Brycon coxeyi Fowler 1943
Creators: name: Lima, Flávio C. T.
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Actinopterygii
Characiformes
Bryconidae
Brycon
Brycon coxeyi

description: Brycon coxeyi Fowler, 1943
(Figs. 11–15)
Brycon atricaudatus (sic) (non Kner & Steindachner, 1863): Boulenger, 1898a: 3 (part; Ecuador, “ Rio Zamora”). Brycon oligolepis (non Regan): Tortonese, 1939: 49 (Ecuador, “ Rio Zamora”; same specimen examined by Boulenger, 1898a). Brycon coxeyi Fowler, 1943: 3 –4, fig.2 (Type locality, “Hacienda La Mascota, mouth of the Rio Pastaza, basin of the Rio
Marañon, Ecuador”). Lima, 2003: 175–176 (correction of type locality to “ Ecuador, Napo-Paztaza, Hacienda Mascota, Río
Topo, a tributary of Río Paztaza, 1°25’S, 78°11’W ”).
? Brycon species: Géry, 1972b: 7 –8 (Río Villano, tributary of Río Cururay, Amazon basin).
Diagnosis. Brycon coxeyi can be distinguished from all remaining cis-andean Brycon species, except Brycon stolzmanni, by possessing a distinct patch of dark pigmentation on the opercle (vs. patch of dark pigmentation on the opercle absent in the remaining cis-andean Brycon species) and infraorbital series not closed, with the orbital margin partially delimited by the frontal bone (vs. infraorbital series closed, frontal excluded from the orbital series by the contact between the supraorbital and the sixth infraorbital bone). Brycon coxeyi can be distinguished from Brycon stolzmanni by possessing the dark patch of pigmentation on opercle well-defined, typically lying at its center (vs. dark patch of pigmentation diffuse and restricted to the upper half of opercle in B. stolzmanni).
Description. Morphometric data are presented in Table 2. Relatively small-sized species, largest examined specimen 225.0 mm SL. Body moderately high. Largest body height slightly ahead of dorsal-fin origin. Dorsal body profile slightly convex from upper lip margin to vertical through anterior naris, slightly concave from latter point to basis of supraoccipital process, and moderately convex from latter point to dorsal-fin origin, straight along dorsal-fin basis, straight to slightly convex from dorsal-fin terminus to adipose-fin origin. Dorsal profile of caudal peduncle slightly concave. Ventral profile slightly convex from lower lip to pelvic-fin insertion, straight to slightly convex from this point to anal-fin origin and approximately straight along anal-fin base. Ventral profile of caudal peduncle slightly concave.
Head profile slightly acute anteriorly, mouth terminal, jaws approximately isognathous. Maxillary extending posteriorly to vertical slightly anterior to middle of pupil. Adipose eyelid well developed. Premaxillary teeth in three rows; teeth of third row largest. Five (2), 6 (24), 7 (25), 8(5), or 9(1) tricuspidate teeth in outer series. Two (4), 3 (42), or 4 (7) tri- to tetracuspidate teeth in second, inner premaxillary row, plus 2 (4), 3 (42), or 4(7) tricuspidate teeth between the first and third rows. Two teeth in third premaxillary row, medial teeth largest, symphyseal teeth smaller, both pentacuspidate. Maxillary with distal portion expanded and rounded in profile. Nine to 21 maxillary teeth, slightly smaller than teeth of first premaxillary row, anterior teeth tricuspidate, posterior teeth unicuspidate. Dentary with 6(2), 7(1), 9(1), 11 (1), or 13 (1) teeth in main series. Anterior four dentary teeth assymetrical, considerably larger and bulkier than remaining teeth, tetra- to pentacuspidate, each with central cusp distinctly larger than remaining cusps. Remaining dentary teeth progressivelly smaller, tri- to unicuspidate. Inner (lingual) series consisting of a single unicuspid symphyseal tooth, considerably smaller than teeth of main series anterior to it, plus row of 6 small, unicuspidate teeth, originating behind last tooth of the main series.
