Brycon stolzmanni Steindachner, 1879
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|Brycon stolzmanni Steindachner, 1879|
Brycon stolzmanni Steindachner, 1879a: 152 (Type locality, “Chota”; brief description); Steindachner, 1879b: 170, pl. 2, figs.6, 6a (full description); Pearson, 1937: 90 (Peru: Balsas; Paipay, Rio Crisnejas; Tingo de Pauca, Rio Marañon; Pusoc, above Balsas).
Diagnosis. Brycon stolzmanni can be distinguished from all remaining cis-andean Brycon species, except B. coxeyi , 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 stolzmanni can be distinguished from B. coxeyi by possessing the dark patch of pigmentation on the opercle diffuse and covering the upper half of the bone (vs. dark patch of pigmentation on opercle very conspicuous and typically lying at its center).
Description. Morphometric data are presented in Table 1 View TABLE 1 . Relatively small-sized species, largest examined specimen 214.0 mm SL. Body moderately high. Largest body height at dorsal-fin level. Dorsal body profile slightly convex from upper lip margin to vertical through anterior naris, slightly concave to slightly convex 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, slightly convex to straight from this point to anal-fin origin and approximately straight along anal-fin base. Ventral profile of caudal peduncle slightly concave.
Head profile rounded to slightly acute anteriorly, mouth terminal. 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 (7), 6 (16), 7 (10) or 8 (1) tricuspidate teeth in outer series. Two (4), 3 (25), or 4 (7) tri- to pentacuspidate teeth in second, inner premaxillary row, plus 3 (30) or 4 (6) 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. Eleven to 18 maxillary teeth, slightly smaller than teeth of first premaxillary row, anterior teeth tricuspidate, posterior teeth unicuspidate. Dentary with 6 (1), 7 (3), 8 (1), 9 (1), or 10 (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 5 small, unicuspidate teeth, originating at level of 7th tooth of main series.
Scales cycloid. Lateral line complete, from supracleithrum to caudal-fin base. Forty-three (1), 44 (3), 45 (6), 46 (10), 47 (12), 48 (3), or 49 (1) scales in lateral line series; laterosensory tube simple, tube often deflected downwards. Horizontal scale rows between dorsal-fin origin and lateral line 8 (17), 9 (16), or 10 (3). Horizontal scale rows between lateral line and pelvic-fin 4 (4), 5 (15), or 6(17). Circumpeduncular scales 16 (18), 17 (9), or 18 (9).
Dorsal-fin rays ii, 9. Dorsal fin origin slightly anterior to middle of SL. First dorsal-fin pterygiophore inserting behind neural spine of 12th vertebrae. Dorsal fin displaying numerous (c. 10–35 per fin-ray main branch) small hooks on last unbranched and posterior main branch of all branched rays in one specimen ( ROM 55348 View Materials , 128.8 mm SL). Anal-fin rays iii (not including first, small unbranched ray only visible in the cs specimen), 19 (1), 20 (6), 21 (16), 22 (12), or 23 (1). First anal-fin pterygiophore inserting behind haemal spine of 22th vertebrae. Last unbranched and anterior 2–3 branched anal-fin rays longer, remaining rays progressively shorter towards anal-fin end. Anal fin displaying numerous (c. 15–35 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 one specimen ( ROM 55348 View Materials , 128.8 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 16–20 rectangular scales, covering basis of anal-fin rays. Pectoral-fin rays i, 11 (1), 12 (15), 13 (18), or 14 (2). Pelvic-fin rays i,7. Branched pelvic-fin rays with minutes hooks (c.10 per branch) on distal portion of posterior ray branches in one specimen ( ROM 55348 View Materials , 128.8 mm SL). Main caudal-fin rays 10/9. Caudal fin forked, lobes rounded.
Four branchiostegal rays. First gill arch with 11(1) lower gill rakers, 11(1) upper gill rakers and 1 at angle. Vertebrae 43 (1). Supraneurals 9 (1).
