Brachyhypopomus walteri 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 : 775-779

Brachyhypopomus walteri Sullivan, Zuanon & Cox Fernandes, 2013

( Figs. 1l , 46 ; Tables 2-5, 21)

Brachyhypopomus sp. 4 . - Crampton, 1996a: 77, table 6.1.a, species list; 79, fig. 6.1 inset 22-24, color photographs; 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; 165-169, table 10.1 reproductive biology ( Brazil, central Amazon, ecology and signal diversity).

Brachyhypopomus walteri . - Sullivan, 1997: 105 (description in unpublished thesis with disclaimer stating that nomenclatural acts not available, a nomen nudum).

Brachyhypopomus sp. 3 . - Crampton, 1998a: 821, table 4, 834, fig. 9, illustration of specimen, with EOD ( Brazil, Amazonas, species and EOD diversity). - Crampton, 1998b: 314, table 2, list of Brachyhypopomus ( Brazil, Amazonas, hypoxia tolerance).

Brachyhypopomus sp. C . - 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).

Brachyhypopomus sp. 2 . -Stoddard, 1999: 255, fig. 4, color photograph of live mature female specimen, with EOD (EOD evolution).

Brachyhypopomus sp. “walteri ”. -Stoddard et al., 1999: 610, fig. 1, black and white photograph of female specimen, with EOD (EOD evolution).

Brachyhypopomus sp. 2 . - Ferreira et al., 2007: 164, center right and bottom right photographs, live individuals, ( Brazil, Roraima, rio Branco, photographic album of fishes).

Brachyhypopomus sp. ‘wal’. -Crampton, 2011: 176, table 10.2, species list; 179, figs. 10.2-10.3, phylogeny, geographical and ecological distributions (gymnotiform biology).

Brachyhypopomus sp. 4 . -de Queiroz et al., 2013: 545, table 1, ( Brazil, rio Madeira, lago Cuniã, listing of fish species]. -Crampton & Ribeiro, 2013: 242, color photograph ( Brazil, rio Madeira, listing of hypopomids).

Brachyhypopomus (Odontohypopomus) walteri Sullivan et al., 2013: 8 , figs. 3-4, 8, color photographs of holotype, paratypes, backlit electric organs (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, 12, 18-20 (phylogeny, biogeography and ecology of Brachyhypopomus ; Odontohypopomus not recognized).

Diagnosis. Brachyhypopomus walteri is diagnosed from congeners by the following combination of characters: caudal filament length 27.8-56.4% LEA, vs. 7.4-26.8% in B. batesi , B. belindae , B. bennetti , B. palenque , B. provenzanoi , B. regani , and B. verdii ; distinct dark suborbital stripe present, vs. absent in B. alberti , B. arrayae , B. beebei , B. benjamini , B. brevirostris , B. bullocki , B. diazi , B. draco , B. flavipomus , B. gauderio , B. janeiroensis , B. jureiae , B. menezesi , B. occidentalis , and B. pinnicaudatus ; accessory electric organ over the opercular region absent, vs. present in B. bombilla ; absence of scattered conspicuous black or charcoal flecks on flanks, vs. presence in B. cunia , B. hendersoni , and B. sullivani .

Description. Head and body shape, and pigmentation illustrated in Figs. 1l and 46 . Meristic and morphometric data for examined specimens presented in Tables 2-5 and 21. Body shallow to moderate in depth. Head short to moderate in length and shallow to moderate in depth. Dorsal profile of head approximately straight from occiput to snout, ventral profile of head gently convex 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 34- 48 (median 39, n = 29). Pectoral fin moderate to broad in width, pectoral-fin rays 12-17 (mode of 15 in populations from the region of the type localities in the central Amazon basin; 14 in populations from the Paraguay basin). Precaudal vertebrae 16-20 (mode of 18 in populations from the region of the type localities in the central Amazon basin, and from the Paraguay basin), including 1-2 transitional vertebrae. Anal-fin origin substantially (0.25-0.33 HL distance) anterior to tip of pectoral fin, never posterior. Anal-fin rays 192-235 (median of 210 in populations from the region of the type localities in the central Amazon basin; 226 in populations from the Paraguay basin). 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 7). Lateral line continuous. Depigmented epidermal canals very sparse, almost unnoticeable, found mainly in middle section of body – as curved short lines (usually no more than one) 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. 3-4 bilateral columns at anal-fin terminus and at mid-point between anal-fin terminus and tip of caudal filament in immature, mature female, and mature male specimens. Three or four electrocyte columns sometimes alternate in middle of caudal filament. Caudal filament moderate in length to long.

Coloration. ( Figs. 1l , 46 ). Pigmentation strongly resembles that of B. bennetti . 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, often with darkened tip; darkened tip of caudal filament resembles root tips of water hyacinths when viewed underwater. Head darker, especially dorsally. Eye with prominent suborbital patch of chromatophores and subcutaneous pigmentation (rarely indistinct, never absent). Pectoralandanal-finmembraneshyaline. Pectoralandanal-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. A Brachyhypopomus of moderate adult size, largest specimen examined 215 mm TL, ca. 150 mm LEA (n = 1,400). Largest male specimen examined 195 mm TL, 136 mm LEA (n = 25). Largest female specimen examined 201 mm TL, 140 mm LEA (n = 55).

Sexual dimorphism. No salient sexual dimorphism in size. Breeding males develop elongated caudal filaments in comparison to immature individuals and breeding females

( Fig. 46a,b ), but do not exhibit an elevated number of horizontal bilateral columns or vertical rows of electrocytes. Instead breeding males exhibit clearly enlarged electrocytes relative to immature specimens and females. Tip of caudal filament in large males never exhibits a paddle-like lateral compression. No sexual differences in pigmentation.

