Overview

Comprehensive Description

[[ Genus Bryconops ]]

The genus Bryconops contains 15 species (Chernoff et al., 1994, 2002; Chernoff and Machado-Allison, 1999; Machado-Allison et al. 1993, 1996; Machado-Allison and Chernoff, 1997), including the two species that are described herein. The genus is widely distributed in the cis-Andean lowlands of South America from the Orinoco to the Paraná- Paraguay basins including many coastal basins of the Guyanas and Brazil. Although B. alburnoides Kner, 1859 , is known to inhabit relatively basic, white-water habitats (e.g., flood plain lakes of the lower Orinoco [ Rodríguez and Lewis, 1990]), most species are found in lotic habitats that are typically acidic and transparent, despite the color of the water. Many species inhabit morichal (aguajal, vereda) habitats that are dominated by the moriche palm ( Mauritia sp.).

The two new species inhabit the Orinoco and Cuyuni watersheds (Fig. 1). The latter occurs on the Guyana Shield above the cataracts in the Essequibo River basin. The two new species belong to the subgenus Bryconops because of the synapomorphies of the jaws and gill rakers that they share (discussed below) with the other members of the subgenus: Bryconops alburnoides , Bryconops caudomaculatus ( Guenther , 1864) , Bryconops disruptus Machado-Allison and Chernoff, 1997 , and Bryconops durbini (Eigenmann 1908) . Within this group the new species superficially resemble B. caudomaculatus , an enigmatic taxon, B. disruptus , and B. durbini because of the colorful ocellus on the dorsal lobe of the caudal fin. Indeed, the new species have been identified as B. caudomaculatus in collections.

In this paper we describe two new species of the genus Bryconops , compare them with other member of the subgenus, and discuss some aspects on the morphometry and shape changes in these species. We comment on the characteristics of B. caudomaculatus in order to clarify its status. Lastly, we provide an artificial key to the species of Bryconops .

  • Barry Chernoff, Antonio Machado-Allison (2005): Bryconops magoi and Bryconops collettei (Characiformes: Characidae), two new freshwater fish species from Venezuela, with comments on B. caudomaculatus (Gunther). Zootaxa 1094, 1-23: 2-3, URL:http://www.zoobank.org/urn:lsid:zoobank.org:pub:2847B8DC-ED42-4562-9EF6-A4E8DC5F59A0
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Comparisons within the subgenus Bryconops

Bryconops collettei ZBK and B. magoi ZBK possess the derived characters of the subgenus Bryconops (Chernoff and Machado-Allison, 1999), which include reduction in the ossification and denticulation of the gill rakers, despite being large fishes, and lack of maxillary teeth, with at most (and rarely) only a single, small conical tooth on one side. The subgenus Bryconops contains six species. B. alburnoides differs from the other five species by being much larger, reaching almost 200mm SL, and by having more lateral scales and branched anal-fin rays (see key). Importantly, B. alburnoides lacks an ocellus or clear areas containing coloration on the caudal fin. B. alburnoides often has pale to bright yellow suffused among the caudal fin rays, but this color is not concentrated within a circumscribed area on either fin lobe. Furthermore, the dorsal and adipose fins of B. alburnoides are dusky to pale yellow, never red.

The remaining five species in this subgenus comprise the B. caudomaculatus species complex. We refer the five species to this informal group because of their phenotypic similarity and because they have all been referred to, or synonymized with B. caudomaculatus at some point in their history. The following characteristics are common to the complex: (i) the dorsal fin has a crescent of red (a potential synapomorphy), (ii) the adipose fin is entirely red, and (iii) the caudal fin has at least a clear circumscribed area on the upper lobe that is either entirely, or partially, filled with red color. This ocellus is either well formed or irregular (Fig. 2). B. magoi ZBK and B. collettei ZBK differ from the other members by having the dorsal-fin ocellus only partially filled with red color (Fig. 3), the overall form of which appears as a streak or narrow ellipse; the color becomes diffuse and extends beyond the ocellus among the upper caudal-fin rays. This condition in the new species is independent of sex or state of maturity, since even specimens as small as 35 mm SL show the diffuse coloration pattern, though the color may be slightly less intense. Both B. disruptus and B. durbini have very few pored lateral scales (<31), whereas B. caudomaculatus , B. collettei ZBK , and B. magoi ZBK have more numerous pored scales (>36) that extend nearly to or beyond the end of the hypural plate.

