Bryconops piracolina, Wingert & Malabarba, 2011

Wingert, Juliana M. & Malabarba, Luiz R., 2011, A new species of Bryconops (Teleostei: Characidae) from the rio Madeira basin, Northern Brazil, Neotropical Ichthyology 9 (3), pp. 471-476 : 472-474

Bryconops piracolina , new species

Figs. 1-4

Holotype. MCP 44796, male, 69.0 mm SL, Brazil, Rondônia, Vilhena, Igarapé Piracolina ( rio Madeira basin), about 6 km W of Vilhena, near highway BR-364, 12°43’33”S 60°11’34”W, 14 Jul 2004, R. E. Reis, P. A. Buckup, A. R. Cardoso & E. H. L. Pereira . Paratypes. Brazil: Rondônia: MCP 41504, 1 male (c&s, 51.1 mm SL), 4 females (1 c&s, 35.0 mm SL), 29.3-71.3 mm SL , MZUSP 105731 , 2 females (32.9 and 40.1 mm SL), collected with holotype .

Diagnosis. Bryconops piracolina belongs to the subgenus Bryconops in having no teeth or rarely one tooth on the maxilla and a naked area on the cheek between the second and third infraorbitals. It is distinguished from all species of this subgenus by the pigmentation of the dorsal fin with a large black blotch extending from near the dorsal-fin base distally for approximately one half the length of most dorsal-fin rays, in contrast to the dorsal fins of congeneres that are slightly pigmented with scattered chromatophores. Bryconops piracolina furthermore is distinguished from all congeners, except B. inpai Knöppel, Junk & Géry, 1968 , by possessing an entirely black adipose fin. It differs from B. inpai by its lack of humeral spots. It further differs from all species of the subgenus Bryconops , except for B. caudomaculatus (Günther, 1864) , by having the last scales of the longitudinal series of scales that bears the lateral line series not pored beyond the end of the hypural plate. Bryconops piracolina differs from B. caudomaculatus by the number of pored lateral line scales (31-36, mean 34.6, n = 8, vs. 37-43, mean = 40.6, n = 101, respectively).

Description. Morphometric data summarized in Table 1. Largest specimen 71.3 mm SL. Body shape compressed, greatest body depth located just anterior to dorsal-fin origin. Dorsal body profile convex from margin of upper lip to region near nares; straight from that point to end of supraoccipital spine; convex from this point to dorsal-fin origin. Straight and posteroventrally-aligned along dorsal-fin base; straight and convex from end of dorsal-fin base to adipose fin and concave from that point to insertion of dorsal procurrent caudal-fin rays. Ventral body profile convex from lower jaw to pelvic-fin origin; straight from this point to anal-fin origin. Straight and posterodorsally-aligned along anal-fin base; concave from posterior end of anal-fin base to ventral procurrent caudal-fin rays. Caudal peduncle slightly longer than deep. Dorsal-fin origin situated anterior to vertical through pelvic-fin origin and near middle of body.

Cheek area between second and third infraorbitals naked ventrally; third infraorbital moderately developed, not reaching preopercle ventrally or at angle. Supraorbital bone present. Eyes large than shout length. Adipose ocular membrane well developed. Maxilla not extending posteriorly to posterior margin of second infraorbital ( Fig. 2 ) and not reaching vertical through middle of orbit. Mouth terminal, premaxilla slightly longer than lower jaw. Premaxilla with two tooth rows, with central cusp of all teeth more developed than remaining cusps; outer row with 3(2) or 4(6) tricuspid teeth; inner row 5 teeth with 3 to 5 cusps. Maxilla with 0(7) or 1(1) tricuspid teeth. Dentary with 4 large teeth with 5 to 7 cusps, followed by 4 smaller conical teeth ( Fig. 3 ).

Dorsal-fin rays ii,9*(8). Posterior margin of dorsal-fin straight to slightly convex, with first and second branched rays longest. Length of first unbranched dorsal-fin ray less than half length of second unbranched ray. Adipose-fin origin approximately at vertical through base of nineteenth to twenty-first anal-fin branched rays. Pectoral-fin rays i,10(3), 11*(4), or 12(1). Tip of pectoral fin not reaching pelvic-fin origin. Pelvic-fin rays: i,7*(8). Pelvic fin originating at vertical through middle of dorsal-fin base, reaching and sometimes extending beyond anal-fin origin. Anal-fin rays iv-v,21(3), 22(2), 23(2), or 24*(1), first unbranched ray sometimes visible only in cleared and stained specimens.Anal-fin origin located posterior to vertical through base of last dorsal-fin ray. Distal margin of anal-fin falcate in juveniles with last unbranched ray and second and third branched rays slightly longer than others, but nearly straight in adults. Caudal-fin rays i,8,9,i principal rays (8). Lobes of caudal fin unequal with lower lobe longer than upper lobe. Dorsal procurrent caudal-fin rays 11, ventral procurrent caudal-fin rays 11.

