Bryconops sapezal, Wingert & Chuctaya & Malabarba, 2018

Wingert, Juliana M., Chuctaya, Junior & Malabarba, Luiz R., 2018, A new species of Bryconops (Characiformes: Iguanodectidae) from the Rio Tapajós basin, Brazil, Zootaxa 4418 (4), pp. 379-387 : 380-385

Bryconops sapezal new species

( Figs. 1–6 )

Holotype. MCP 44795, female, 91.2 mm SL, Brazil, Mato Grosso, Sapezal, Rio Sauê-Uiná downstream from a dam, near the highway BR-364, Rio Tapajós basin, 13°32'22"S 58°50'48"W, P.C. Lehmann, V.A. Bertaco, J.F. Pezzi da Silva & F. Langeani, 13 Jul 2004.

Paratypes. All from Brazil, Amazonas: MCP 41502, 21, 29.3 – 90.7 mm SL (2 females c&s, 31.9 – 79.6 mm SL; 1 male, 71.5 mm SL), and MZUSP 123161, 5, 29.32 – 90.67 mm SL, collected with holotype . MCP 45999, 10, 38.5 – 50.1 mm SL (1 female c&s, 42.3 mm SL), São José do Rio Claro, Rio Claro or Rio Água Verde near highway MT-010, about 12 km southeast of São José do Rio Claro , 13°30'12"S 56°37'08"W, R.E. Reis, L.R. Malabarba, E.H.L. Pereira, V.A. Bertaco & A.R. Cardoso, 17 Jan 2002 . MCP 46003, 11, 42.7 – 66.6 mm SL, (1 female c&s, 45.4 mm SL), São José do Rio Claro, stream on the highway MT-338, about 46 km north of Tapurah , 12°23'14"S 56°41'54"W, R.E. Reis, L.R. Malabarba, E.H.L. Pereira, V.A. Bertaco & A.R. Cardoso, 19 Jan 2002 . MCP 46000, 6, 24.7 – 86.4 mm SL (1 female c&s, 41. 8 mm SL), São José do Rio Claro, stream on the road to Nova Maringá about 4 km northwest of São José do Rio Claro , 13°25'51"S 56°44'53"W, R.E. Reis, L.R. Malabarba, E.H.L. Pereira, V.A. Bertaco & A.R. Cardoso, 18 Jan 2002 . MCP 46001, 10 , 49.1 -68.0 mm SL (1 female c&s, 49.1 mm SL; 1 male, 55.5 mm SL), Tapurah, stream on the highway MT-338 about 33 km North of Tapurah , 12°29'46"S 56°40'43"W, R.E. Reis, L.R. Malabarba, E.H.L. Pereira, V.A. Bertaco & A.R. Cardoso, 19 Jan 2002 . MCP 46002, 3 , 54.0 – 75.1 mm SL, Diamantino , córrego Caju, Caju, 14°21'47"S 56°24'30"W, R.E. Reis, L.R. Malabarba, E.H.L. Pereira, V.A. Bertaco & A.R. Cardoso, 17 Jan 2002 . LIRP 7645 , 8 of 11, 40.6 – 77.0 mm SL, Sapezal, Rio Juruena , 12°54'22"S 58°55'01"W, R.J. Ilário, 11 Jan 2010.

Diagnosis. Bryconops sapezal differs from all species of the genus by the color pattern of the caudal fin, which consists of the dorsal lobe conspicuously dark pigmented on its distal half and the ventral lobe dark gray pigmented along its ventral portion below horizontal through ventral margin of caudal peduncle. It further differs from the species of the subgenus Bryconops by presenting the maxillary bone elongated, reaching near the contact between the second and third infraorbital bones (vs. not reaching), and absence of a naked area between second and third infraorbital (vs. presence). It differs from the species of the subgenus Creatochanes by the lack of a humeral blotch (vs. humeral blotch present in B. humeralis , B. inpai , B. munduruku , and B. vibex ); absence of caudal fin ocellus (vs. caudal fin with almost symmetric conspicuous ocelli on both lobes in B. affinis , and caudal fin with a single conspicuous ocellus on the dorsal lobe in B. giacopinii and B. transitoria ); by presenting caudal-fin densely pigmented, more conspicuously in dorsal lobe, not forming band (vs. prominent black stripe, extending from the middle caudal fin rays to the lower upper lobe caudal fin rays in B. melanurus ; caudal fin with melanophores along rays proximally, becoming darker posteriorly forming a distinct dark marginal band in B. imitator ; caudal fin entirely black with some sparse red pigmentation in the upper and lower lobes in B. colanegra ); and caudal fin red at proximal portions of upper and lower lobes, dark gray in the distal portion of upper lobe and light gray in the distal portion of the lower lobe (vs. caudal fin almost entirely red in B. colaroja ).