Scales cycloid. Lateral line complete, from supracleithrum to caudal-fin base. Forty-two (1), 43 (1), 44(3), 45 (15), 46 (17), 47 (8), 48 (9), 49 (2), 50 (1), or 52 (1) scales in lateral line series; laterosensory tube simple, straight or slightly deflected downwards. Horizontal scale rows between dorsal-fin origin and lateral line 8 (22), 9 (34), or 10 (2). Horizontal scale rows between lateral line and pelvic-fin 4 (9), 5(43), or 6(5). Circumpeduncular scales 14 (4), 15 (4), 16 (30), 17 (16), 18 (1), or 19 (1).
Dorsal-fin rays ii, 9, one specimen ii, 10. Dorsal fin origin at middle of SL. Dorsal fin displaying numerous (c. 15–30 per fin-ray main branch) small hooks on last unbranched and all branches (more numerous on last branch) of all branched rays in 13 specimens (MEPN 11101, 205.0 mm SL; MEPN 11108, 155.4 mm SL; MEPN 11115, 144.8 mm SL; MEPN 11109, 150.9 mm SL; MEPN 11103, 187.0 mm SL; MEPN 11105, 168.1 mm SL; MEPN 11114, 2, 153.0– 157.2 mm SL; MEPN 11112, 122.6 mm SL; MUSM 6127, 2, 126.6– 135.4 mm SL; MUSM 6136, 2, 131.5– 135.8 mm SL). Anal-fin rays iii (not including first, small unbranched ray only visible in the cs specimen), 21 (6), 22 (17), 23 (33), or 24 (10). Last unbranched and anterior 2–3 branched anal-fin rays longer, remaining rays progressively shorter towards anal-fin end. Anal fin displaying numerous (c. 20–30 per fin-ray main branch) small hooks associated with dense, gelatinous tissue on last unbranched and posterior main branch of all branched rays except posteriomost ray in 15 specimens (MEPN 11101, 205.0 mm SL; MEPN 11108, 155.4 mm SL; MEPN 11115, 144.8 mm SL; MEPN 11109, 2, 149.6– 150.9 mm SL; MEPN 11103, 187.0 mm SL; MEPN 11105, 168.1 mm SL; MEPN 11102, 218.0 mm SL; MEPN 11114, 2, 153.0– 157.2 mm SL; MEPN 11112, 122.6 mm SL; MUSM 6127, 2, 126.6– 135.4 mm SL; MUSM 6136, 2, 131.5– 135.8 mm SL). Small hooks also present in the anterior main anal-fin branch in the two anteriormost anal-fin rays. Sheath of scales composed of a single series composed by 17–20 rectangular scales, covering basis of anal-fin rays. Pectoral-fin rays i, 12 (28), 13 (24), or 14 (4). Pelvic-fin rays i,7, one specimen i,6, and another single specimen i,8. Branched pelvic-fin rays with minutes hooks (c.10 per branch) on distal portion of posterior ray branches in 14 specimens (MEPN 11101, 205.0 mm SL; MEPN 11108, 155.4 mm SL; MEPN 11115, 144.8 mm SL; MEPN 11109, 2, 149.6– 150.9 mm SL; MEPN 11103, 187.0 mm SL; MEPN 11105, 168.1 mm SL; MEPN 11102, 218.0 mm SL; MEPN 11114, 2, 153.0– 157.2 mm SL; MEPN 11112, 122.6 mm SL; MUSM 6127, 2, 126.6– 135.4 mm SL; MUSM 6136, 2, 131.5– 135.8 mm SL). Main caudal-fin rays 10/9. Caudal fin forked, lobes rounded.
Four branchiostegal rays. First gill arch with 10 (1), 11 (2), or 14 (1) lower gill rakers, 9 (3) or 10 (1) upper gill rakers and 1 at angle. Vertebrae 44 (1).