Geographic distribution. Bolivia, Brazil, Ecuador, Guyana, Paraguay, and Peru ( Fig. 47 ). Widely distributed through the Amazon basin, including whitewater, clearwater and blackwater systems. Also known from the middle Essequibo, and from the Paraguay-Paraná drainage. Records from the Paraná-drainage are mostly from collections in the Pantanal Matogrossense in the northern río Paraguay, but a single specimen was collected from the río Paraná of Paraguay, at a latitude of 27°17′03″S. Sullivan et al. (2013) did not report B. walteri from the Paraná-Paraguay drainage .

Population variation: We found overlap in the range of meristic counts( Tables 2-5) and morphometric measurements ( Table 21), and observed similar pigmentation among populations of B. walteri from the central Amazon and from the upper Paraguay. These observations, in combination with molecular data ( Crampton et al., 2016), support the hypothesis that all populations we have assigned to B. walteri are members of a single geographically widespread species, which is morphologically and genetically distinct from all congeners.

Ecological notes. Brachyhypopomus walteri is an ecologically cosmopolitan species that occurs in both high-conductivity and low-conductivity systems, but is usually more abundant in low-conductivity systems. It is a common component of floating meadow habitats in the high-conductivity whitewater floodplains of the Amazon River and its whitewater tributaries, and also along the margins of low-conductivity blackwater rivers such as the rio Negro, and rio Tefé. In the central and upper Amazon, in the vicinity of Tefé, Brazil, and Iquitos, Peru, B. walteri is much more common in floating meadow communities of normoxic low-conductivity blackwater systems than in seasonally hypoxic high-conductivity whitewater systems. Populations from central Amazon whitewater floodplains are able to tolerate protracted periods of experimentally induced hypoxia by undertaking aerial gill respiration ( Crampton, 1998b). Brachyhypopomus walteri is also abundant in small low-conductivity terra firme rivers and streams, where it is associated with aquatic vegetation and submerged root masses and leaf litter. Sullivan et al. (2013) infer, incorrectly, that B. walteri is predominantly a white-water floodplain specialist that occurs in blackwater systems only near their confluence with whitewater systems. For instance, contrary to Sullivan et al. (2013), B. walteri is known from the rio Negro far from its confluence with the Amazon River near Manaus ( Fig. 47 ). Breeding occurs during the rising and high water period in populations from Amazonian floodplain floating macrophytes ( Crampton, 1996a: 165). 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: 136).

Co-occurring congeners: Because of its wide geographical range and occurrence in multiple habitats, B. walteri occurs in geographical sympatry and ecological syntopy with multiple congeners: in the Amazonas drainage, rio Essequibo, and coastal drainages of the Guianas: B. alberti , B. arrayae , B. batesi , B. beebei , B. belindae , B. benjamini , B. bennetti , B. bombilla , B. brevirostris , B. bullocki , B. cunia , B. flavipomus , B. hamiltoni , B. hendersoni , B. pinnicaudatus , B. regani , B. sullivani , and B. verdii ; and in the río Paraná-Paraguay drainage with B. bombilla , B. brevirostris , B. draco , and B. gauderio .

Local names. Bolivia: cuchillo; Brazil: sarapó (north), tuvira (south); Ecuador: cuchillo, yayo; Guyana: knife fish; Paraguay: morenita; Peru: macana.

