Brachyhypopomus bullocki Sullivan & Hopkins, 2009

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 : 702-704

Brachyhypopomus bullocki Sullivan & Hopkins, 2009

( Fig. 19 ; Tables 2-5, 8)

Hypopomus sp. 4 . -Heiligenberg & Bastian, 1980: 197, fig. 1, black and white photograph ( Brazil, Amazonas, rio Negro, species and EOD diversity).

Brachyhypopomus bullocki . - Sullivan, 1997: 91 (description in unpublished thesis with disclaimer stating that nomenclatural acts not available, a nomen nudum).

Brachyhypopomus sp. - Hopkins, 1999: 1218, fig. 1, black and white photographs of breeding male and female (electric organ morphology and impedance matching).

Brachyhypopomus sp. J . - Crampton & Albert, 2006: 672, fig. 23.8, position in phylogenetic tree; 681 notes on EODs (gymnotiform species and EOD diversity).

Brachyhypopomus bullocki Sullivan & Hopkins, 2009: 185-186 , fig. 1, black and white photograph of holotype (breeding male) and breeding male and female paratypes; 191, fig. 3, EODs (original description, type locality – Venezuela, Meta State, río Metica-Meta dr.). -Crampton, 2011: 176, table 10.2, species list; 179, figs. 10.2-10.3, phylogeny, geographical and ecological distributions (gymnotiform biology). - Carvalho, 2013: 181-185, figs. 41-43, position in phylogeny (phylogenetic systematics of Rhamphichthyoidea ). - Tagliacollo et al., 2016: 28, fig. 5 (phylogeny of Gymnotiformes ). - Crampton et al., 2016: 1-66, table 1, 3-4, figs. 1-7, 18-20 (phylogeny, biogeography and ecology of Brachyhypopomus ).

Diagnosis. Brachyhypopomus bullocki is diagnosed from congeners by the following cobination of characters: orbital diameter 14.2-18.5% HL, vs. 5.9-14.1% in all congeners except B. batesi , B. benjamini , B. brevirostris , B. cunia , B. flavipomus , B. hamiltoni , B. hendersoni , B. janeiroensis , B. provenzanoi , and B. walteri ; caudal filament length 31.4- 62.9% LEA, vs. 14.1-30.0% in B. batesi , B. benjamini , B. hamiltoni , and B. provenzanoi ; precaudal vertebrae 15-17, vs. 18-21 in B. brevirostris , B. flavipomus , and B. janeiroensis ; distinct dark suborbital stripe absent, vs. present in B. cunia and B. walteri ; interorbital distance 24.0-30.0% HL, vs. 16.4-20.4% in B. hendersoni .

Description. Head and body shape, and pigmentation illustrated in Fig. 19 , and in original description. Meristic and morphometric data for examined specimens presented in Tables 2-5 and 8. Body shallow to moderate in depth. Head short and moderate to broad in depth. Dorsal profile of head convex from occiput to snout, ventral profile of head slightly concave between operculum and snout, snout rounded. Eye large. Upper jaw with moderate to acute sigmoidal angle between premaxillary and maxillary portions in lateral view. No accessory electric organ over operculum. Gill filaments on first gill arch 33-36 (median 34, n = 6). Pectoral fin moderate to broad in width, pectoral-fin rays 11-15 (mode 13). Precaudal vertebrae 15-17 (mode 16), including 1-2 transitional vertebrae (mode 2). Anal-fin origin slightly (<0.25 HL distance) anterior or posterior to, or near, tip of pectoral fin. Anal-fin rays 196-233. Dorsal rami of recurrent branch of anterior lateral line nerve visible in most juvenile and some lightly-pigmented adults – mostly in anterior third of body. Middorsal region of body scaled. Rows of scales above lateral line 4-7 (mode 6). Lateral line continuous. Epidermal canals very sparse and in some specimens more or less absent; when present located only in posterior half of body. Discontinuous meandering horizontal scratch-like epidermal canals in dorsal flank, midway between lateral line and dorsal midline, variably present. Some short epidermal canals as short grooves close to and parallel to lateral line, mainly in posterior third of body. Three bilateral horizontal columns of electrocytes at anal-fin terminus, and at a mid-point between anal-fin terminus and tip of caudal filament in immature, mature female, and mature male specimens. Tip of caudal filament free of electrocytes in some specimens. Caudal filament moderate in length to long.