Coloration in alcohol. Top of head, snout, supraorbital, first, sixth, and fifth infraorbital bones, and dorsal portion of body dark grey to dark brown. Dentary, maxillary, gular area, and ventral portion of body cream-colored. Second through fourth infraorbital bones silvery in specimens retaining guanine, with a brownish tinge. Opercle silvery, with a large, rounded conspicuous dark patch of pigmentation typically lying at its central area, with the exception of darkened large specimens, described below. Humeral blotch present, little conspicuous, more evident in smaller specimens or specimens lacking scales on humeral region, split in two halves. Humeral blotch vertically elongated, lower half more conspicuous, crossed at its middle by the lateral line, extending horizontally from the third to the fourth lateral line scales. Upper half of humeral blotch less conspicuous, separated from lower half of humeral blotch by a narrow clear-colored area, two scales rows high. Lateral portions of body clear, with a silvery hue in specimens retaining guanine. Body with multiple moderately conspicuous longitudinal rows of wavy dark stripes, formed by pigmentation concentrated along scale junctions, more discernible dorsally. Caudal peduncle blotch present, moderately to highly conspicuous, rounded, extending throughout 4–5 last lateral line scales into basis of 5–6 innermost caudal-fin rays. Caudal, anal and dorsal-fins with numerous small dark chromatophores scattered over interradial membranes. Pectoral and pelvic-fins with relatively few dark chromatophores on interradial membranes. Adipose fin light grey, with a well-defined clear area at its basis. Diffuse dark pigmentantion present at lateral portion of body in several middle to large sized specimens (120–220 mm SL, e.g., MEPN 11101, 1, 205.0 mm SL, MEPN 11112, 122.6 mm SL). Some specimens (e.g., MEPN 11115, 3, 164.6–168.0 mm SL; MEPN 11105, 2, 168.1– 173.4 mm SL; MEPN 11103, 187.0 mm SL; MUSM 6141, 145.1 mm SL; MUSM 6136, 3, 131.5– 135.8 mm SL) develop a intense dark pigmentantion on body sides, presenting a much enlarged dark blotch on opercle, covering the entire middle and lower surface of that bone, and sides of body with a marbled pattern, with intense dark and white/silvery pigmentation alternating (see item “Sexual Dimorphism”, below). A single specimen (MEPN 11103, 187.0 mm SL) with a large amount of dark pigmentation on the third to the fifth infraorbital bones.
Color in life. Description based on pictures of several freshly-collected specimens from the Río Machinaza (upper Río Zamora/ Río Santiago basin), taken by R. Barriga and collaborators. Snout, top of head, and dorsum plumbeous-grey to brown; sides of body silvery, with a plumbeous tinge. Lower portion of head and branchiostegal rays clear, tinged with orangish in larger specimens. Dark patch of pigmentation in opercle and caudal-peduncle blotch conspicuous. Longitudinal wavy stripes moderately conspicuous, more discernible dorsally. Pectoral and pelvic-fins reddish. Anal and caudal fin with red pigmentation concentrated at its basis.
Sexual dimorphism. Hooks were observed at the anal-fin rays (and in most cases, also dorsal-fin rays and distal portion of pelvic-fin rays) of 18 specimens (MEPN 11101, 205.0 mm SL; MEPN 11108, 155.4 mm SL; MEPN 11115, 144.8 mm SL; MEPN 11109, 2, 149.6– 150.9 mm SL; MEPN 11103, 187.0 mm SL; MEPN 11105, 168.1 mm SL; MEPN 11102, 218.0 mm SL; MEPN 11114, 2, 153.0– 157.2 mm SL; MEPN 11112, 122.6 mm SL; MUSM 6141, 145.1 mm SL; MUSM 6127, 2, 126.6– 135.4 mm SL; MUSM 6144, 108.2 mm SL; MUSM 6136, 3, 131.5– 135.8 mm SL). Specimen MEPN 11115 (144.8 mm SL) was dissected and is a male, with well-developed testes. On other hand, a specimen lacking any hooks but collected alongside two specimens possessing hooks, MEPN 11114 (182.0 mm SL), proved to be female on dissection, with ripe oocytes. A moderate to intense dark pigmentation on body sides and a enlarged dark blotch on opercle are present in some specimens and seem to be an additional dimorphic feature, since most specimens presenting these color features also present hooks on fins. However, some specimens presenting an enlarged dark blotch on opercle (MEPN 11115, 3, 164.6–168.0 mm SL; MEPN 11117, 2, 147.9– 177.1 mm SL; MUSM 6144, 1, 108.2 mm SL) does not possess any fin hooks, and conversely, some specimens presenting hooks (MEPN 11115, 144.8 mm SL; MUSM 6127, 2, 126.6– 135.4 mm SL) present instead the “normal” color pattern. Brycon guatemalensis is known to possess mature males with a marbled darkened pattern on sides (e.g., Bussing, 1987) and males of Brycon species from all river systems of Pacific versant of the Andes in Ecuador also display a darkened color pattern when mature (R. Barriga, pers. comm..).
