Brycon whitei Myers & Weitzman, 1960

Lima, Flávio C. T., 2017, A revision of the cis-andean species of the genus Brycon Müller & Troschel (Characiformes: Characidae), Zootaxa 4222 (1), pp. 1-189 : 108-112

Brycon whitei Myers & Weitzman, 1960

( Figs. 63–64 )

Brycon whitei Myers & Weitzman, 1960: 99 –103, fig. 1 (Type locality: “vicinity of Los Micos, and the north end of Cordillera Macarena, at aproximately 3°20´N., 73°56´W. This locality is the headwaters of the Río Guaviare (Río Orinoco system) just east of Cordillera Oriental in Colombia”); Mago-Leccia, 1970: 69, 281 (listed; Venezuela; common name, photo); Cala, 1977: 7 (Rio Orinoco basin, Colombia); Lilyestrom & Taphorn, 1983: 53 –59 (La Canoa, upper Río Tucupido, Río Apure drainage, Venezuela; length/weigth relationships, mean size, condition factor, diet, conservation); Winemiller, 1989a: 231, 234, 236, 238–239 (Venezuela, Portuguesa, Río Apure drainage; reproduction); Taphorn, 1992: 131 –133, 490, 494, 500, 508, 512, fig. (Rio Apure drainage, Venezuela; description, ecology, biology, distribution in the Río Apure drainage); Lasso et al., 1999: 24 (Rio Apure, Estado Apure, Venezuela); Hoeinghaus et al., 2004: 91 (occurrence, río Portuguesa drainage); Lasso, 2004: 99–100, figure 66 (Venezuela, Apure, Estación Biológica El Frío and Caño Guaritico; natural history, variation); Taphorn et al., 2005: 25 (P.N. Aguaro-Guariquito, Venezuela); Maldonado-Ocampo et al., 2006: 120 (Río Tomo, departamentos Meta and Vichada, Colombia); Rodríguez-Olarte & Taphorn, 2006: 75 –78 (Rio Apure drainage, Estado Portuguesa, Venezuela: sociality and predation by Salminus sp.). [not Saul, 1975: 103].

[Doubtful record: Rodríguez & Lewis, 1997: 112 (floodplain lakes, Río Orinoco, Venezuela)].

Diagnosis. Brycon whitei can be unambiguously diagnosed from all cis-andean congeners by the possession of an autapomorphic broad, dark, midlateral stripe extending from supracleithrum area to caudal peduncle and into median caudal-fin rays. Among congeners, Brycon whitei is more similar to B. hilarii . Brycon whitei specimens with poorly developed longitudinal stripes are very similar to B. hilarii specimens with well-developed caudal peduncle stripes, which in those specimens extend forward to the level of dorsal fin. However, Brycon whitei can be additionaly diagnosed from the latter species by possessing tiny stripes on caudal-fin rays (vs. tiny stripes on caudal-fin rays absent in B. hilarii ).

Description. Morphometric data are presented in Table 17 . Large-sized species, largest examined specimen 343.5 mm SL. Body moderately slender to 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, straight to slightly concave from latter point to basis of supraoccipital process, moderately convex from latter point to dorsal-fin origin, straight along dorsal-fin basis, and straight to slightly convex from dorsal-fin basis 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 to slightly anisognathous, outer row of premaxillary teeth partially exposed when mouth is closed. Maxillary moderately long, extending posteriorly to middle of pupil. Adipose eyelid well developed. Premaxillary teeth in three rows; teeth of third row largest. Eight (4), 9(5), 10 (5), 11(4), 12(2), or 13(1) relatively small tricuspidate teeth in outer series. Three (3), 4 (8), or 5 (10) tri- to pentacuspidate teeth in second, inner premaxillary row, plus 3 (2), 4 (18), or 5 (1) tricuspidate teeth between the first and third rows. Two teeth in third premaxillary row, medial teeth largest, symphyseal teeth smaller, slightly tilted towards each other, both hexacuspidate. Maxillary margins approximately parallel, straight in profile. Twelve to 23 maxillary teeth, slightly smaller than teeth of first premaxillary row, anterior teeth tricuspidate, posterior teeth unicuspidate. Dentary with 8 (2), 9 (2), or 11 (2) 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 small, single unicuspid symphyseal tooth, situated immediately posterior to symphyseal dentary teeth of main series, plus row of 14 small, aciculated, unicuspidate teeth, originating on lingual crest of dentary replacement trench at the level of fifth to sixth main series dentary teeth.