Description. Morphometric data are presented in Table 1. Largest specimen 91.2 mm SL. Body slender and elongate, greatest body depth at dorsal-fin origin corresponding to most elevated point in dorsal profile. Dorsal body profile slightly convex from upper lip to dorsal-fin origin; slightly convex along dorsal-fin base; straight from dorsal-fin terminus to adipose-fin origin, becoming concave from that point to origin of dorsal procurrent caudalfin rays. Ventral body profile convex from lower jaw to pelvic-fin origin; convex from that point to anal-fin origin; straight along anal-fin base; concave from anal-fin terminus to ventral procurrent caudal-fin rays. Caudal peduncle relatively longer than deep. Dorsal-fin origin at vertical through pelvic-fin origin, near midbody.

Head relatively small. Border between second and third infraorbitals without naked area; third infraorbital greatest, not reaching ridge of preopercle or angle. Supraorbital bone present. Eyes large. Adipose eye-lid present. Maxilla large, reaching posterior margin of second infraorbital ( Fig.2 ). Mouth terminal, lower jaw longer than upper jaw. Premaxilla with two tooth rows; central cusp in all teeth more developed than remaining cusps; outer row with 2*(6), 3(35) or 4(11) teeth tri- to pentacuspid; inner row 3(1), 4(15), 5*(35) or 6(1), pentacuspid teeth. Posterior tip of maxilla surpassing vertical through middle of orbit. Maxilla without teeth (4), or with 1(10), 2*(33) or 3(5) teeth, with 3 to 5 cusps. Dentary with 5 to 6 large teeth, bearing 5 to 7 cusps, followed by 10 smaller conical teeth ( Fig. 3 ).

Dorsal-fin rays ii*(52), 9*(52). Posterior margin of dorsal fin straight, with first branched ray longest. Length of first unbranched dorsal-fin ray less than half of second unbranched ray. Adipose-fin origin approximately at vertical through insertion of last anal-fin rays. Pectoral-fin rays i,11*(25) or i,12(27). Pectoral fin not reaching pelvic-fin origin in males and females. Small sized specimens (29.3 – 57.7 mm SL) with large pectoral fins, not reaching pelvic-fin origin. Pelvic-fin rays i,6(1), i,7*(51). Pelvic-fin origin approximately at vertical through dorsal-fin origin. Pelvic fin reaching and, in some individuals, surpassing anal-fin origin in smaller specimens (29.3–57.7 mm SL), not reaching anal fin in larger specimens. Anal-fin rays iv, 21(1), 23(6), 24(15), 25*(18) or 26(11). Anal-fin origin posterior to dorsal-fin base. Caudal-fin rays i,9*(52) on upper lobe, and i,8*(52) on lower lobe. Caudal fin forked, lower lobe slightly longer than upper lobe or similar in size. Dorsal procurrent caudal-fin rays 14. Ventral procurrent caudal-fin rays 12. First procurrent ray small, wide and slightly branched.

Scales cycloid, lateral line series with 42(1), 44(2), 45(8), 46(7), 47*(17), 48(8), 49(2) or 50(2) scales, of which 40(1), 42(2), 43(8), 44*(16), 45(13), 46(2), 47(3) or 48(2) perforated; rows between lateral line and dorsalfin origin 7*(42) or 8(5); rows between lateral line and pelvic-fin origin 3(1) or 4*(46). Predorsal scales 9(2), 10(11), 11*(23) or 12(11) in regular series. Circumpeduncular scales 10(4), 11*(34), 12(4) or 13(5). Scales covering base of proximal lobes of caudal-fin. Precaudal vertebrae 18(1), 19*(5) or 20(1); caudal vertebrae 22(1), 23(3) or 24(3); total vertebrae 41 to 44. Proximal tip of first dorsal-fin pterygiophore inserted between neural spine of 11th and 12th vertebrae. Supraneurals 7(7), equal in length and thickness, ventrally reaching beyond tip of neural spines.