Common names. “Blanco”, “sábalo” (Zamora-Chinchipe, Ecuador; R. Barriga, pers. comm.).
Distribution. Brycon coxeyi is only known from upper tributaries of the Río Marañon basin in Ecuador and Peru, at altitudes ranging from 500–1392 meters a.s.l. (Fig. 10).
Ecological notes. Brycon coxeyi is found in fast-running, rocky-bottomed rivers of the Andean piedmont in Ecuador. Two of the the rivers known to harbor Brycon coxeyi populations, the Río Nangaritza and the Río Machinaza, both tributaries of the upper Río Zamora/Río Santiago basin, are fast-running, rocky-bottomed blackwater rivers (R. Barriga, pers. comm..). The Río Comainas in Cordillera del Condor, Peru, where the species also occurs, is a shallow (0.3–1.9 meters deep), relatively small (8–20 meters wide) clear-water river, with a rocky/ gravel/sandy/clay substrate from most of the year, except after heavy rains, when it becomes torrential, with turbid waters (Vari et al., 1995: 294). Crushed vegetal matter (leaves and apparently also fruit remains) were found in two specimens (MEPN 11115, 163.1 mm SL; MEPN 11114, 182.0 mm SL) examined for gut contents. Specimens presenting fin hooks and as such presumably in breeding period were found in March, April, July, September, and November. A female with ripe oocytes (MEPN 11114, 182.0 mm SL) was collected in April and a male with ripe testes (MEPN 11115, 144.8 mm SL) was collected in September. Specimens with a large amount of fat in the abdominal cavitiy were collected in February (MEPN 11119).
Remarks. Fowler (1943: 3) described Brycon coxeyi based on a single specimen collected at the Río Topo in the upper Río Paztaza basin, Ecuador. He noticed that the species was “apparently not closely related to any of the many known forms distributed in the Atlantic drainage of the eastern Andes”, and compared it with to Brycon henni Eigenmann, a species occurring in several trans-andean river drainages of Colombia, and B. stolzmanni. Fowler (1943) incorrectly assumed that the latter could be differentiated from Brycon coxeyi by supposedly lacking the opercular dark patch of pigmentation, when in fact B. stolzmanni possess it. Both species can be differentiated by the characters mentioned in the item “Diagnosis”, above. The holotype (ANSP 70156) is in a very poor condition of preservation, being very soft, with no scales left, most fins broken and the opercle bone almost disarticulated from the rest of the opercular apparatus (see Fig. 11). Still, it displays the rounded dark patch of pigmentation which is characteristic from the remaining Brycon specimens from the upland areas of the Amazon basin in Ecuador herein assigned to the species.
As noticed by Böhlke (1958: 24–25) and Lima (2003: 175–176), the type-locality given by Fowler (1943) for Brycon coxeyi is incorrect, and was amended by the latter as “Ecuador, Napo-Paztaza, Hacienda Mascota, Río Topo, a tributary of Río Paztaza, 1°25’S, 78°11’W”. However, according to the old label present in the jar of the holotype of Brycon coxeyi, the specimen was not collected at the Río Topo itself but rather at the Río Paztaza near the mouth of the Río Topo, and should be again corrected, this time to “Ecuador, Província Tungurahua, Hacienda Mascota, Río Paztaza, near mouth of Río Topo, c. 1°25’S, 78°11’W”.