Coloration in alcohol. Top of head, snout, supraorbital, sixth and dorsal portion of fifth infraorbitals, and dorsal portion of body dark grey to dark brown. Dentary, maxillary, lower infraorbitals, gular area and ventral portion of body light to cream-colored. Opercle dark-colored, its lower half dark-grey, suffused with silvery pigmentation, while upper half dark brown. Humeral blotch present, split in two halves, lower half more conspicuous, roughly triangular-shaped, with the apex directed downwards, crossed at its lower portion by the lateral line, extending horizontally from the third to the fifth to sixth lateral line scales. Upper half of humeral blotch less conspicuous, separated from lower half of humeral blotch by a narrow clear-colored area, two and a half scales rows high. Caudal peduncle blotch present, relatively conspicuous, rounded, extending throughout 3–4 last lateral line scales into basis of 3–4 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 dark brown, with a conspicuous clear-colored rounded spot at its basis.
Sexual dimorphism. The single examined specimen bearing hooks on dorsal, pelvic- and anal-fins ( ROM 55348 View Materials , 128.8 mm SL) was found to be a male upon dissection. The largest specimen examined, NMW 62728 View Materials (214.0 mm SL), is a female with well-developed ovaries, which does not possess fin hooks.
Distribution. Brycon stolzmanni is known from the upper Río Marañon and its tributaries at the Departamentos Cajamarca, Lambayeque, and Amazonas, Peru ( Fig. 10 View FIGURE 10 ). Fowler (1943: 4) and Howes (1982: 44) incorrectly assigned the species for the Pacific slope of the Andean cordillera.
Ecological notes. Brycon stolzmanni is recorded from Andean rivers in altitudes ranging at least from 870– 1087 meters high. The type locality, Chota, is situated in the headwaters of the Río Chamaya, a tributary of the upper Río Marañon, at a considerably higher altitude (2400 meters high). However, its is uncertain whether the type specimens were collected at Chota itself or in a neighboring river valley, and consequently we did not included this record in the altitudinal range cited above. The Río Marañon and its tributaries at the area of occurrence of Brycon stolzmanni are swift-flowing, white-water rivers possessing coarse gravel and rocky substrates running over braided channels, deeply entrenched in valleys crossing the mountains.
Remarks. Steindachner (1879a: 152) succinctly described Brycon stolzmanni , a complete description and a illustration of the species appearing a little later (1879b: 22). The species was described based on two specimens collected at Chota, upper Río Marañon basin, Departamento Cajamarca, Peru. The two syntypes (NMW 62731) were examined, the largest of which is herein designated as the lectotype of the species. There have been almost no subsequent published information on the species, and in fact, Pearson (1937) report of the species for several localities in the upper Río Marañon basin in Peru was the sole paper to add original information on the species up to now.
Material examined. Type material. NMW 62731 View Materials :1 (1, 124.5 mm SL): Chota ( Peru, Depto. Cajamarca, Rio Marañon basin, c. 6°33’S, 78°39’W); Stolzmann, no date GoogleMaps . Lectotype by present designation of Brycon stolzmanni Steindachner. NMW 62731 View Materials :2 (1, 88.4 mm SL); same data as lectotype GoogleMaps . Paralectotype.