Gill rakers 17 to 18: epibranchial 7(2), ceratobranchial 9(1) or 10(1), between epibranchial cartilage and ceratobranchial 1(1), hypobranchial 3(2). Branchiostegal rays 4(2): 3(2) on anterior ceratohyal and 1(2) on epihyal. Gill rakers setiform thin and relatively long, increasing progressively in size from first gill raker of epibranchial to approximately end of ceratobranchial, decreasing in size in hypobranchial with spines.

Color in alcohol. General ground body color light yellow below and dark brown above longitudinal stripe.

Dorsal portion of head, snout, upper jaw and maxilla with several dark gray chromatophores. Dorsolateral region of opercle with scattered dark gray chromatophores. Infraorbitals, opercular and gular regions pale yellow. Scales on dorsal and dorsolateral areas of the body with dark gray chromatophores, more concentrated in the center of the scales. Humeral blotch absent. Lateral stripe dark pigmented from dorsal border of opercle to caudal-fin base; narrow anteriorly, becoming progressively wider to vertical through dorsal-fin terminus; between that point and caudal-fin base occupying at least one third of the lateral surface of the body. Portion between anal fin and lateral line with dark line of equal length of anal-fin base. Anal, pectoral and pelvic fins scattered with dark gray chromatophores. Dorsal fin slightly dark pigmented. Adipose fin slightly pigmented. Dorsal lobe of caudal fin densely dark pigmented on distal half; ventral lobe slightly dark pigmented along its ventral portion below horizontal through ventral margin of caudal peduncle. Proximal portion of the upper and lower lobes light beige, lighter area broader on the upper lobe.

Color in life. Body dark gray dorsally. Head and body silvery bluish laterally and whitish ventrally. Iris yellow, dark gray dorsally and whitish ventrally. Lower jaw dark yellow to black. Dorsal fin intense red and adipose fin yellow. Basal region of the anterior half-portion of anal fin orange to red, the remaining fin translucent. Pectoral fin translucent. Pelvic fin with a red pigmentation at its base. Caudal fin red from its base to half-length of upper and lower lobes; dark gray in the distal portion of the upper lobe and light gray in the distal portion of the lower lobe ( Fig. 4 ).

Sexual dimorphism. Males bear hooks on anal and pelvic-fin rays ( Fig. 5 ). Hooks are found along all anal-fin rays, from the most basal segment of the fin ray to its distal portion, small and spine-like in the first three branched rays, and larger, numerous, and hook-shape between 4th and 20th anal-fin rays. Pelvic-fin hooks larger than those of anal fin, present on the six lateralmost branched rays. In females, the last unbranched ray, and the second to fourth branched rays are slightly longer than remaining rays, forming a slightly falcate anterior anal-fin lobe. In males, the anterior lobe formed by the same fin rays is slightly rounded in shape.

Distribution. Bryconops sapezal is known from the upper Rio Juruena drainage, rio Tapajós basin, Mato Grosso, Brazil ( Fig. 6 ).

Conservation status. According to IUCN (2017) criteria, Bryconops sapezal has a large area of occurrence in the upper Rio Juruena and is considered not threatened.

Etymology. The epithet " sapezal " is given in allusion to its type locality, the Sapezal municipality, and means covered with sapê ( Imperata brasiliensis , Poaceae ).

Figures

FIGURE 1. Bryconops sapezal, MCP 44795, holotype, female, 91.2 mm SL; Brazil, Mato Grosso, Sapezal, Rio Sauê-Uiná downstream from a dam near the BR-364.

FIGURE2. Maxillaand infraorbital bones of Bryconops sapezal, right side, MCP 41502, paratype,31.9 mm SL.Scale bar = 1 mm. Abbreviations: I-1 to I-6= infraorbitals; MA= maxilla.

FIGURE 3. Bryconops sapezal, MCP 41502, paratype, 79.6 mm SL. Scanning electron microscope photograph of left side of maxilla (top), premaxilla (middle), and dentary (bottom).

FIGURE 4. Coloration in life of Bryconops sapezal. Rio Juruena, Rio Tapajós basin, Mato Grosso State, Brazil. Photo: Rodrigo J. Ilário.Scale bar = 10 mm.

FIGURE 5. Anal-fin rays of Bryconops sapezal, male, MCP 41502, paratype, 71.4 mm SL c&s. Left side. Scale bar = 1 mm.

FIGURE 6. Map of the Amazon basin, showing the distribution of Bryconops sapezal in the Rio Tapajós drainage. Symbols may represent more than one collection event. Red star represents the type locality.