Boulenger (1898a: 3) examined seven Brycon specimens from the Río Mira and Río Peripa (Río Guayas basin), plus one specimen from the Río Zamora, all of which he identified as Brycon atricaudatus (= B. atrocaudatus). We have not re-examined the specimen from the Río Zamora (which is presumably deposited at the MSNG), but judging both from the locality and its meristic data (lateral line scales 46, scales above lateral line 9, and anal-fin rays 27—i. e., iii, 24— Boulenger, 1898a: 3), this record is with all likelihood referable to Brycon coxeyi. Tortonese (1939: 49) re-examined this same specimen and incorrectly re-identified it as Brycon oligolepis. Géry (1972b: 7–8) cited an unidentified species of Brycon based in specimens collected in the Río Curaray basin (not “Cururay”), a tributary of the Río Napo, Ecuador. Judging by the color pattern and locality data from these specimens, this record might refer to Brycon coxeyi, though anal-fin rays counts are too high (iv, 26–27, according to Géry, 1972: 7). Howes (1982: 21), without presenting any evidence to support such assertion, suggested that Brycon coxeyi might represent a synonym of B. melanopterus. However, both species are very distinct from each other and does not even seem to be closely related (see the account for Brycon melanopterus, below).
Material examined. Type material: ANSP 70156 (1, 131.6 mm SL): Ecuador, Província Tungurahua, Hacienda Mascota, Río Paztaza, near mouth of Río Topo, c. 1°25’S, 78°11’W; W. Judson Coxey, April 1931. Holotype of Brycon coxeyi Fowler.
Non types. Ecuador: Província Zamora-Chinchipe, Río Zamora / Río Santiago basin: MEPN uncataloged (1, 148.5 mm SL): Río Nupatakaine, 500 m from Destacamento Shaine, at confluence with Río Nangaritza, c. 4°28'S, 78°39'W; R. Barriga, 27 July 1993. MEPN 17484 (1, 94.6 mm SL): Quebrada Mayayacu. 2 km from its mouth at Río Nangaritza, 3°59’9’’S, 78°38’27’’W; R. Barriga, 18 July 1993. MEPN uncataloged (1, 192.9 mm SL): Río Nangaritza, near sitio El Dorado, 3°46'S, 78°38'W; R. Barriga & M. Ibarra, 23 Sept 1978. MEPN 17494 (8, 50.4–123.6 mm SL); ZUEC 11325 (1, 106.3 mm SL): Quebrada Yunganza, trib. Río Santiago, 3°24’00’’S, 78°33’25’’W; R. Barriga, M. Ibarra & R. Loma, 27 March 1979. MEPN 11116 (1, 111.2 mm SL): Río Nangaritza; R. Barriga & M. Ibarra, 18 March 1979. MEPN 11114 (5, 153.8–182.0 mm SL): Río Machinaza, 3°45’43’’S, 78°29’53’’W; R. Barriga et al., 14 Apr 2009. MEPN 11115 (6, 152.3– 167.6 mm SL): Río Machinaza, 3°45’43’’S, 78°29’46’’W; R. Barriga et al., 13 Sept 2009. MEPN 11102 (1, 218.0 mm SL): Zamora-Chinchipe, Río Machinaza Grande 0.5 km N of Garita de Aurelean, 3°45’34’’S, 78°29’49’’W; R. Barriga, J. Sandoval & J. Sharupi, 19 Nov 2008. MEPN 11103 (1, 187.0 mm SL): Zamora-Chinchipe, Río Machinaza, Peñas 3°47'1''S, 78°29'35''W; M. Andrade, 23 Jul 2010. MEPN 11104 (2, 149.5– 179.8 mm SL): Zamora-Chinchipe, Río Machinaza, 500 m below confluence with Río La Zanza, 3°45’46’’S, 78°29’46’’W; R. Barriga & M. Andrade, 4 Oct 2009. MEPN 11105 (3, 168.1– 180.9 mm SL): Zamora-Chinchipe, meeting of Río Zarza with Río Blanco, 3°45’44’’S, 