Non types. All from Peru, Rio Maranõn drainage. Departamento Cajamarca: ROM 52237 View Materials (5 of 51, 146.8– 160.5 mm SL), approx. 74 km W of road going N to Jaen , between Pucara and Guabal, Chamaya River, Huacabamba River (tributary Amazon / Marañon drainage), c. 5°57’S, 79°13’W; E. Holm & J. Patalas, 8 Jul 1986 GoogleMaps . CAS 77371 View Materials (69, 27.3–72.5 mm SL), Rio Crisnejas, at mouth of Rio Paipay at Paipay , c. 7°21’S, 77°53’W GoogleMaps ; N.E. Pearson, Aug 1923. NMW 62728 (1, 214.0 mm SL); NMW 62933 View Materials (1, 88.5 mm SL), Celendín, Hacienda Callacate , 6°46'S, 78°16'W GoogleMaps ; W. Taczanowski, 1880. MUSM 41333 (9, 20.5–37.2 mm SL): Celendín , Río Llanguat (Río Marañon basin), 6°47’19’’S, 78°12’55’’W; H. Ortega et al., 25 Sept 2011 GoogleMaps . Departamento Amazonas: ROM 55347 View Materials (1, 163.7 mm SL), Luya, Huanabamba, about 16 km by road upstream from Balsas , Amazon / Marañon drainage, 6°52'S, 78°00'W; E. Holm et al., 27 June 1986 GoogleMaps . ROM 55348 View Materials (2, 128.8– 132.7 mm SL), confluence of “El Río ” (creek running through Balsas) at Puerto Balsas , 6°50'S, 78°01'W GoogleMaps ; E. Holm et al., 28 Jun 1986. UMMZ 185306 (28, 49.6–130.7 mm SL); UMMZ 216716 View Materials (5, 107.3– 185.5 mm SL): Rio Maranõn at Balsas , 6°50’S, 78°1’W; N.E. Pearson, July 1923 GoogleMaps . CAS 77370 View Materials (ex IU 17599) (6 of 94, 20.9–33.2 mm SL), Río Marañon, Pusoc (Guayabamba), above Balsas , c. 6°57’S, 78°00’W GoogleMaps ; N.E. Pearson, Aug 1923. CAS 77372 View Materials (32, 21.5–42.9 mm SL), Río Marañon at Tingo de Pauca , mouth of Río Crisnejas, c. 7°20’S, 77°49’W GoogleMaps ; N.E. Pearson, Sept 1923. MUSM 10611 (5, 65.8–94.0 mm SL): Río Uctubamba, Lluhuana; F. Chang, 23 Nov 1996 . MUSM 40548 (1, 85.0 mm SL): Bongará, Shipasbamba , Río Uctubamba (trib. Río Marañon), 5°54’45’’S, 78°3’50’’W GoogleMaps ; M. Jaico et al., 12 Jul 2011. MUSM 41145 (44, 45.9–105.2 mm SL); ZUEC 6850 View Materials (4, 58.9–101.4 mm SL): Amazonas, Bongara, Jazan , Río Tingo (trib. Río Uctubamba), 5°55’2’’S, 78°4’35’’W GoogleMaps ; M. Hidalgo & I. Corahua, 29 June 2011 . MUSM 41146 (8, 62.1–99.0 mm SL): Amazonas, Bongara, Jazan , Río Utcubamba (island), 5°55’1’’S, 78°4’32’’W GoogleMaps ; M. Hidalgo & I. Corahua, 29 June 2011 . Departamento Lambayeque: MUSM 30230 (1, 35.5 mm SL): Ferreñafe, Kañaris , CCA Huancabamba , Río Cañariaco, mouth at Río Huancabamba, 5°56’15’’S, 79°15’47’’W GoogleMaps ; B. Renjifo & V. Meza, 24 May 2007. Without data: MUSM uncat. (1, 133.7 mm SL, cs).
|Standard length (SL)||124.5||36||66.6–185.5||-|
|Percentages of standard length|
|Depth at dorsal-fin origin||33.0||36||29.9–34.0||31.8|
|Snout to dorsal-fin origin||52.0||36||48.5–53.4||51.0|
|Dorsal-fin base length||12.4||36||10.6–14.9||12.6|
|Posterior terminus of dorsal fin to adipose fin||21.8||36||21.1–26.6||23.6|
|Posterior terminus of dorsal fin to hypural joint||39.0||36||35.5–42.9||39.0|
|Snout to pelvic-fin insertion||52.0||34||47.9–53.3||49.9|
|Snout to anal-fin origin||69.4||36||63.3–69.4||66.0|
|Anal-fin base length||22.5||35||19.4–23.9||22.0|
|Caudal peduncle length||13.5||36||13.5–18.8||17.1|
|Caudal peduncle depth||11.5||36||10.2–12.1||11.4|
|Percentages of head length|
|Upper jaw length||42.9||35||40.4–45.3||43.2|
|Horizontal eye diameter||21.3||36||21.3–28.9||24.0|
|Least interorbital width||32.0||35||27.0–37.5||32.1|
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