Coloration. ( Fig. 19 ). Background pale straw to dark tan. Dorsal region without prominent depigmented pale stripe extending along midline from occipital region to base of caudal filament. Irregular dark saddles crossing dorsal surface in anterior third of body, extending ventrally as indistinct bands which break up before reaching lateral line. Indistinct bands and irregular patches over dorsal surface in posterior two thirds of body, not forming saddles that cross entire dorsal surface. Banding absent or faint in posterior third of body. Sparse indistinct dark markings over rest of flank. Indistinct series of dark dots form a line along upper margin of anal-fin pterygiophores in posterior third of body. Caudal filament darker with sparse irregular darker bands and dark tip; underwater, tip of caudal filament resembles root tips of water hyacinths. Head with sparse dark chromatophores on cheeks and operculum, darker dorsally. Eye without prominent suborbital patch, or stripe, of chromatophores/subcutaneous pigmentation. Pectoral and anal-fin membranes hyaline. Pectoral-fin rays hyaline with light scattering of brown chromatophores. Anal-fin rays with scattered chromatophores, sometimes fusing to form darker patches. Color in live individuals similar to preserved specimens, with opercular region usually rosy due to underlying gills.

Size. Moderate adult size, largest specimen examined 221 mm TL, 121 mm LEA (n = 363). Largest male specimen examined 221 mm TL, 121 mm LEA (n = 12). Largest female specimen examined 152 mm TL, 96 mm LEA (n = 11).

Sexual dimorphism. Males attain larger sizes than females. Breeding males develop very elongated caudal filaments in comparison to immature individuals and breeding females, and reach greater lengths ( Figs. 19 a-b), but do not exhibit 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. Tip of caudal filament in large males often exhibits paddle-like laterally compressed structure. Caudal filament of males often entirely free of electrocytes near tip, with electrocytes sometimes absent in as much as the terminal 25% of caudal filament. No sexual differences in pigmentation.

Geographic distribution. Brazil, Colombia, Guyana, and Venezuela ( Fig. 7 ). Widespread throughout Orinoco drainage, rio Negro drainage (Amazonas drainage), upper rio Branco (affl. rio Negro), and upper and middle portions of the Essequibo River drainage.

Ecological notes. Sullivan & Hopkins (2009) report B. bullocki from low-conductivity (<25 μScm-1) shallow clear water in Mauritia palm swamps and open savanna, and from small pools fed by streams (Orinoco), and from a low-conductivity blackwater stream (rio Negro), but report its absence from high-conductivity sites (> 100 μScm-1) in the Venezuelan llanos. WGRC and NRL collected B. bullocki from low-conductivity streams, Mauritia palm swamps, and savanna gallery forest in the vicinity of San Fernando de Atabapo, Amazonas, Venezuela. Here the following water parameters were recorded at the time of sampling: conductivity 7-13 µScm-1, dissolved oxygen 1.6-3.8 mgl-1, temperature 25.8-28.2°C, and pH 3.1-4.5. Reproductive biology is unknown. Stomach contents comprise aquatic insect larvae, primarily Chironomidae larvae, and other small aquatic invertebrates (WGRC unpublished data).

Co-occurring congeners: In the Orinoco drainage, we captured B. bullocki in ecological syntopy with B. brevirostris , B. provenzanoi , and B. sullivani , and it may also occur in syntopy with B. beebei and B. regani – both known from low-conductivity systems in the Orinoco. Brachyhypopomus bullocki also occurs in sympatry but ecological allotopy with B. diazi , which is restricted to systems with higher conductivity (Sullivan & Hopkins, 2009). In the rio Negro and Essequibo River drainages, both low-conductivity systems, B. bullocki occurs in sympatry and syntopy with B. batesi , B. beebei , B. brevirostris , B. hendersoni , B. pinnicaudatus (only near mouth of rio Negro), B. regani , B. sullivani , and B. walteri .

Local names. Brazil: sarapó; Colombia and Venezuela: cuchillo.