78°30’39’’W; R. Barriga, J. Sandoval & S. Charupe, 9 Nov 2008. MEPN 11106 (4, 130.7– 177.1 mm SL): Zamora-Chinchipe, Río Machinaza, 3°45’21’’S, 78°29’34’’W; R. Barriga et al., 13 Sept 2009. MEPN 11106 (4, 130.7– 177.1 mm SL): Zamora-Chinchipe, Río Machinaza, 3°45’21’’S, 78°29’34’’W; R. Barriga et al., 13 Sept 2009. MEPN 11108 (4, 155.4– 177.1 mm SL): Zamora-Chinchipe, Río Machinaza, 0,5 km above confluence with Río La Zalza, 3°45’45’’S, 78°29’46’’W; R. Barriga & M. Andrade, 4 Nov 2009. MEPN 11109 (13, 59.6–150.0 mm SL): Zamora- Chinchipe, Sachavaca Alta, Río Machinaza, 3°41’13’’S, 78°29’27’’W; M. Andrade, 29–30 Jul 2011. MEPN 11110 (4, 79.3–135.8 mm SL): Zamora-Chinchipe, 500 m above confluence of Río Zorza with Río Blanco, 3°45’43’’S, 78°30’38’’W; R. Barriga, J. Sharupe & J. Sandoval, 9 Nov 2008. MEPN 11111 (7, 55.2–124.9 mm SL): Zamora- Chinchipe, Sacha Vaca Alta, Río Machinaza, 3°40’53’’S, 78°29’25’’W; M. Andrade, 3 Aug 2011. MEPN 11113 (6, 147.3– 191.7 mm SL): Zamora-Chinchipe, Río Machinaza, 3°45’46’’S, 78°29’46’’W; R. Barriga et al., 13 Sept 2009. MEPN 11119 (20, 148.3–225.0 mm SL): Zamora-Chinchipe, Rio Machinaza, Peñas; R. Barriga et al., 15 Feb 2010. MEPN 11120 (2, 158.1– 185.9 mm SL): Zamora-Chinchipe, Río Machinaza, Sachavaca, c. 3°42'S, 78°29'W; M. Andrade, 29 Jul–3 Aug 2011. MEPN 11121 (3, 132.8– 158.5 mm SL): Zamora-Chinchipe, Río Blanco, below the bridge, San Antonio, 3°50'49''S, 78°41'41''W; R. Barriga et al., 18 July 2010. MEPN 11117 (4, 39.8–121.2 mm SL): Río Tundayme, trib. Río Santiago, 3°35’29’’S, 78°28’10’’W; no collector specified, 7 Aug 2010. MEPN 11118 (1, 48.0 mm SL): Río Tundayme, trib. Río Santiago, 3°34’35’’S, 78°28’47’’W; no collector specified, 6 Aug 2010. Província Morona-Santiago: MEPN 1979 (4, 119.1– 132.9 mm SL): Morona-Santiago, Río Chuchumbletza, 3°32’20’’S, 78°30’20’’W; R. Barriga, 13 Sept 1978. MEPN uncataloged (1, 50.2 mm SL): Quebrada Chuza, 3 km from Tayuza, c. 2°43’S, 78°15’W; R. Barriga, 7 May 1991. MEPN 11117 (2, 147.9– 177.1 mm SL): Río Chiguaza, trib. Río Paztaza, 2°1'30''S, 77°59'38''W; M. Olalla, 8 Aug 1956. MEPN 5239 (22, 27.8– 47.2 mm SL): Rio Chupianza, 3 km from Chupianza, 2°43’31’’S, 78°18’48’’W; R. Barriga, 6 March 1991. MEPN 5190 (1, 56.0 mm SL): Río Paute at the mouth of río Napiñanza, 2°39’20’’S, 78°23’18’’W; R. Barriga, 7 May 1991. Peru, Depto. Amazonas, Provincia Condorcanqui: MUSM 6136 (10, 52.8–135.8 mm SL); MUSM 6153 (3, 97.3–117.8 mm SL); MUSM 6163 (1, 104.0 mm SL); MUSM 6144 (4, 75.0– 108.2 mm SL); MUSM 6141 (1, 145.1 mm SL); MUSM 6123 (7, 53.4–103.4 mm SL): Río Comainas, tributary of Río Cenepa, at Posto de Vigilancia 22, c. 3°57’40’’S, 78°24’40’’W; H. Ortega et al., 24–28 Jul 1994. MUSM 6127 (8, 82.8–135.4 mm SL); ZUEC 6851 (2, 96.5–105.4 mm SL): Río Comainas, quebrada 3, Posto de Vigilancia 22, 3°57’40’’S, 78°24’40’’W; H. Ortega et al., 21 Jul 1994.
description: Published as part of Lima, Flávio C. T., 2017, A revision of the cis-andean species of the genus Brycon Müller & Troschel (Characiformes: Characidae), pp. 1-189 in Zootaxa 4222 (1) on pages 21-26, DOI: 10.5281/zenodo.257769