 mm, río Amazonas 2-3 mi. upstream Leticia, ca. 04°12′S, 069°57′W . UF 25560 , 1, 121 mm , UF 25561 , 1 , 66 mm, N shore río Amazonas, just upstream Leticia , 04°08′S, 070°01′W . UF 33843 , 1, 151 mm, pools on banks of río Amazonas at Leticia , ca. 04°12′S, 069°56′W . USNM 216870 , 1 , Leticia, río Amazonas , ca. 04°12′S, 069°56′W . Ecuador. Francisco de Orellana. FMNH 102276, 8, 60-128, Laguna Anangucocha , río Napo, 00°32′00″S, 076°26′42″W . Sucumbios. FMNH 102270, 2, 63-130, Laguna de Limoncocha , río Napo, 00°23′42″S, 076°36′49″W . QCAZ-I 1960, 1, 149 mm, QCAZ-I 1965 1, 176 mm, QCAZ-I 1968, 1, 138 mm, floodplain lake nr. Sacha Lodge , río Napo, 00°28′24″S, 076°27′24″W . Peru. Loreto. AMNH 78060, 14 (7 examined), 88- 119 mm, río Yarapá , affl. río Ucayali, 04°31′S, 073°22′W . ANSP 178397, 1, mouth of caño Chincana, río Yanayacu , 04°19′51″S, 073°18′01″W . INHS 36829, 3, 72-193 mm, caño Ushpa, affl. río Itaya, affl. río Amazonas , ca. 03°48′S, 073°16′W . INHS 39732, 1, 85 mm, INHS 43679, 9, 60-120 mm, INHS 52031, 3, 130-144 mm, INHS 53874, 3, 98-132 mm, caño Moena nr. confl. with caño Ullpa, affl. río Itaya , affl. ríoAmazonas, 03°46′20″S, 073°14′17″W . INHS 54795, 6, 49-125 mm, floodplain S Nauta, río Marañón , 04°30′36″S, 073°34′06″W . MCP 26186 , 29 , 35-166 mm , MCP 26196 , 8 , 58-98 mm, Reserva Nacional Pacaya Samiria ( RN Pacaya Samiria), río Pacaya , affl. río Ucayali, no coordinates . MCP 49413 , 3 , RN Samiria, Nauta Caño, affl. río Marañón , 04°39′33″S, 073°39′03″W . MUSM 4319 , 5 , 78-139 mm, quebrada Mondongo, río Huallaga, nr. Yurimaguas, affl. río Marañón , ca. 05°53′S, 076°04′W . MUSM 4499 , 4 , nr. Contamana, río Ucayali, 07°20′S, 075°01′W . MUSM 14498 (part), 1, 133 mm, Puesto de Vigiliancia Arcadia, río Napo , 00°59′37″S, 075°18′30″W . MUSM 17333 , 8 , MUSM 17341 , 22 , RN Pacaya Samiria, caño Yarina, Puesto de Vigilancia II , río Pacaya , affl. río Ucayali, 05°20′S, 074°30′W . MUSM 44757 , 1 , immature, 117 mm, cocha Supay, nr. Jenaro Herrera, río Ucayali floodplain, 04°55′16″S, 073°42′32″W . MUSM 44769 , 52 (42 immature, 34-131 mm, 7 female, 71-109 mm, 3 male, 115-192 mm), cocha Capite, nr. Jenaro Herrera , río Ucayali floodplain, 04°51′21″S, 073°40′24″W . NRM 13522 (part), 1, 101 mm, NRM 27700, 1, 86 mm, caño Sacarita, opposite Pebas, río Ampiyacu, affl. río Amazonas , ca. 03°19′S, 071°50′W . NRM 27523 (part), 1, 106 mm, lago Matamata, affl. caño, río Yavarí (rio Javari) upstream from Atalaia do Norte ( Brazil ), 04°12′S, 070°17′W . UF 114640 , 7 , 64-90 mm, RN Pacaya Samiria, río Pacaya , affl. río Ucayali, ca. 05°20′53″S, 074°30′18″W . UF 126151 , 10 , 60-150 mm , UF 126193 , 1 , 90 mm , UF 131416 , UF 129752 , 6 , 64-181 mm, 1, immature, 112 mm, RN Pacaya Samiria, caño Yarina , affl. río Ucayali, 05°20′09″S, 074°30′05″W . UF 126161 , 1, 116 mm , UF 129790 , 2 , 75-85 mm , UF 131417 , 1 , immature, 108 mm, RN Pacaya Samiria, cocha Sapote, río Pacaya , affl. río Ucayali, 05°19′06″S, 074°29′18″W . UF 126172 , 1, 110 mm , UF 128802 , 24 , 98-183 mm , UF 128870 , 13 , 95-175 mm , UF 128875 , 50 , 48-230 mm , UF 128876 , 39 , 62-155 mm , UF 128913 , 54 , 31-130 mm , UF 128915 , 35 , 55-165 mm , UF 128929 , 17 , 52- 200 mm , UF 128953 , 4 , 65-193 mm , UF 128955 , 26 , 65-185 mm , UF 128966 , 14 , 33-200 mm , UF 129099 , 37 , 61-175 mm , UF 129100 , 14 , 53-190 mm , UF 129122 , 4 , 65-120 mm , UF 129177 , 1, 160 mm , UF 129178 , 11 , 63-235 mm , UF 129230 , 33 , 68-170 mm , UF 129240 , 11 , 57-180 mm , UF 129245 , 22 , 60-190 mm , UF 129251 , 57 , 40-190 mm , UF 129273 , 62 , 37-175 mm , UF 129299 , 18 , 80-114 mm , UF 129325 , 15 , 97-176 mm , UF 129331 , 20 , 75- 140 mm , UF 129333 , 35 , 90-110 mm , UF 129335 , 59 , 45-160 mm , UF 129410 , 40 , 87-207 mm , UF 129814 , 4 , 35-110 mm , UF 131418 , 12 , 71-200 mm, RN Pacaya Samiria, río Pacaya , affl. río Ucayali, ca. 05°16′S, 074°27′W . UF 126301 , 2 , 74-87 mm , UF 129800 , 26 , 58-110 mm, RN Samiria, río Pacaya upstream caño Narina, affl. río Ucayali, 05°25′48″S, 074°30′19″W . UF 129456 , 42 , 45-145 mm, RN Pacaya Samiria, caño Tamara, affl. río Ucayali, 05°16′40″S, 074°29′38″W . UF 129458 , 1, 160 mm, RN Pacaya Samiria, cocha Yanayacu, río Pacaya , affl. río Ucayali, 05°18′14″S, 074°26′12″W . UF 129751 , 2 , 138-175 mm, RN Pacaya Samiria, río Pacaya , affl. río Ucayali, ca. 05°17′37″S, 074°29′53″W . UF 131421 , 1 , male, 190 mm, RN Pacaya Samiria, cañoYarina, río Pacaya , affl. río Ucayali, 05°18′16″S, 074°30′02″W . UMMZ 185108, 1, 115 mm, caño Moena, mouth of caño Ullpa, affl. río Itaya, affl. rio Amazonas , 03°46′19″S, 074°30′02″W . Ucayali. MCP 44238 , 2 , 87-92 mm, caño Cashibo, Yarinacocha, affl. río Ucayali, 08°17′08″S, 074°37′50″W . MUSM 1550 , 1, 143 mm , MUSM 1791 , 1, 117 mm, cocha Tacshitea, N Pucallpa, río Ucayali, 08°02′S, 074°39′W . MUSM 3586 , 3 (2 immature, 79-102 mm, 1 male, 118 mm) , MUSM 3606 , 7 (3 immature, 69-113 mm, 1 female, 139 mm, 3 male, 114-164 mm) , MUSM 3629 , 1, 128 mm, lago Imiria, Bella Flor, Coronel Portillo , affl. río Ucayali, 08°51′S, 074°16′W . MUSM 6245 , 15 (6 immature, 49-111 mm, 6 female, 111-166 mm, 3 male, 127-137 mm), Cashibococha, nr. Pucallpa , río Ucayali, 08°20′S, 074°39′W . MUSM 9285 , 1 , immature, 61 mm , MUSM 10874 , 3 (2 immature, 93-100 mm, 1 male, 159 mm), floodplain nr. Contamana , río Ucayali, 07°21′S, 075°00′W .

