Brachyhypopomus belindae, Crampton & de Santana & Waddell & Lovejoy, 2016

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 : 677-679

Brachyhypopomus belindae , new species urn:lsid:zoobank.org:act:B20030E3-840F-409D-841F-A99F658AA8B0

( Figs. 1c , 11 ; Tables 2-5, 7)

Brachyhypopomus sp. “belindae ”. – Crampton et al., 2016: 1-66, table 1, 3-4, figs. 1-7, 18-20 (phylogeny, biogeography and ecology of Brachyhypopomus ).

Holotype. MCP 45360 , immature, 110 mm TL, 92 mm LEA, Brazil, Amazonas , mun. Alvarães , Mamirauá Reserve , lago Araçazinho , rio Solimões-Japurá floodplain, Amazonas dr., 02º59′35″S, 64º51′33″W, 5 Apr 1997, W. Crampton & J. Oliveira.

Paratypes. 5 specimens, localities from Amazonas dr., collected by W. Crampton & J. Oliveira. Brazil. Amazonas (localities listed from Mamirauá Reserve [ Reserva de Desenvolvimento Sustentável Mamirauá ] are in the rio Solimões-Japurá floodplain, mun. Alvarães). INHS 70253 , 1 , 74 mm, lago Murumuru, Janauacá, ca. 42 km SW Manaus, ca. 03°26′S, 060°17′W, 29 Mar 1978 , P. Bayley. MCP 45267 , 1 , immature, 90 mm, Mamirauá Reserve , cano do lago Mamirauá, 03º05′15″S, 064°48′03″W, 18 Jun 1999 . MCP 47867 , 1 , immature, 62 mm, Mamirauá Reserve , cano do lago Rato, 03º02′41″S, 064º51′26″W, Jun 1997 . MCP 45430 , 1 , immature ( CS), 102 mm, Mamirauá Reserve , lago Araçazinho, 02º59′35″S, 064º51′33″W, 15 Jun 1999 . MCP 45431 , 1 , immature, 94 mm, Mamirauá Reserve , cano do lago Mamirauá, 03º06′40″S, 064°47′52″W, 23 Jul 1999 .

Diagnosis. Brachyhypopomus belindae is diagnosed from congeners by the following combination of characters: precaudal vertebrae 24-26, vs. 15-23 in all congeners except B. draco , and B. verdii ; bilateral columns of electrocytes at the anal-fin terminus 4-5 (no mode, median 4.5), vs. 3 in B. draco and B. verdii .

Description. Known only from immature specimens. Head and body shape, and pigmentation illustrated in Figs. 1c and 11 . Meristic and morphometric data for examined specimens presented in Tables 2-5 and 7. Body shallow to moderate in depth. Head short to moderate in length and moderate in depth. Dorsal profile of head straight to slightly convex from occiput to snout, ventral profile of head straight gently convex between operculum and snout, snout rounded. Eye moderate in size. Upper jaw with slight to moderate sigmoidal angle between premaxillary and maxillary portions in lateral view. No accessory electric organ over operculum. Pectoral fin narrow to moderate in width, pectoral-fin rays 15-17 (mode 16). Precaudal vertebrae 24-26 (mode 24) including 1-2 (no mode, median 1.5) transitional vertebrae. Anal-fin origin slightly (<0.25 HL distance) anterior or posterior to, or near, tip of pectoral fin. Anal-fin rays 200-220 (median 209). Dorsal rami of recurrent branch of anterior lateral line nerve not visible. Middorsal region of body scaled. Rows of scales above lateral line 5-6 (mode 6). Lateral line continuous. Sparse groove-like depigmented epidermal canals found mainly in posterior half of the body – as parallel crisscrossing lines either side of lateral line, on flank midway from lateral line to dorsal midline, and as a pair of long irregular lines either side of dorsal surface in dorsal portion of flank. 4-5 bilateral horizontal columns of electrocytes at anal-fin terminus, and at mid-point between anal-fin terminus and tip of caudal filament in immature specimens (mature specimens not available). Caudal filament short to moderate in length.

Coloration. ( Figs. 1c , 11 ). Background tan to light brown. Dorsal region with prominent depigmented pale stripe extending along midline from occipital region to base of caudal filament. Pale middorsal stripe flanked in anterior portion of body by a thin dark horizontally oriented line from which broken or complete lines extend ventrally in a posterior to anterior direction across dorsal and ventral portions of flank to anal-fin margin. Upper flank in anterior portion of body with additional irregular markings. Markings and dark lines less pronounced in posterior portion of body. Caudal filament darker than body, especially dorsally and ventrally. Head with evenly scattered dark chromatophores, darker dorsally. Eye without prominent suborbital patch, or stripe, of chromatophores/subcutaneous pigmentation. 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, with opercular region usually rosy due to underlying gills.

Size. Largest specimen examined 110 mm TL, 92 mm LEA (n = 5).

Sexual dimorphism. Undetermined. Breeding males and females of this species have not yet been collected.

Geographic distribution. Brazil ( Fig. 7 ). Known only from the central Amazon of Brazil; from the type series near Tefé, Amazonas , Brazil, and from a whitewater floodplain site near Manaus .

Ecological notes. A rare species known only from whitewater floodplain habitats. The type series was collected from floating rafts of macrophytes in high conductivity seasonally hypoxic whitewater floodplains at the confluence of the rio Solimões (Amazonas) and rio Japurá. Water parameters recorded at sites near the type locality, through an entire annual flood cycle were typically within the following ranges: 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). Reproductive biology is unknown. Stomach contents of specimens from the type locality comprise aquatic insect larvae and other small aquatic invertebrates ( WGRC unpublished data) .

Co-occurring congeners: Brachyhypopomus belindae is known to co-occur in geographical sympatry and ecological syntopy with the following whitewater floodplain-occurring congeners: B. beebei , B. bennetti , B. brevirostris , B. flavipomus , B. hamiltoni , B. pinnicaudatus , B. regani , and B. walteri . It also exhibits an allotopic distribution with B. batesi , B. hendersoni , and B. sullivani .

Etymology. The specific name is a patronym (noun in the genitive case) in honor of Belinda Siew-Woon Chang, American ( USA) evolutionary biologist, for her inspiration to NRL during the preparation of this work.

Local names. Brazil: sarapó.

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. 11. Brachyhypopomus belindae. MCP 45360 (WC05.050497), holotype, immature, 110 mm TL (head in lateral view, body in lateral and dorsal views, specimen fixed in formalin and preserved in EtOH); Brazil, rio Solimões-Japurá confluence, Amazonas dr. 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).