Material examined. 1,032 specimens. Bolivia. Beni (localities from rio Madeira dr., Amazonas dr.) AMNH 39773, 5, 96-113 mm, 6 km SW Costa Marques (Brazil), río Baures (río Blanco) at confluence with río Iténez (río Guaporé), affl. río Mamoré, 12°30′10″S, 064°16′47″W. AMNH 40086 (part), 1, 121 mm, rio Baures, 2 km above mouth, affl. rio Guaporé, affl. río Mamoré , 12°30′32″S, 064°16′46″W . CBF 10256 , 1 , immature, 117 mm , CBF 10257 , 1 , immature, 116 mm, mun. Riberalta, stream nr. lago San José , affl. río Beni, 10°54′47″S, 065°59′49″W . CBF 10258 , 1 , immature, 115 mm , UMSS 7020 , 1 , immature, 137 mm , UMSS 7021 , 1 , female, 201 mm , UMSS 7022 , 1 , immature, 102 mm , UMSS 7023 , 1 , immature, 126 mm, mun. Riberalta, stream nr. San José , affl. río Beni, 10°55′32″S, 066°00′36″W . INHS 37193, 1, 89 mm, 46 km E Estación Biológica del Beni on rd. to San Ignacio, río Moseruna, affl. río Apere , affl. río Mamoré , ca. 14°59′S, 065°48′W . UF 82009 , 2 , 96-142 mm, Bella Vista, río Blanco ( río Baures ), affl. río San Martín , affl. río Guaporé , affl. río Mamoré , 13°16′S, 063°42′W . UMMZ 204297, 2, 89-105 mm, 2 km SW Costa Marques (Brazil), río Iténez ( río Guaporé ), affl. río Mamoré , 12°29′30″S, 064°15′24″W . UMMZ 204632, 6, 90-142 mm, 5 km SW Costa Marques, río Iténez, nr. mouth of río Baures (río Blanco), affl. río Guaporé , affl. río Mamoré , 12°30′30″S, 064°19′00″W . UMMZ 204829, 1, 80 mm, UMMZ 246439, 3, 78- 114 mm, río Baures (río Blanco), nr. mouth, L bank río Iténez ( río Guaporé ), affl. río Mamoré , 12°31′06″S, 064°19′00″W . UMMZ 205163, 3, 87-108 mm, 10 km SE Costa Marques (Brazil), backwater of río Iténez ( río Guaporé ), affl. río Mamoré , 12°30′37″S, 064°12′59″W . Brazil. Amazonas (localities from Amazonas dr.; localities listed from the Mamirauá Reserve [Reserva de Desenvolvimento Sustentável Mamirauá] are in rio Solimões-Japurá floodplain, mun. Alvarães). ANSP 194025, 6 (1 CS), 60-126 mm LEA, INPA 30241 , 8 , 64-114 mm LEA, mun. São Paulo de Olivença, Monte Sinai, Rio Camatiã, affl. rio Solimões , 03°27′34″S, 068°56′00″W [coordinates for São Paulo de Olivença] (listed in Sullivan et al., 2013). BMNH 1998.3.12.83- 101, 19 (3 immature, 136-184 mm, 1 male, 142 mm, 15 unsexed/ measured) , MCP 46933 , 1 ( CS), 70 mm, Mamirauá Reserve, lago Rato , 03º03′01″S, 064º52′23″W . BMNH 1998.3.12.102, 1, male, 186 mm, mun. Tefé, Cabeceira do lago Tefé , rio Tefé , 03°38′01″S, 064°57′59″W . BMNH 1998.3.12.103-104, 2, female, 150-160 mm, Mamirauá Reserve, lago Bolsinha , 03º03′47″S, 064º50′03″W . BMNH 1998.3.12.105, 1, female, 166 mm, MCP 45445 , 33 , 79- 160 mm, Mamirauá Reserve, cano do lago Rato , 03º02′41″S, 064º51′26″W . BMNH 1998.3.12.106-107, 2, female, 163-191 mm, MCP 45490 , 2 (1 female, 152 mm, 1 male, 167 mm), Mamirauá Reserve, Ressaca do Caetono , 02º50′15″S, 064º55′50″W . CU 97641, 1 (paratype), 80 mm, rio Negro upstream of Manaus, rio Negro , 03°05′23″S, 060°27′01″W . CU 97642, 5 (paratypes), 95-104 mm LEA, rio Negro upstream of Manaus, rio Negro , 03°05′35″S, 060°26′50″W . IDSM 457, 6, 72-130 mm, MCP 45297 , 1 , female, 138 mm, mun. Tefé, lago Martelo, rio Tefé , 03°46′56″S, 064°59′39″W . INHS 44484, 4, 101-140 mm, mun. Manaus, inlet to lago Camaleão, Ilha da Marchantaria , rio Solimões floodplain, Amazonas dr., 03°14′22″S, 059°56′37″W . INHS 70542 (part), 4, 71-162 mm LEA, lago Camaleão, Ilha da Marchantaria, rio Solimões floodplain, 03°14′22″S, 059°56′37″W . INPA 8880 , 3 (paratypes), 108-116 mm LEA, 1 examined from photograph in original description (164 mm), INPA 8939 , 1 (paratype), 125 mm LEA, examined from photograph in original description, INPA 8941 , 1 (holotype), 163 mm TL, 126 mm LEA, examined from photograph in original description, Paraná do Paracuúba, nr. mouth of rio Negro and entrance to lago Januari, rio Solimões floodplain, 03°12′36″S, 059°59′24″W . INPA 9945 , 31 , 51-143 mm, Mamirauá Reserve, lago Caetano , 02º50′58″S, 064º55′42″W . INPA 17112 , 20 , 58-132 mm, Paraná do Seixo, lago Jari, rio Purus , 04°54′41″S, 062°27′26″W . INPA 17121 , 1 , 92 mm, Paraná 2, nr. Arumã, rio