Brachyhypopomus cunia, 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 : 706-708

Brachyhypopomus cunia , new species urn:lsid:zoobank.org:act:E9E6020F-21D4-42B5-8F2D-0F1A1D4E8645

( Fig. 20 ; Tables 2-5, 8)

Brachyhypopomus sp. 3 . -Crampton & Ribeiro, 2013: 240, color photograph ( Brazil, rio Madeira, listing of hypopomids). -de Queiroz et al., 2013: 545, table 1 ( Brazil, rio Madeira, lago Cuniã, listing of fish species).

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

Holotype. INPA 37690 , male, 142 mm TL, 104 mm LEA, Brazil, Rondônia, Reserva Extrativista do lago do Cuniã, igarapé do Campo , affl. lago Cuniã , rio Madeira floodplain, Amazonas dr., 08°19′14″S, 063°28′05″W, 1 Dec 2008, T. Araújo & F. Vieira.

Paratypes. 40 specimens, localities from rio Madeira dr., Amazonas dr. Brazil . Rondônia. INPA 37691 , 4 (1 immature, 124 mm, 3 female [1 CS], 113-121 mm), MPEG 24297, 10, 99-137 mm, UFRO-I 1323, 3, 80-125 mm, collected with holotype. MCP 46939 , 10 (7 immature, 87- 149 mm, 3 female, 126-136 mm), MZUSP 110994 , 5 (1 immature, 90 mm, 2 female, 114-141 mm, 1 male, 117 mm), UFRO-I 6398, 1, female, 116 mm, UFRO-I 6399, 1, female, 119 mm, UFRO-I 6400, 1, immature, 112 mm, UFRO-I 6401, 1, immature, 128 mm, UFRO-I 6402, 1, immature, 144 mm, UFRO-I 7928, 4 (2 immature, 107-139 mm, 1 female, 118 mm, 1 male, 154 mm), mun. Porto Velho , lago Cuniã, rio Madeira floodplain, 08°19′S, 063°28′W, 6 Jun 2010, T. Araújo & F. Vieira .

Non-types. 216 specimens, localities from rio Madeira dr., Amazonas dr. Brazil . Mato Grosso. FMNH 54552, 7, 48- 112 mm, Bastos [Porto Bastos], rio Alegre, affl. rio Guaporé , affl. rio Mamoré , ca. 15°06′S, 059°57′W . USNM 301979 , 3 , 83-135 mm, Brazil-Bolivia border, region between Guajará-Mirim and Mato Grosso, rio Guaporé, affl. rio Mamoré , ca. 13°42′S, 060°31′W . Rondônia. MCP 46937 , 3 (2 CS), 92- 118 mm, mun. Calamã, nr. Calamã, rio Madeira floodplain lake, 08º01′37″S, 062°52′28″W . UFRO-I 6467, 4,75-95 mm, Colocação Três Praias, rio Jaciparaná , 09°27′29″S, 064°25′22″W . UFRO-I 6470, 14, 95-146 mm, lago Cuniã , 08°21′10″S, 063°30′26″W . UFRO-I 6471, 2, 130-147 mm, lago Cuniã , 08°19′45″S, 063°28′06″W . UFRO-I 6474, 14, 128-176 mm, UFRO-I 6475, 2, 143-148 mm, lago Cuniã, 08°19′36″S, 063°29′59″W. UFRO-I 6477, 25, 147-165 mm, mouth of rio Cautário, affl. rio Guaporé, affl. rio Mamoré , 12°10′51″S, 064°34′00″W . UFRO-I 6479, 74, 80-152 mm, nr. igarapé do Campo, lago Cuniã , 08°19′09″S, 063°28′44″W . UFRO-I 6514, 68, 67-150 mm, nr. ICMBio base, lago Cuniã , 08°19′40″S, 063°30′11″W .

Diagnosis. Brachyhypopomus cunia is diagnosed from congeners by the following combination of characters: precaudal vertebrae 16-17, vs. 18-26 in B. alberti , B. arrayae , B. beebei , B. belindae , B. brevirostris , B. draco , B. flavipomus , B. gauderio , B. hamiltoni , B. janeiroensis , B. jureiae , B. palenque , B. pinnicaudatus , and B. verdii ; head depth at eye 47.8-60.0% HL, vs. 36.3-47.7% in B. batesi , B. bombilla , B. provenzanoi , B. regani , and B. sullivani ; scales present in middorsal region of anterior third of body, vs. absent in B. benjamini ; pectoral-fin rays 10-13, vs. 14-20 in B. bennetti , B. diazi , B. menezesi , and B. occidentalis ; mouth width 24.8- 38.0% HL, vs. 15.7-22.6% in B. hendersoni . Brachyhypopomus cunia exhibits overlapping meristic counts and morphological measurements with B. bullocki and B. walteri , but differs in possessing a very distinctive pigmentation pattern in which the ventral portions of the flank, over the anal-fin pterygiophores, are darkly pigmented, forming a dark stripe along the base of the anal fin (also shared with B. hendersoni ), and in possessing numerous discrete dark spots (each comprising a cluster of dark chromatophores) which are scattered over the anal-fin pterygiophores, and in some specimens form an irregular dotted line along the lateral line, vs. absence of dark stripe along the anal-fin base and absence of discrete dark spots over the ventral flank in B. bullocki and B. walteri .