Total scales in longitudinal series containing lateral line scales 38(2), 39(1), 40*(1), 41(1), or 42(2). Pored lateral line scales 31(1), 34(2), 35*(2), or 36(3). Scale rows between lateral line and dorsal-fin origin 6(2) or 7*(6). Scale rows between lateral line and pelvic-fin origin 5*(7). Predorsal scales 8(1) or 9*(6) and arranged in regular series. Scale rows around caudal peduncle 10*(4) or 11(3). Scales along anal fin base 3 or 4 in single series. Few scales covering base of caudal-fin lobes. Precaudal vertebrae 18*(2); caudal vertebrae 22(1), 24(1); total vertebrae 40(1), 42(1). First dorsal-fin pterygiophore located between tenth and eleventh vertebrae. Supraneurals 7(2), large, inserted between neural spines.

Gill rakers of first gill arch 14 or 15: hypobranchial 2(2), ceratobranchial 6(2), between epibranchial cartilage and ceratobranchial 1(2), epibranchial 5(1), 6(1). Branchiostegal rays 4: 3(2) on ceratohyal and 1(2) on epihyal. Gill rakers setiform.

Color in alcohol. Overall ground coloration of body dusky brown. Dorsal profile of head, snout, and upper jaw with scattered black chromatophores. Opercle with chromatophores scattered over dorsolateral region. Infraorbitals, opercular and gular regions pale yellow. Heavily pigmented black mid lateral stripe extending from upper margin of opercle to caudal-fin base. Stripe narrow anteriorly and progressively expanding from head to under dorsal fin; occupying almost half distance between lateral line and dorsal contour of body in region between dorsal and adipose fins and then becoming narrower along caudal peduncle. Scales on dorsal and dorsolateral portions of body with black chromatophores more concentrated on their edges. Scales dusky with chromatophores less concentrated ventrally. Pored lateral-line scales slightly more pigmented than surrounding scales, resulting on lateral line being readily visible posteriorly to vertical trough posterior portion of dorsal fin and in some specimens, almost to posterior limit of lateral line. No humeral blotch. Many black chromatophores scattered on portion of body between lateral line and anal-fin base. Dorsal fin with black blotch extending from near dorsal-fin base to mid length of dorsal-fin rays; distal margin of dorsal fin lighter. Adipose fin black. Anal, pectoral and pelvic fins with scattered black chromatophores. Caudal fin rather dark, with small more lightly pigmented areas near base of dorsal and ventral lobes. Upper lobe of caudal fin with darkened proximal blotch reaching dorsal border of fin ( Fig. 1 ).

Sexual dimorphism. Males bear hooks on the anal and pelvicfin rays. Anal-fin hooks are small and spine-like and distributed along only the distal half of the fin rays up to the eleventh the branched ray. Number of hooks decreasing from last unbranched ray to eleventh branched ray ( Fig. 4 ). Pelvicfin hooks larger and spine-like; present on unbranched ray and first five branched rays.

Distribution. Bryconops piracolina is known from its type locality, Igarapé Piracolina, a tributary to the rio Madeira, rio Amazonas drainage, about 6 km west of Vilhena, Rondônia, Brazil ( Fig. 5 ).

Etymology. The specific epithet name piracolina is given in allusion to its type locality, Igarapé Piracolina. A noun in apposition.

Figures

Fig. 1. Bryconops piracolina, MCP 44796, holotype, male, 69.0 mm SL; Brazil, Rondônia, Igarapé Piracolina, tributary of rio Madeira, rio Amazonas drainage, about 6 km West of Vilhena.

Fig. 2. Maxilla and infraorbitals 1-5 of Bryconops piracolina, right side, MCP 41504, paratype, 35.0 mm SL, c&s. Abreviations: I-1 to I-5= Infraorbitals 1 to 5; MA= maxilla. Scale bar = 1 mm.

Fig. 3. Bryconops piracolina, MCP 41504, paratype, 51.11 mm SL c&s. Scanning electron microscope photograph of left side of maxilla (top), premaxilla (middle), and lower jaw (bottom). Dorsal portion of dentary partially broken.

Fig. 4. Anal-fin rays of Bryconops piracolina, male, MCP 41504, paratype, 51.11 mm SL, c&s. Left side, anterior to left. Small hooks on the anal fin present only on the distal half of the last unbranched ray up to the eleventh branched anal-fin ray. Scale bar = 1 mm.

Fig. 5. Central and Northern South America, showing the collection site of Bryconops piracolina, in the rio Madeira drainage.