Purus , 04°46′24″S, 062°11′35″W . INPA 17161 , 2 , 92-108 mm , INPA 19935 , 2 , 72-102 mm, lake nr. Sacado da Santa Luzia, rio Purus , 04°42′17″S, 062°22′26″W . INPA 17170 , 1 , 82 mm, lago Sacado, rio Purus , 04°42′49″S, 062°23′55″W . INPA 17192 , 26 , 72-127 mm, igarapé de Duas Bocas, Paraná do Jari, rio Purus , 04°55′33″S, 062°21′58″W . INPA 19938 , 2 , 70-94 mm, lago Campina, rio Purus , 04°55′59″S, 062°56′25″W . INPA 19940 , 1 , 58 mm, Paraná do Rei, Ilha Careiro, rio Amazonas , Amazonas dr., 03°12′S, 059°44′W . INPA 29259 , 12 , mun. Beruri, igarapéAjará, lagoAyapá, affl. rio Purus , 04º25′07″S, 062°15′36″W (listed in Sullivan et al., 2013) . INPA 33253 , 3 , mun. Manacapuru, Canaboca, rio Solimões floodplain, 03º35′33″S, 060°50′09″W (listed in Sullivan et al., 2013) . INPA 33268 , 3 , mun. Coari, rio Solimões floodplain, 03º51′10″S, 062°28′07″W (listed in Sullivan et al., 2013) . INPA 39074 , 1 , mun. São Sebastião do Uatamã, São José do Jabote, rio Uatamã , 01º56′12″S, 058°17′47″W (listed in Sullivan et al., 2013) . MCP 33368 , 1, 124 mm , MCP 44649 , 2 (1 female [CS], 140 mm, 1 male [CS], 185 mm), Mamirauá Reserve, lago Curuçá Comprido , 03º05′31″S, 064°48′58″W . MCP 33369 , 1, 141 mm, Mamirauá Reserve, lago Curuçá Redondo , 03º06′13″S, 064°49′06″W . MCP 41033 (part), 1, 109 mm, mun. Canutama, igarapé São João on hwy. BR-319, ca. 60 km S Humaitá, affl. rio Ipixuna , affl. rio Purus , 07°56′07″S, 063°20′03″W . MCP 44607 , 1 , female ( CS), 150 mm , MCP 45488 , 1 , female, 116 mm, Mamirauá Reserve, lago Periquito Comprido , 03º04′57″S, 064°46′42″W . MCP 44741 , 2 , immature (1 CS), 126-146 mm , MCP 45296 , 3 , immature, 110-123 mm , MCP 45372 , 2 , male, 137-146 mm , MCP 45415 , 4 , 82-129 mm , MCP 45440 , 2 , immature, 100-136 mm , MCP 45478 , 1 , female, 141 mm, mun. Tefé, igarapé Repartimento, 1.5 km downstream Estrada Agrovila rd. , affl. Lago Tefé ( rio Tefé ), 03º24′25″S, 064º44′08″W . MCP 44742 , 6 (2 immature, 125-142 mm, 4 female [1CS], 104-149 mm), Mamirauá Reserve, lago Periquito Comprido , 03º04′57″S, 064°46′42″W . MCP 44743 , 11 (10 immature [2CS], 86-124 mm, 1 female, 100 mm), mun. Tefé, rio Tefé , 03º37′43″S, 064°59′03″W . MCP 45289 , 1 , immature, 122 mm , MCP 45298 , 1 , female, 123 mm , MCP 45477 , 1 , male, 155 mm, mun. Tefé, igarapé Curupira, Estrada Agrovila rd. , affl. lago Tefé ( rio Tefé ), 03º25′48″S, 064º43′53″W . MCP 45290 , 1 , male, 152 mm , MCP 45442 , 1 , male, 165 mm, Mamirauá Reserve, cano do lago Sapucaia , 03º04′07″S, 064°48′32″W . MCP 45292 , 6 (5 female, 120-153 mm, 1 male, 168 mm), Mamirauá Reserve, lago Promessa , 03º04′29″S, 064°47′02″W . MCP 45293 , 3 (2 female, 135-168 mm, 1, male, 135 mm), Mamirauá Reserve, lago Curuçá Aberto , 03º06′07″S, 064°49′10″W . MCP 45294 , 1 , female, 156 mm, mun. Tefé, lago Caiambé, rio Caiambé , 03º35′40″S, 064º26′58″W . MCP 45291 , 1 , female, 145 mm , MCP 45295 , 1 , female, 176 mm , MCP 45458 , 1 , male, 161 mm, Mamirauá Reserve, lago Secretaria , 03º07′12″S, 064°47′49″W . MCP 45306 , 1 , immature, 132 mm, mun. Maraã, lago Amanã, Igarapé Juá Grande , rio Japurá , 02°28′50″S, 064°48′50″W . MCP 45314 , 5 (4 immature, 95-116 mm, 1 male, 138 mm) , MCP 45417 , 1 , 98 mm , MCP 45371 , 1 , female, 96 mm , MCP 45373 , 3 (1 immature, 94 mm, 2 male, 123-125 mm), mun. Tefé, igarapé Xidarinini, affl. lago Tefé ( rio Tefé ), 03°22′46″S, 064°41′17″W . MCP 45320 , 1 , immature, 130 mm, Mamirauá Reserve, cano do lago Mamirauá , 03º02′41″S, 064º51′26″W . MCP 45327 , 1 , immature, 105 mm, Mamirauá Reserve , lago Sumaumeirinha I, 02º48′26″S, 065º04′33″W . MCP 45412 , 1 , female, 153 mm , MCP 45444 , 2 (1 female, 166 mm, 1 male, 165 mm), Mamirauá Reserve, Ressaca da Vila Alencar , 03º07′41″S, 064°48′04″W . MCP 45413 , 1 , male, 181 mm, Mamirauá Reserve, cano do lago Mamirauá , 03º04′29″S, 064°48′29″W . MCP 45418 , 23 , 54-150 mm, mun. Tefé, lago Jacaré, rio Solimões floodplain, 03°11′11″S, 064°43′05″W . MCP 45441 , 1 , female, 142 mm, Mamirauá Reserve, lago Pirarara , 02º57′04″S, 064º50′04″W . MCP 45443 , 1 , female, 181 mm, Mamirauá