Figures

Fig. 1. Live individuals of 12 sympatric species of Brachyhypopomus and one species of Microsternarchus from the vicinity of Tefé, Amazonas, Brazil (Amazonas dr.). a. Brachyhypopomus batesi MCP 45312 (WC01.191293b), immature, 102 mm TL. b. Brachyhypopomus beebei head – uncat., immature, 75 mm TL; body – MCP 45450 (WC04.090600), female, 178 mm TL. c. Brachyhypopomus belindae MCP 45430, paratype, immature, 104 mm TL (photographed out of water, close up of head not available). d. Brachyhypopomus bennetti MCP 45451, male, 196 mm TL. e. Brachyhypopomus brevirostris uncat., immature, 224 mm TL. f. Brachyhypopomus flavipomus MCP 45453 (WC09.090600), female, 98 mm TL. g. Brachyhypopomus hamiltoni MCP 45482 (WC05.080301), holotype, female, 97 mm TL. h. Brachyhypopomus hendersoni MCP 45489, female, 164 mm TL. i. Brachyhypopomus pinnicaudatus MCP 45455, female, 135 mm TL. j. Brachyhypopomus regani, MCP 45285 (WC02.100301), male, 119 mm TL. k. Brachyhypopomus sullivani MCP 45464 (WC04.210201), immature, 79 mm TL. l. Brachyhypopomus walteri MCP 45458 (WC 03.090600), male, 161 mm TL. m. Microsternarchus bilineatus uncat., 85 mm TL.

Fig. 13. Brachyhypopomus bennetti. a. MCP 47021 (WC13.160893), female, 158 mm TL (head in lateral view, and body in lateral and dorsal views, specimen fixed in formalin and preserved in EtOH). b. MCP 45359 (WC18.050497), male, 192 mm TL (body in lateral view, specimen fixed in formalin and preserved in EtOH). c. MCP 45359 (WC12.050497), female, 169 mm TL (body in lateral view, specimen fixed in formalin and preserved in EtOH); Brazil, rio Solimões-Japurá confluence, Amazonas dr. Note the sexual dimorphism in caudal filament height. Scale bars = 5 mm.

Fig. 14. Collection records for Brachyhypopomus bennetti (circles), B. cunia (squares), and B. diazi (triangles). Holotype locations for B. bennetti and B. cunia, and location of lost holotype for B. diazi are marked with open symbols. Elevation data refers to altitude above mean sea level (see Fig. 2 for legend).