Material examined. 332 specimens. Brazil. Amazonas (localities from rio Negro dr., Amazonas dr.). CU 94737, 1, stream above mouth rio Branco , rio Branco dr., ca. 01°20′S, 061°54′W . INPA 19949 , 1, 135 mm , INPA 19951 , 1, 173 mm, Arquipelago das Anavilhanas , 02°41′S, 060°44′W . MZUSP 54578 , 2 (1 immature, 68 mm, 1 female, 117 mm) , MZUSP 95226 (part), 26 (10 immature, 74-125 mm, 12 female, 98-136 mm, 4 male, 136-148 mm), mun. Santa Isabel do rio Negro, Paricatuba , lake on margin of rio Negro , 00°31′S, 065°01′W . Roraima (localities from rio Branco dr., affl. rio Negro, Amazonas dr.). INPA 7370 , 1 , igarapé do Gentil , 34 km Boa Vista on Boa Vista to Bonfim hwy., 02°58′N, 060°26′W . INPA 7425 , 1, 132 mm, Boa Vista, on rd. to Bonfim , 02°49′N, 060°35′W . INPA 9829 , 1 , 73 mm, Ilha de Maracá, rio Uraricoera , 03°22′N, 061°23′W . Colombia (localities from río Meta dr., Orinoco dr.). Meta. ANSP 128100, 2, Hacienda Mozambique, Laguna N lago Mozambique at outlet to río Metica , affl. río Metica , 03°58′N, 073°04′W . ANSP 138024, 17 (paratypes), 150-216 mm, 2 examined from photograph in original description (1 male 215 mm; 1 female, 176 mm), ANSP 187477, 1 (holotype), 221 mm, examined from photograph in original description, rancho Llano Grande, N Hacienda Mozambique, affl. río Metica , 04°02′N, 073°03′W . AUM 35487, 2, 108-112 mm, 19 km S Puerto Gaitán, Estero ca. 1 km up caño Pajaro Grande, affl. río Manacacías , ca. 04°09N, 072°07′W . UF 19475 , 1, 114 mm , UF 111998 , 1, 120 mm, ca. 10 km SE Puerto Gaitán , 04°15′N, 072°00′W . UF 33734 , 1, 115 mm, ca. 15 km E Puerto Gaitán , 04°18′N, 071°55′W . UF 148456 , 1 , 70 mm , UF 148457 , 1, 125 mm , UF 148531 , 1 , 85 mm, ca. 4.7 km W Puerto Gaitán, affl. río Yucao , 04°18′N, 072°07′W . Vichada. IAVH-P uncat. 1, 110 mm (photograph from S. Gavassa, specimen ca. 110 mm), mun. Santa Rosalia, El Dera ranch, 46 km Santa Rosalia, small creek, affl. caño Grande, affl. río Tomo , Orinoco dr., 04°50′59″N, 070°33′52″W . Vuapés. USNM 320021 , 2 , 142-146 mm, río Mitu, affl. río Vuapes , affl. rio Negro , Amazonas dr., ca. 01°16′N, 070°13′W . Guyana. Upper Demerara Berbice. ROM 62548, 1 (of 3), 111 mm, unnamed creek ca. 7 km. SE Tambikabo inlet, Essequibo River, Essequibo River dr., 04°45′N, 058°43′W . Upper Takutu-Upper Essequibo. AUM 35813, 1, 79 mm, Rupununi River at Massara’s Landing , 1.1 km NE Massara, Essequibo River dr., 03°53′41″N, 059°17′37″W . AUM 50025, 2, 123-133 mm, lake nr. Yukupari, Essequibo River dr., 03°41′38″N, 059°23′40″W . BMNH 1972.7.27.456-457, 2, 65-95, small ponds in Rupununi River, Essequibo River dr., ca. 02°52′N, 059°32′W . BMNH 1972.7.27.458-518 (part), 27, 42-100 mm, Karanambo creek, Rupununi River, Essequibo River dr., 03°45′11″N, 059°18′36″W . BMNH 1972.7.27.519-525, 1, 110 mm, Rupununi River, Essequibo River dr., no coordinates. CU 71946, 4, to 141 mm, 15 mi. E Lethem, pond nr. Moco-Moco Creek , Takutu River , affl. rio Branco , affl. rio Negro , Amazonas dr., 03°19′N, 059°40′W . CU 71947, 1, ca. 2 km Lethem, confl. Buru and Arara Creeks, Takutu River , affl. rio Branco , affl. rio Negro , Amazonas dr., 02°23′N, 059°48′W . MCZ 48555, 1, male, 149 mm, 5 mi. N Manari Ranch, Takutu River, affl. rio Branco, affl. rio Negro , Amazonas dr., 03°26′N, 059°46′W . USNM 190552 , 2 , 93-107 mm, Rupununi, Essequibo River dr., no coordinates. Region not specified. AMNH 35363, 1, 85 mm, Kora-Kora creek , Demerara [Essequibo River dr.?], no coordinates . Venezuela. Amazonas (localities from Orinoco dr.). ANSP 188069, 3, Pozo de Lucas nr. San Fernando de Atabapo , affl. río Orinoco , ca. 03°56′N, 067°36′W . CU 83825, 13, nr. Puerto Ayacucho, affl. río Orinoco , ca. 05°39′N, 067°31′W . CU 83832, 2, nr. San Fernando de Atabapo, affl. río Orinoco , ca. 04°03′N, 067°42′W . INHS 61558, 1, 90 mm, caño Pozo Azul, nr. Puerto Ayacucho, affl. río Orinoco , 05°45′49″N, 067°29′21″W . MAC-PAY 01237, 2, Laguna Provincial, ca. 20 km N Puerto Ayacucho, affl. río Orinoco , ca. 05°50′N, 067°37′W (listed in Sullivan & Hopkins, 2009) . MCNG 21515, 4, Maroa, río Guainía , 02°43″N, 067°33′W . MBUCV-V 15751 , 1 , female, 152 mm, río Autana, ca. 8 km confl. with río Sipapo , 04°43′N, 067°45′W . UMMZ 228985, 1, 181 mm, creek nr. Puerto Ayacucho, affl. río Orinoco , ca. 05°39′N, 067°37′W . UF 77949 , 1 , male, 125 mm, Yavi, río Ventuari , ca. 05°25′N, 066°00′W . UF 177348 , 3 , immature (2 CS), 105-183 mm, on rd. from San Fernando de Atabapo to Santa Barbara, affl. río Orinoco , 03°58′59″N, 067°38′27″W . UF 177349 , 1 , female, 132 mm, caño Viejita, on rd. from San Fernando de Atabapo to Santa Barbara, affl. río Orinoco , 03°55′59″N, 067°36′34″W . Anzoátegui. MHNLS 5859 , 1 , MHNLS 5974 , 1 , MHNLS 6088 , 1 , MHNLS 6195 , 25 , Laguna de Mamo, río Orinoco floodplain, Orinoco dr., ca. 08°25′56″N, 063°07′10″W (listed in Sullivan & Hopkins, 2009) . Apure (localities from Orinoco dr.). ANSP 128106, 1, ca. 13 km N San Fernando de Apure, Camaguán swamp, hwy. to San Fernando de Apure, affl. río Apure, 08°00′N, 067°28′W . ANSP 165517, 1, female, 112 mm, Morichal along San Fernando de Apure-Puerto Páez hwy., affl. río Capanaparo , 06°57′N, 067°28′W . AUM 22501, 1, 121 mm, Puerto Páez-San Fernando rd., río Claro, affl. río Cunaviche , 07°09′08″N, 067°38′06″W . CU 94795, 6, CU 94796, 28 (1 CS), CU 94797 , 19 (1 CS), CU 94798 , 4 , 10 km. S Santa Juana in Parque Nacional ( PN) los Santos Luzardo, affl. río Capanaparo , 06°55′N, 067°27′W . CU 94799, 1, Caño La Pica, 12 km S Santa Juana, in PN los Santos Luzardo, affl. río Capanaparo , 06°54′N, 067°30′W . CU 94800, 8, blackwater lake E of rd. S from Santa Juana, affl. río Capanaparo , 06°56′N, 067°25′W . INHS 27703, 2 (paratypes), 102-141 mm, on San Fernando de Apure-Puerto Páez hwy., río Cinaruco , 06°33′06″N, 067°30′43″W . MBUCV-V 19847 , 5 (3 measured: 1 female, 133 mm, 2 male, 141-152 mm), río Capanaparo , no coordinates . MBUCV-V 21369 , 1 , female, 130 mm, La Montañita, on San Fernando de Apure-Puerto Páez hwy., río Claro, affl. río Cunaviche , 07°09′N, 67°38′W . MCNG 2273, 1, MCNG 4842, 3, MCNG 4451, 3, MCNG 10261, 1, MCNG 10754, 1, MCNG 11525, 6, MCNG 28643, 2, TNHC 11833, 1, 115 mm, TNHC 11850, 6, 104-127 mm, TNHC 17535, 1, 108 mm, caño