Reserve, Ressaca do Itu , 02º49′51″S, 064º57′11″W . MCP 45479 , 1, 124 mm, mun. Tefé, rio Solimões, nr. mouth Paraná Capivara , 03°16′37″S, 064°37′42″W . MCP 45321 , 1 , immature, 141 mm , MCP 45487 , 1 , male, 184 mm, Mamirauá Reserve, lago Bolsinha , 03º03′47″S, 064º50′03″W . MCP 45414 , 1 , female, 173 mm , MCP 45683 , 20 , 86-162 mm, mun. Tefé, Ilha Panamim, rio Solimões floodplain, 03º19′29″S, 064º38′37″W . MCZ 2769, 4, 99-160 mm, mun. Manaus, rio Negro nr. lago Alexo [lago do Aleixo, E Manaus], 03°05′28″S, 059°53′09″W . MCZ 9427 (part), 1, 85 mm, mun. Manaus, lago Hyanuary [lago do Janauari], rio Amazonas floodplain, 03°13′S, 060°00′W . MPEG 967 (part), 29, 42-137 mm, MPEG 970 (part), 3, 57-105 mm, MPEG 971 (part), 1, 47 mm, MZUSP 30063 (part), 1, 50 mm , MZUSP 30065 (part), 1, 32 mm , MZUSP 44060 (part), 3, 52-62 mm , MZUSP 85816 , 4 , 77-133 mm, mun. Tefé, lago Jurupari, rio Tefé , 03°48′S, 065°00′W . MPEG 1123 (part), 5, 65- 85 mm, mun. Tefé, Costa Capivara, rio Solimões , ca. 03°16′38″S, 064°38′09″W . MPEG 22747, 3, 113-151 mm, Mamirauá Reserve, lago Mamirauá , 02º59′38″S, 064°54′26″W . MPEG 22748, 3, 90- 145 mm, Mamirauá Reserve, lago Bolsinho , 03º03′47″S, 064°49′59″W . MZUSP 7803 , 1, 123 mm, mun. Parintins, stream affl. lago José Açu , 02°40′S, 056°37′W . MZUSP 23282 , 1, 107 mm, mun. Coari, Ilha Surubim, upstream Coari , branch of rio Solimões , 03°54′S, 063°19′W . MZUSP 28054 (part), 1, 78 mm , MZUSP 28055 , 1 , 96 mm, Moura, Pedra do Gavião, rio Negro , 01°28′S, 061°38′W . MZUSP 30049 (part), 8, 42-60 mm , MZUSP 30054 , 1 , 58 mm, mun. Tefé, Vista Escura, rio Tefé , no coordinates . MZUSP 30051 , 1 , 68 mm , MZUSP 30056 , 1 , 50 mm , MZUSP 30061 (part), 28, 37-103 mm, mun. Tefé, lago Mucura, rio Tefé , no coordinates . MZUSP 30052 (part), 1, 78 mm, mun. Tefé, Mastro, rio Tefé , no coordinates . MZUSP 30058 (part), 2, 114-115 mm, mun. Maraã, lago Amanã, canal do lago Amanã , affl. rio Japurá , 02°44′S, 64°41′W . MZUSP 75571 (part), 4, 106-152 mm , USNM 306903 , 1, 136 mm , USNM 306919 , 1 , 75 mm LEA, USNM 374466 , 4 , 135-155 mm, lago Camaleão, Ilha da Marchantaria, rio Solimões floodplain, 03°14′22″S, 059°56′37″W . MZUSP 78032 (part), 1, 110, mun. Maraã, Paraná do Castanho, lago Amanã , affl. rio Japurá , 02°44′S, 064°39′W . MZUSP 78954 (part), 1, 92 mm, Costa do Anori, nr. mouth of rio Purus, rio Solimões , 03°46′S, 061°37′W . MZUSP 85814 , 1 , 55 mm, mun. Tefé, Jauari-atuba, rio Tefé , ca. 03°56′S, 065°01′W . MZUSP 94038 , 1, 100 mm , MZUSP 99170 , 7 , 60-135 mm, canal do lago Amanã, affl. rio Japurá , ca. 02°44′S, 064°39′W . MZUSP 95226 (part), 1, 100 mm, mun. Santa Isabel do rio Negro, Paricatuba , lake on margin of rio Negro , ca. 00°31′S, 065°01′W . USNM 300978 , 1 , 94 mm, rio Unini, affl. rio Negro , 01°41′S, 061°31′W [coordinates for mouth of rio Unini]. USNM 306874 , 2 , 91-100 mm LEA, Paraná da Ilha da Marchantaria, rio Solimões floodplain, ca. 03°14′22″S, 059°56′37″W . Goiás (localities from rio Araguaia dr., affl. rio Tocantins, Amazonas dr.). AUM 45436, 9, 107-187 mm, mun. Aruanã , Fazenda Sobrado , margin Aruanã-Cocalinho rd. , 14°45′51″S, 050°57′50″W . MZUSP 89218 (part), 1, 114 mm, mun. Aruanã, Fazenda Viplan, on hwy. GO 334, floodplain of rio do Peixe , 14°20′11″S, 050°46′31″W . Mato Grosso. BMNH 1900.4.14.91-94 (part), 1, 98 mm, mun. Carandàzinho, rio Cuiabá, affl. rio Paraguai , Paraná dr., ca. 16°27′S, 056°08′W . BMNH 1982.9.24.132, 1, 78 mm, Corgo do Gato [córrego do Gato], on hwy. BR-158, affl. rio Suiazinho, affl. rio Suiá Missu , affl. rio Xingu , Amazonas dr., ca. 12°56′S, 051°51′W . MCP 30786 , 1, 106 mm, mun. Nova Ubiratã, rio Celeste ca. 9 km W Nova Ubiratã on rd. to Sorriso , affl. rio Tapajós , Amazonas dr., 13°03′08″S, 055°21′13″W . MCP 44451 , 1 , 87 mm, mun. Nova Mutum, Córrego Ranchão on Nova Mutum-Santa Rita do Trivelato hwy., MT-235, affl. rio Tapajós, Amazonas dr., 13°44′35″S, 055°50′08″W . MZUSP 25138 , 2 , 102-111 mm , MZUSP 25143 , 1, 147 mm, mun. Cáceres, Ilha da Taiamã [Estação Ecológica Taiamã], rio Paraguai , Paraná dr., 16°53′S, 057°27′W [coordinates