Description. Head and body shape, and pigmentation illustrated in Fig. 20 . 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 slightly to moderately convex from occiput to snout, ventral profile of head approximately straight to slightly convex between operculum and snout, snout rounded. Eye moderate to large in size. Upper jaw with 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 10-13 (mode 12). Precaudal vertebrae 16-17 (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 177-224 (median 209). Dorsal rami of recurrent branch of anterior lateral line nerve visible in anterior third of body in most specimens. Middorsal region of body scaled. Rows of scales above lateral line 5-7 (mode 6). Lateral line continuous. Sparse depigmented epidermal canals in posterior two thirds of body; present as a meandering and bifurcating single groove in dorsal flank, approximately midway from lateral line to dorsal midline; and as sparse scratch-like marks dorsal to and near lateral line, sometimes connecting to a longer canal in dorsal flank. Three 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. Caudal filament moderate in length to long.

Coloration. ( Fig. 20 ). Background tan to light brown. Dorsal region without prominent depigmented pale stripe extending along midline from occipital region to base of caudal filament. Dorsal surface with irregular patches and vague thin bands; few or none crossing entire dorsal surface, some forming faint oblique bands from dorsal surface to near lateral line which slant in an anteroventral to dorsoposterior direction. No bands on ventral surfaces of flank. Prominent dark flecks scattered over flank and anal-fin pterygiophores, and forming an irregular dotted line along lateral line. Ventral flank over anal-fin pterygiophores, especially in ventral half along anal-fin base with darker background pigmentation forming a dark horizontal band along anal-fin margin (more conspicuous in some specimens than others). Caudal filament darker than body, especially distally; darkened tip of caudal filament resembles root tips of water hyacinths when viewed underwater. Eye always with distinct suborbital patch or stripe of chromatophores and subcutaneous pigmentation. Pectoral and anal-fin membranes hyaline. Pectoral-fin rays and anal-fin rays with light scattering of brown chromatophores. Color in live individuals similar to preserved specimens, with opercular region usually rosy due to underlying gills.

Size. Moderate size, largest specimen examined 176 mm TL, 121 mm LEA (n = 257). Largest male specimen examined 154 mm TL, 103 mm LEA (n = 3). Largest female specimen examined 141 mm TL, 102 mm LEA (n = 11).

Sexualdimorphism. Noknownsecondarysexualdimorphism.

Geographic distribution. Brazil ( Fig. 14 ). Known only from the rio Madeira; from its lower reaches below its major series of falls and rapids as far downstream as a site near the town of Calamã, Rondônia, Brazil (near the mouth of the rio Machado), and from sites above the major series of falls, along most of the length of the rio Guaporé. Not known from lower reaches of the Madeira downstream of its confluence with the rio Machado.

Ecological notes. Known from low-conductivity floodplain habitats. The type series was collected from floating macrophytes on the margins of lago Cuniã, a low-conductivity seasonally flooded blackwater lake near the main stem of the lower Madeira. Here the flood season occurs between October and March, and the low-water season from April to September (de Queiroz et al., 2013). Water parameters collected from November 2008 to March 2010 are typical of a lowland blackwater lake: conductivity 2.3-11.2 µScm- 1, transparency measured with a Secchi disk 0.35-2.69 m, dissolved oxygen 2.2-5.8 mgl-1, temperature 27.1-31.3°C, and pH 4.52-6.88 (de Queiroz et al., 2013). Brachyhypopomus cunia is also common from low-conductivity clearwater (and some blackwater) floodplain sites along most of the length of the rio Guaporé. Mean water parameters, averaged from multiple sites along the rio Guaporé, and over several seasons, include: conductivity 19.5 µScm-1 (SD 16.79), transparency with Secchi disk 1.04 m (SD 0.44), dissolved oxygen 4.22 mgl-1 (SD 1.98), temperature 27.5°C (SD 2.44), and pH 7.12 (SD 1.06) (L. de Queiroz, unpublished data). 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: Above the major series of rapids and falls in the lower Madeira, Brachyhypopomus cunia co-occurs in geographical sympatry with the following congeners: B. alberti , B. arrayae , B. bombilla , B. brevirostris , B. pinnicaudatus , B. sullivani , and B. walteri . Below the lower Madeira rapids, Brachyhypopomus cunia is known to occur in sympatry and ecological syntopy with B. brevirostris , B. pinnicaudatus , and B. walteri (de Queiroz et al., 2013) .

Etymology. The specific name refers to the type locality, lago Cuniã, a floodplain lake of the lower rio Madeira inside the Reserva Extrativista do lago do Cuniã. A noun in apposition.

Local names. Brazil: sarapó.

Figures

Fig. 20. Brachyhypopomus cunia. INPA 37690, holotype, male, 142 mm TL (head in lateral view and body in lateral and dorsal view); Brazil, rio Madeira, Amazonas dr. Specimen fixed in formalin and preserved in EtOH. 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).