Maporal, nr. módulo de UNELLEZ, río Caicara , affl. río Apure, ca. 07°24′N, 069°32′W . TNHC 17486, 3 (1 immature, 135 mm, 1 female, 140 mm, 1 male, 179 mm), río Caicara , affl. río Apure, 07°24′N, 069°32′W . UMMZ 217073, 1, 109 mm, ca. 20 km N Paso de Caballo, río Guariquito , affl. río Apure, 08°36′N, 067°08′W . USNM 260261 , 2 , caño Caicara, at bridge rd. from Montecal , affl. río Apure, 07°22′N, 069°21′W . Bolívar (localities from Orinoco dr.). ANSP 187476, 3, 93-120 mm, Morichal Zamori on Maripa-Ciudad Bolivar hwy, affl. río Orinoco , 07°28′N, 064°54′W . ANSP 189185, 1, 06°57′N, 064°50′W, MBUCV-V 24065 , 4 , 2 measured, female, 115-122 mm, Morichal de los Pavones, affl. río Sipapo , affl. río Caura , 07°35′N, 065°25′W . MHNLS 4897 , 1 , Laguna Chirere, ca. 30 km W Puerto Ordaz, río Orinoco floodplain, ca. 08°17′N, 062°59′W (listed in Sullivan & Hopkins, 2009) . MZUSP 96498 , 1 , male, 189 mm, mun. Cedeño, río Parguaza, Puente Parhuena , affl. río Orinoco , 05°53′30″N, 067°24′14″W . SU 54496 , 2 , 97-130 mm , SU 69738 , 2 , 114-126 mm, Caicara, caño de Quiribana, affl. río Orinoco , ca. 07°32′N, 066°08′W . Delta Amacuro (localities from río Orinoco delta, Orinoco dr.). CU 94867, 2, 74-88 mm, Caño Anabeta , Isla Portuguesa, 08°37′N, 061°45′W . MBUCV-V 10660 , 1 , female, 94 mm, Los Castillos , ca. 08°40′N, 062°24′W . Guárico (localities from Orinoco dr.). INHS 34036, 2, 116-118 mm, 20 km ENE La Esperanza, Parque Nacional Aguaro-Guariquito, Morichal Charcote , affl. río Manapire , 08°24′16″N, 066°34′23″W . INHS 34586, 1, 155 mm, N Medano de Gomez, río Guariquito , 07°50′41″N, 066°32′10″W . MBUCV-V 8992 , 1, 115 mm, caño Caracol, on San Fernando de Apure-Guayabal rd. , affl. río Guárico, affl. río Portuguesa, affl. río Apure, 07°58′N, 067°23′W . MBUCV-V 12047 , 1 , immature, 114 mm, caño Realito, affl. río Guariquito , ca. 07°49′N, 066°31′W . MBUCV-V 12068 , 8 (7 immature, 78-100 mm, 1 male, 118 mm), Cabecera del río Guariquito , no coordinates . MHNLS 2021 , 1 , lagoon 30 km N Cabruta , 07°54′N, 066°15′W (listed in Sullivan & Hopkins, 2009) . Monagas. MBUCV-V 1727 , 1 , 90 mm , MBUCV-V 14042 , 1, 110 mm , USNM 233321 , 1, 108 mm, Laguna Guatero, nr. Barrancas, affl. río Orinoco , Orinoco dr., 08°43′N, 062°11′W . MHNLS 6586 , 20 , Laguna San José, Coloradito, río Orinoco delta, Orinoco dr., ca. 08°45′N, 063°29′W (listed in Sullivan & Hopkins, 2009) . Portuguesa. TNHC 14893, 4, 98-134 mm, 35 km SE Guanare, caño (río) Maraca at Urriola Ranch, affl. río Portuguesa, affl. río Apure, Orinoco dr., 08°52′30″N, 069°27′40″W .

Figures

Fig. 19. Brachyhypopomus bullocki. a. MZUSP 96498, male, 188 mm TL (head in lateral view and body in lateral and dorsal view); b. TNHC 17486, female, 140 mm TL (body in lateral view); Venezuela, río Parguaza, Orinoco dr. Specimens fixed in formalin and preserved in EtOH. Scale bars = 5 mm.

Fig. 7. Collection records for Brachyhypopomus arrayae (circles), B. belindae (squares), and B. bullocki (triangles). Holotype locations are marked with open symbols. Elevation data refers to altitude above mean sea level (see Fig. 2 for legend).