from center Ilha da Taiamã ] . MZUSP 57478 , 1 , 67 mm, mun. Xavantina, rio Areões, affl. rio das Mortes, affl. rio Araguaia , affl. rio Tocantins, Amazonas dr., 14°39′S, 052°07′W . MZUSP 77724 , 6 , 108-147 mm, rio Juruena, ca. 1 km upstream mouth rio Arinos, affl. rio Tapajós , Amazonas dr., ca. 10°26′S, 58°20′W . MZUSP 88593 , 15 , 83-215 mm, mun. Cocalinho, stream, affl. Corixo da Saudade, ca. 17 km NW Cocalinho on hwy. MT-326, affl. rio Araguaia , aff rio Tocantins, Amazonas dr., 14°19′35″N, 051°06′25″W . MZUSP 95068 (part), 18, 93-155 mm , MZUSP 100307 , 18 , 89-152 mm, mun. Barão de Melgaço, rio Mutum, between Vila de Mimoso and Joselândia (Pantanal de Paiaguás), rio Paraguai , Paraná dr., 16°19′30″S, 055°49′59″W . MZUSP 95736 , 40 , 72-179 mm, stream, affl. rio Culuene, on rd. to Cachoeira do Adelino, affl. rio Xingu , Amazonas dr., 13°48′12″S, 053°13′35″W . MZUSP 96252 , 3 , 94-106 mm, mun. Paranaíta, rio Teles Pires, affl. rio Tapajós , Amazonas dr., 09°25′44″S, 056°32′36″W . MZUSP 96667 , 1 , 87 mm, mun. Barão de Melgaço, swamp, 1 km Vila de Mimoso, Pantanal de Paiaguás, affl. rio Cuiabá, affl. rio Paraguai , Paraná dr., ca. 16°17′S, 055°48′W . MZUSP 100084 , 2 , 75-110 mm, mun. Paranaíta, just upstream of Sete Quedas, rio Teles Pires , affl. rio Tapajós , Amazonas dr., 09°24′05″S, 056°33′49″W . USNM 301981 , 2 , 103-124 mm, rio Batovi, affl. rio Xingu, Amazonas dr., ca. 11°56′S, 053°36′W . Mato Grosso do Sul (localities from rio Paraguai dr., Paraná dr.). FMNH 108538, 8, 55-91 mm, Corumbá, bay on left margin rio Vermelho , affl. rio Miranda , 19°37′13″S, 056°57′16″W . MUSM 17103 , 2 , 84-95 mm, side channel, rio Abobral , 19°27′22″S, 057°01′38″W . MZUSP 48311 (part), 1, 98 mm , MZUSP 48312 , 3 , 85-95 mm, mun. Coxim, Fazenda Santo Antonio (Baía da Sede), Pantanal do Paiaguás , affl. rio Coxim ( rio Taquari ), ca. 18°30′S, 054°45′W . MZUSP 59443 , 25 , 83-133 mm, mun. Corumbá, on rd. from Nhecolândia to BR-262, rio Negro , 19°17′16″S, 057°03′39″W . MZUSP 83607 (part), 1, 87 mm, mun. Coxim, Paraguai Lagoa, source of Ribeirao dos Veados, affl. rio Coxim ( rio Taquari ), 18°25′21″S, 054°50′06″W . Pará (localities from Amazonas dr.). ANSP 194517, 32, 74-140 mm, mun. Porto de Moz , beach, 3 km downstream Porto de Moz, rio Xingu , 01°43′54″S, 052°15′16″W . INPA 4209 , 2 , 103-155 , Ilha de Babaguara, rio Xingu (no coordinates) . INPA 7267 , 2 , 108-110 mm, rio Tapajós, nr. mouth rio Cupari , ca. 03°43′S, 055°24′W . INPA 32703 , 1 , Jacareacanga, igarapé do Cocho, rio Crepori , affl. rio Tapajós , 06°44′54″S, 056°54′43″W (listed in Sullivan et al., 2013) . INPA 33192 , 1 , mun. Almeirim, Paranaguara, rio Amazonas floodplain, 01°44′29″S, 053°10′15″W (listed in Sullivan et al., 2013) . MCP 23359 (part), 1, 107 mm, Concórdia do Pará, rio Bujarú, affl. rio Guamá , affl. Baía de Marajó, ca. 02°06′S, 047°56′W . MCZ 9440, 1, 52 mm, Belém and environs., Báia de Marajó, ca. 01°27′S, 048°29′W . MCP 49398 , 3 , mun. Santarém, Cachoerinha do Mentai, rio Mentai , affl. Rio Arapiuns , affl. Rio Tapajós , 02°43′12″S, 055°36′15″W . MCP 49400 , 7 , mun. Curuá, Lago Preto, Ilha São Luiz , rio Amazonas floodplain, 02°06′22″S, 055°10′17″W . MCP 49411 , 4 , mun. Alenquer, small stream affl. rio Curuá , 01°36′13″S, 054°55′10″W . MPEG 5813, 1, 115 mm, mun. Almeirim, Pesqueiro da Ilha, no precise locality, rio Amazonas , 01°31′S, 052°35′W [coordinates for Almeirim]. MPEG 9758, 10, 46-105 mm, mun. Tomé-Açu, igarapé Arrainha, affl. rio Acará-Mirim , affl. rio Acará , affl. Baía de Marajó, 02°25′11″S, 048°12′13″W . ZUEC 12328, 1, mun. Belterra, Igarapé do Mato Grosso, nr. Jaguarari , affl. rio Tapajós , 02°55′01″S, 055°03′54″W . ZUEC 12329, 1, Igarapé Jandá, nr. Piquiatuba, affl. rio Tapajós , 03°00′37″S, 055°06′16″W . ZUEC 12330, 1, mun. Belterra, Igarapé Dominguinho, nr. Piquiatuba , affl. rio Tapajós , 03°00′48″S, 055°06′22″W . ZUEC 12336, 5, mun. Santarém, rio Mentai at Cachoeirinha do Mentai , affl. rio Arapiuns , affl. rio Tapajós , 02°43′12″S, 055°36′15″W . Rondônia (localities from rio Madeira dr., Amazonas dr.). FMNH 