Scales cycloid. Lateral line complete, from supracleithrum to caudal-fin base. Sixty-six (4), 67(3), 68(3), 70(7), 71(1), 73(1), 74(1), or 76(1) scales in lateral line series. Laterosensory tube ramified tubules ramification increasing in complexity along ontogeny, specimens up to 150 mm SL with tubules with two to four branches, three to five branches in specimens around 200 mm SL, and with more than 6 branches and developing a dendritic pattern of ramification, with tubules often overlapping each other in specimens around 250 mm SL. Horizontal scale rows between dorsal-fin origin and lateral line 12(7) or 13(14). Horizontal scale rows between lateral line and pelvic-fin 7(7), 8(9), or 9(5). Circumpeduncular scales 19 (1), 21 (9), 22(7), 23(3), or 24(1).

Dorsal-fin rays ii, 9. Dorsal fin origin slightly after to slightly ahead middle of SL. First dorsal-fin pterygiophore inserting behind neural spine of 14th (1) vertebra. Anal-fin rays iii (not including first, small unbranched ray only visible in cs specimens), 21 (7), 22(7), 23(3), or 24(4). First anal-fin pterygiophore inserting behind haemal spine of 31th (1) vertebra. Anal-fin rays decreasing only slightly in size towards anal-fin end. Sheath of scales covering basis of anal-fin rays composed of four scale rows, lower scale row formed by 20–21 rectangular scales. Pectoral-fin rays i, 12 (2), 13 (10), or 14 (9). Pelvic-fin rays typically i, 7, one specimen i, 6, and two specimens i, 8. Main caudal-fin rays 10/9. Caudal fin slightly forked, distal margin slightly concave. Central caudal-fin rays presenting in some specimens with a small, pointed middle projection extending beyond primary margin of fin. Laterosensory tube extending over interradial membrane between upper and lower caudal-fin lobes to the distal portion of fin. Laterosensory tube on caudal fin with dorsally and ventrally oriented side branches across its length.

Four branchiostegal rays, three on anterior ceratohyal and one on posterior ceratohyal. First branchial arch with 15 (1) or 17 (1) lower, 1 at angle, and 13 (1) or 16 (1) upper gill rakers. Vertebrae 47 (1). Supraneurals 11 (1).

Coloration in alcohol. Top of head, snout, supraorbital, sixth and sometimes fifth infraorbitals, and upper half of opercle light-gray to dark-brown. Dorsal portion of body light-gray to dark-brown. Second, third, fourth, and fifth infraorbitals, and opercle silvery in specimens that retained guanine, light- to dark-brown in specimens that lost this pigment due to a long storage in formalin. Dentary, maxillary, gular area, and lower portion of body lightbrown. Lateral portion of body light brown, with a silvery hue in specimens retaining guanine. Humeral blotch present, conspicuous, approximately rounded in shape, situated immediately above lateral line, its anterior margin at level of second, extending longitudinally to posterior margin of fifth to sixth lateral line scales, and vertically one and half scales high. Dark, wavy longitudinal stripes formed by dark pigment concentrated on upper and lower scale margins extending along trunk. Stripes more discernible dorsally. Broad, conspicuous longitudinal dark stripe extending at the level of lateral line from supracleithrum to caudal-peduncle and into middle caudal-fin rays to caudal-fin margin. Dark stripe two to two and half scales high. Some relatively small specimens (INHS 60221, CAS (SU) 53787, CAS 64340) with a relatively faint, poorly developed stripe, only developed after at the level of dorsal-fin terminus. Caudal-fin rays with moderately conspicuous, short, elongate, tiny vertical stripes on fin rays. Remaining fins clear, pectoral fins darkened in larger specimens.