117760, 4, 82-104 mm, Maciel , rio Guaporé , affl. rio Mamoré , 12°30′S, 062°20′W . INPA 9721 , 19 , 100-146 mm , INPA 9727 , 18 , 56-148 mm, rio Pacaás Novos, nr. confluence with rio Mamoré , ca. 15 km Guajará Mirim, 10°51′S, 065°16′W . INPA 9724 , 2 , 49-131 mm, rio Mamoré, just upstream Guajará Mirim , ca. 10°47′S, 065°20′W . INPA 9729 (part) 1, 127 mm, mouth of rio Pacaás Novos, ca. 15 km Guajará Mirim, rio Mamoré , 10°51′S, 065°16′W . INPA 19958 , 1, 105 mm, Surprêsa, at rio Mamoré-Madeira confl., ca. 11°53′S, 064°59′W . MPEG 1120 (part), 1, 95 mm, rio Pacaás Novos, Guajará Mirim, affl. rio Mamoré , ca. 10°51′S, 065°16′W . MPEG 1121 (part), 2, 111-120, rio Pacaás Novos, 20 km upstream Guajará Mirim, affl. rio Mamoré , ca. 10°56′15″S, 065°16′29″W . UFRO-I 6463, 30, 125-160 mm, mouth rio Cautário, affl. rio Guaporé, affl. rio Mamoré , 12°10′51″S, 064°34′00″W . UFRO-I 6465, 1, 130 mm, UFRO-I uncat. (field number CAU2010010701 ), 2, 141-145 mm, mouth of rio Cautário, affl. rio Guaporé, affl. rio Mamoré , 12°11′22″S, 064°35′20″W . UFRO-I 6466, 5, 75-112 mm, UFRO-I 6469, 5, 93-105 mm, Colocação Três Praias, rio Jaciparaná , 09°27′29″S, 064°25′22″W . UFRO-1 6468, 26, 85-155 mm, Furo Variante, lago Cuniã, rio Madeira floodplain, 08°21′17″S, 064°30′11″W . UFRO-I uncat. (field number CUN2008120102 ), 4, 115-153 mm, igarapé do Campo, lago Cuniã, rio Madeira floodplain, 08°19′14″S, 064°28′05″W . USNM 301980 , 10 , 98-132 mm, Brazil-Bolivia border, region between Guajará-Mirim and Mato Grosso, rio Guaporé , affl. rio Mamoré , affl. rio Madeira , Amazonas dr., 12°41′S, 063°07′W [coordinate taken half-way from Guajará-Mirim to Mato Grosso, listed coordinate is in Bolivian territory nr. Guayara-Mirín]. Roraima. INPA 30748 , 11 , INPA 30749 , 8 , rio Branco, near Boa Vista, affl. rio Negro , Amazonas dr., 02°47′31″N, 060°40′09″W . Tocantins (localities in rio Tocantins dr., Amazonas dr.). MCP 40909 , 1, 156 mm , MCP 40912 , 1, 165 mm, mun. Porto Nacional, Córrego da Prata in area of PFI São João , 10°26′43″S, 048°21′51″W . MZUSP 52139 , 3 , 67-111 mm , MZUSP 73436 , 3 , 85-124 mm, mun. AraguAçu, Fazenda Praia Alta 2, Araguaçu - Barreira do Piqui hwy., 27 km N AraguAçu, rio Água Fria, affl. rio Javaés , affl. rio Araguaia , 12°43′S, 049°55′W . Ecuador (localities from río Napo dr., Amazonas dr.). Sucumbios. FMNH 102275, 2, 113-122 mm, stream affl. río Juntuncocha, ca. 1 km upstream Laguna Jatuncocha, affl. río Yasuni , affl. 01°00′06″S, 075°31′36″W . FMNH 102276, 8, 69-107 mm LEA, lago Anangucocha, 01°28′29″S, 077°33′44″W . FMNH 102277, 1, 118 mm, stream affl. río Juntuncocha, ca. 2 km upstream Laguna Jatuncocha, affl. río Yasuni , 01°00′18″S, 075°31′24″W . FMNH 102286, 1, 117 mm, Laguna Augacocha, affl. río Cuyabeno, affl. río Aguarico , ca. 00°02′N, 076°12′W . FMNH 102287, 2, 90-107 mm, río Cuyabano , ca. 3 km Laguna Grande de Cuyabeno,affl.ríoAguarico, 00°01′30″N, 076°13′12″W . Guyana (localities from Essequibo River dr.). Upper Tukutu-Upper Essequibo. ANSP 185107, 1, 109 mm, 1.1 km NE Massara, Massara’s Landing , Rupununi River , 03°53′41″N, 059°17′37″W . AUM 47959, 1, 150 mm, Rupunini River, upstream Yupukari landing, on beach, 03°39′45″N, 059°30′32″W . Paraguay. Itapúa. NRM 42254, 1, 107 mm, Arroyo Aguapey, affl. rio Paraná, Paraná dr., 27°17′03″S, 056°16′35″W . Peru (localities from Amazonas dr.). Loreto (localities listed from nr. Jenaro Herrera are from the río Ucayali dr., mun. Requena ). ANSP 167728, 2, 99-103 mm, small floodplain lake, río Nanay , ca. 1 km upstream Minchana [Mishana], ca. 03°52′S, 073°29′W . ANSP 192030, 1, 88 mm, caño Santa Rita, R bank affl. río Nanay, nr. pueblo Pampa Chica , 03°45′23″S, 073°17′28″W . CAS 98605, 1, 107 mm, stream, affl. río Itaya , ca. 03°48′S, 073°16′W . FMNH 84277, 1, 115 mm, lake, affl. río Mamon [Momón], affl. río Nanay , ca. 03°41′S, 073°16′W . FMNH 96035, 3, 82-102 mm, quebrada Michana [Mishana], affl. río Nanay , ca. 03°53′S, 073°29′W . FMNH 113876, 2, 95-100 mm, cocha Huanayo, affl. río Pastaza, affl. río Marañón , 04°10′30″S, 076°33′03″W . INHS 36934, 2, 64-95 mm, Felipe cocha, nr. 25 de Enero, 12 km Iquitos on Iquitos-Quistococha rd., affl. río Itaya , ca. 03°49′S, 073°19′W . INHS 39773, 2, 60-93 mm, lago Pabellon, upstream Paucarillo base camp, río Oroso , affl. río Nanay , ca. 03°36′S, 074°02′W . INHS 39908, 1, 102 mm, nr. Corrientillos, rio Nanay upstream Santa Clara , ca. 03°46′S, 073°20′W . INHS 43902, 1, 119 mm, quebrada Shushuna, rd. to Corrientillos, affl. rio Nanay , 03°49′48″S, 073°20′14″W . MUSM 6937 , 3 , 85-173 mm, Padre Cocha, quebrada Chancacayo, affl. río Nanay , 03°41′55″S, 073°16′59″W . MUSM 7123 (part), 1, 161 mm, Laguna Rimachi, río Pastaza, affl. río Marañón , 04°25′S, 076°43′W . MUSM 14498 (part), 7, 68-142 mm, Puesto de Vigiliancia Arcadia, río Napo , 00°59′37″S, 075°18′30″W . MUSM 16062 , 1, 101 mm, stream, Jeberos, km 44, Iquitos-Nauta rd. , ca. 04°05′S, 073°27′W . MUSM 18553 , 1, 102 mm, Laguna Rimachi, nr. caño Rimachi, affl. río Pastaza , affl. río Marañón , 04°25′49″S, 076°40′20″W . MUSM 44678 , 16 (8 immature, 85-178 mm, 8, female, 126-175 mm), stream nr. Jenaro Herrera , 04°53′59″S, 073°38′51″W . MUSM 44684 , 1 , female, 127 mm, stream nr. Jenaro Herrera , 04°53′35″S, 073°39′01″W . MUSM 44696 , 4 (3 immature, 150-159 mm, 1 male, 167 mm), stream nr. Jenaro Herrera , 04°51′51″S, 073°38′45″W . MUSM 44707 , 4 , immature, 99-130 mm, stream nr. Jenaro Herrera , 04°54′40″S, 073°39′29″W . MUSM 44730 , 31 (19 immature, 61-132 mm, 8 female, 118-148 mm, 4 male, 150-163 mm), stream nr. Jenaro Herrera , 04°54′49″S, 073°39′43″W . MUSM 44749 , 1 , immature, 84 mm, stream nr. Jenaro Herrera , 04°54′29″S, 073°39′43″W . MUSM 44753 , 1 , immature, 88 mm, stream nr. Jenaro Herrera , 04°54′54″S, 073°39′25″W . MUSM 44758 , 4 (3 immature, 108-118 mm, 1 female, 93 mm), cocha Supay, nr. Jenaro Herrera , río Ucayali floodplain, 04°55′16″S, 073°42′32″W . MUSM 44765 , 7 (3 immature, 60-149 mm, 3 female, 107-169 mm, 1 male, 195 mm), stream nr. Jenaro Herrera , 04°54′36″S, 073°39′58″W . NRM 13522 (part), 1, 90 mm, caño Sacarita, opposite Pebas, río Ampiyacu , ca. 03°19′S, 071°50′W . NRM 27523 (part), 1, 69 mm, lago Matamata, affl. caño, río Yavarí ( rio Javari ), upstream Atalaia do Norte ( Brazil ), 04°12′S, 070°17′W . UF 114499 , 4 , 110-120 mm, stream, km 23 on Iquitos-Nauta rd., affl. río Nanay , 03°56′38″S, 073°23′54″W . UF 117124 , 7 , 53-105 mm, río Nanay , 03°43′S, 073°15′W . UF 131122 , 1, 120 mm, Iquitos , specimen collected by ornamental fish catchers, no coordinates . UF 148472 , 1 , male, 192 mm, small stream, nr. Jenaro Herrera, affl. quebrada Parnayari , ca. 04º54′S, 073º37′W . UF 184010 , 1 , immature, 105 mm, stream nr. Jenaro Herrera , 04°52′42″S, 073°38′51″W . UF 184020 , 4 , immature, 86-125 mm, stream nr. Jenaro Herrera , 04°55′19″S, 073°38′57″W . UMMZ 224602, 1, 137 mm, nr. Santa Ana, río Tahwayo [Tahuayo], 04°17′S, 073°11′W . UMMZ 224606, 1, 131 mm, nr. Pebas, río Ampiyacu , ca. 03°19′S, 071°50′W . USNM 86845 , 1 , 90 mm, Iquitos , ca. 03°45′S, 073°12′W . ZMH 9637, 5, 102-132 mm, region between Iquitos and Leticia, río Amazonas, no coordinates. ZMH 11628 (part), 5, 100-123 mm, between Iquitos and Leticia, río Amazonas , no coordinates. Madre de Dios (localities from río Madre de Dios, affl. río Beni , affl. rio Madeira , Amazonas dr.) . MUSM 21754 , 1 , Pozo Santa Elena , ca. 12°50′S, 069°17′W . MUSM 22642 , 1 (part), Las Piedras, Planchon las Piedras , quebrada Planchón , affl. río Tahuamanu [also known as río Las Piedras], ca. 12°30′S, 069°14′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. 46. Brachyhypopomus walteri. a. MCP 45291 (WC16.180598), female, 145 mm TL (head, and body in lateral and dorsal view); b. MCP 45292 (WC05.190598), male, 168 mm TL (body in lateral view); Brazil, rio Solimões-Japurá confluence, Amazonas dr. Note sexual dimorphism in caudal-filament length. Specimen fixed in formalin and preserved in EtOH. Scale bars = 5mm.

Fig. 47. Collection records for Brachyhypopomus walteri (circles). Holotype location is marked with an open symbol. Elevation data refers to altitude above mean sea level (see Fig. 2 for legend).