Coloration in life. Description based on pictures published by Géry (1977: 325, upper picture, as Brycon sp.), Lilyestrom & Taphorn (1983: 55), and pictures from specimens collected at the Río Negro (tributary of Río Casanare), Colombia, by A. Linares. Overall ground color clear, with a silvery hue, top of head, snout and dorsum gray. Longitudinal dark stripe conspicuous, more evident at the level of dorsal fin posteriorly towards caudal peduncle. Pectoral fin dark gray. Dorsal and adipose fins gray. Pelvic, anal, and caudal-fins pinkish.

Sexual dimorphism. Anal fin displaying numerous (c. 15 per fin-ray main branch) small hooks on last unbranched and posterior main branch of branched rays 1–8 to 10, associated with dense, gelatinous tissue in two specimen (MZUSP 105834, 250.0–254.0 mm SL). A single hook per ray segment, a few hooks at the anterior branch of some anal-fin rays. One of these specimens was dissected and proved to be a male.

Common names. Venezuela: “Palambra” ( Lilyestrom & Taphorn, 1983; Taphorn, 1992). Colombia: “bocón” ( Cala, 1977: 7); “sardinata”.

Distribution. Endemic from the Río Orinoco basin in Venezuela and Colombia, where it is widespread, with a clear preference for piedmont areas ( Taphorn, 1992) ( Fig. 65 ).

Ecological notes. Inhabits mountain, piedmont and high llaneran streams and rivers, preferring clear waters, with strong currents ( Taphorn, 1992; Rodríguez-Olarte & Taphorn, 2006). It generally prefers river with an intact gallery forest ( Taphorn, 1992). Brycon whitei is most often found in schools ( Taphorn, 1992), sometimes mixed with small specimens of Salminus sp. ( Rodríguez-Olarte & Taphorn, 2006). The diet of the species was studied by Lilyestrom & Taphorn (1983), who examined stomach contents of 68 specimens and found it constituted mainly (82 %) by vegetal matter (seeds, fruits, leaves), with a smaller amount of animal matter (11 %), constituted by terrestrial insects, small fishes and a lizard. Lasso (2005: 100) examined two stomach contents and found crushed seeds and unidentified vegetal matter. The species is highly fecund (more than 170.000 eggs), breeding during the first month of the wet season ( Winemiller, 1989a; Taphorn, 1992). Brycon whitei undertakes upstream migrations (“ribazones”) in the early dry season (October/December) and downstream migrations during the onset of the rainy season (May to June) ( Taphorn, 1992). Brycon whitei is highly ranked for both recreational and subsistence fisheries ( Lilyestrom & Taphorn, 1983; Taphorn, 1992). The species is reported to reach 450 mm SL and 4 kg ( Taphorn, 1992), being consequently one of the largest species in the genus.

Conservation. Loss of habitat due to deforestation, damming, pollution and water diversion for irrigation projects has caused considerable declines and even local extinctions of populations of Brycon whitei in the piedmont and high llanos area of Venezuela ( Lilyestrom & Taphorn, 1983; Taphorn, 1992).

Remarks. Brycon whitei is a distinctive species that has been generally correctly identified since its original description. The only obvious misidentification present in the literature is the record by Saul (1975) of Brycon cf. whitei from the Río Conejo, a tributary of Río Aguarico, Napo, Ecuador. Although the specimens basing that record were not examined during the present study, this record almost certainly refers to Brycon hilarii , a similarlooking species known from the Río Napo basin (see under this species).

Material examined. Type material. CAS (SU) 48818 (1, 343.5 mm SL): Colombia, Estado Meta, Río Guaviare [= actually Río Güejar according to maps], vicinity of Los Micos , c. 3°20’N, 73°56’W; T.D. White, J.N. Reynolds & L. Wulff, Feb 1956 . Holotype of Brycon whitei Myers & Weitzman. CAS (SU) 48817 (1, 238.0 mm SL): same data as holotype . Paratype of Brycon whitei Myers & Weitzman.

Non types. Colombia: CAS (SU) 53787 (1, 151.5 mm SL): Estado Meta , Río Guayabero , Cordillera Macarena, small brook 3 mi. below El Refugio , 2°16'N, 73°46'W ; T.D. White & G.S. Myers, 24 Feb 1960. Venezuela, estado Cojedes: INHS 60211 (1, 192.5 mm SL) : Río Pao ( Río Portugueza - Río Apure dr.), W La Yeguera, at Hwy. Bridge, 9°32’25’’N 68°6’54’’W ; L.M. Page et al., 22 Dec 1990. Estado Guárico: MZUSP 106459 (ex MCNG 24231 ) (2, 143.7– 157.2 mm SL): caño 8.5 km S of Palenque, río El Burro , 8°47’N, 66°52’W ; L.G. Nico et al., 11 Sept 1989. FMNH 85445 (2, 120.7– 123.2 mm SL): Rio Manapire drainage, 113.1 km south of Chaguaramas , 2.5 km east of highway, tributary of Rio Manapire, 8°20’N, 65°7’W ; J.E. Thomerson, D. Hicks, D. Taphorn, T. & D. Greenfield, 5 Jan 1975. Estado Portuguesa: MZUSP 106460 (ex MCNG 90 ) (2, 151.8– 177.8 mm SL) : Río Las Marias, 800 m above bridge, 4 Km from Guanare, 9°5’40’’N, 69°30’20’’W; D.C. Taphorn et al., 26 Feb 1979. CAS 64340 (2, 174.7– 178.6 mm SL) : Río Maria at bridge on Guanare-Acarigua highway, c. 9°5’N, 69°30’W; D. Taphorn et al., 16 Feb 1981. MZUSP 105834 (2, 250.0–254.0 mm SL) : Río Tucupido, trib . Río Guanare, 15 km SW Guanare , 8°54’51’’N, 69°45’40’’W ; N.K. Lujan et al., 17 March 2010. Estado Barinas: INHS 61310 (1, 191.0 mm SL) : Río Canaguá (Río Apure drainage), 10 km NNW Ciudad Bolivia, Rt. 5 bridge, 8°25’37’’N, 70°38’21’’W; L.M. Page et al., 10 Jan 1992. USNM 219726 (4, 264.9– 306.8 mm SL) : Rio Las Palmas (trib. Río Paguey), c. 8°4’N, 70°20’W ; P. Bottome & Wallis, 15 Jul 1958.

Figures

FIGURE 63. Brycon whitei, holotype, CAS (SU) 48818, 343.5 mm SL: Colombia, Meta, Río Guaviare.

FIGURE 64. Brycon whitei, INHS 61310, 191.0 mm SL: Venezuelas, Barinas, Río Canaguá.

FIGURE 65. Map of northern South America, showing localities of examined material of Brycon whitei (red dots).

Tables

TABLE 17. Morphometric data of Brycon whitei (A: holotype, CAS (SU) 48818).

	A	n	Range	Mean
Standard length (SL)	343.5	21	120.7–343.5	-
Percentages of standard length
Depth at dorsal-fin origin	31.8	21	27.5–35.2	31.1
Snout to dorsal-fin origin	50.8	21	48.0–53.0	50.2
Dorsal-fin base length	10.4	21	10.4–13.2	12.1
Posterior terminus of dorsal fin to adipose fin	26.7	21	21.8–26.7	23.8
Posterior terminus of dorsal fin to hypural joint	41.9	21	32.5–42.7	38.9
Snout to pelvic-fin insertion	46.6	21	44.1–49.9	47.3
Snout to anal-fin origin	69.1	21	64.5–71.1	67.6
Anal-fin base length	18.8	21	18.8–23.5	22.0
Caudal peduncle length	13.9	21	13.3–17.2	15.0
Dorsal-fin height	19.0	20	17.8–22.4	20.6
Pectoral-fin length	59.9	21	56.0–71.7	64.3
Pelvic-fin length	16.2	20	14.7–19.1	17.1
Caudal peduncle depth	8.6	21	7.5–10.1	9.3
Head length	24.0	21	22.8–29.2	26.0
Percentages of head length
Head height	83.4	21	73.7–84.8	79.5
Snout length	34.0	19	26.6–34.2	32.0
Upper jaw length	60.3	21	45.4–60.3	49.4
Horizontal eye diameter	17.7	21	17.6–28.9	23.9
Post-orbital length	52.9	21	41.7–53.2	48.4
Least interorbital width	46.8	21	39.7–48.8	44.7