  • Barry Chernoff, Antonio Machado-Allison (2005): Bryconops magoi and Bryconops collettei (Characiformes: Characidae), two new freshwater fish species from Venezuela, with comments on B. caudomaculatus (Gunther). Zootaxa 1094, 1-23: 5-6, URL:http://www.zoobank.org/urn:lsid:zoobank.org:pub:2847B8DC-ED42-4562-9EF6-A4E8DC5F59A0
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Artificial key to the species of Bryconops

1 Posterior extension of maxilla not reaching junction of second and third infraorbital bones. Border between second and third infraorbital bones leaving a small naked triangle between them. Maxilla without teeth, rarely a single small conical tooth, usually on just one side (subgenus Bryconops )........................................................................ 2

- Posterior extension of maxilla reaching junction of second and third infraorbital bones. Ventro-posterior margin of second infraorbital squared-off, forming a complete border with third infraorbital, without naked area between them. Maxilla with one to three teeth on both sides (subgenus Creatochanes ) ..............................................................7

2 Snout pointed slightly. Lower jaw included in upper jaw when closed. Premaxillary teeth generally in three rows. Caudal fin with yellow in life on both dorsal and ventral portions, lacking any ocellus; posterior margin dusky to dark. Anal fin long with 32- 37 branched rays. Pored lateral line scales 57-61. Scales above lateral line 9-10. Scales below lateral line 5-6.................................................................... B. alburnoides

- Snout blunt and rounded. Lower jaw terminal or only slightly included in upper jaw. Premaxillary teeth generally in two rows. Caudal fin with well formed ocellus on dorsal lobe, intense red in life (clear in preserved material); remainder of fin dark to dusky. Anal fin with 22-30 branched rays. Pored lateral line scales 9-43. Scales above lateral line 7-8. Scales below lateral line 4-5................................................... 3

3 Pored lateral line scales>36, extending beyond base of last anal fin ray.................... 4

- Pored lateral line scales <31, not extending to base of last anal fin ray.......................6

4 Pored lateral scales reaching end of hypural plate. Ocellus on dorsal lobe of caudal fin well-formed, completely filled with red color. Clear area at base of ventral lobe of caudal fin with red color.................................................................. B. caudomaculatus

- Pored lateral scales extending 2-3, rarely 1, scales beyond hypural plate onto caudal fin rays. Ocellus on dorsal lobe of caudal fin irregular or diffuse, only upper half filled with red color. Without red color in ventral lobe of caudal fin................................... 5

5 Snout length 5.8-8.0% SL (mean 6.8%). Length of anal fin base 24.8-27.9% SL (mean 26.6%). Lateral scales 41-44, modally 42. Pored lateral scales 43-47, modally 44-45. Total vertebrae 40-42, modally 41-42. Gill rakers on lower arch, 8-10, modally9 ....................................................................................................... B. magoi ZBK , n. sp.

- Snout length 4.2-5.4% SL (mean 4.7%). Length of anal fin base 27.3-29.8% SL (mean 28.8%). Lateral scales 42 - 45, modally 44. Pored lateral scales 44- 48, modally47. Total vertebrae 42-44, modally 43. Gill rakers on lower arch, 8-11, modally 11 ............................................................................................................. B. collettei ZBK , n. sp.

6 Pored lateral line scales not extending beyond second or third branched anal fin rays, 9-23 pored scales. Branched anal fin rays 26-28 ..................................... B. disruptus

- Pored lateral line scales extending beyond third branched anal fin ray, 30 pored scales. Branched anal fin rays 25 ............................................................................... B. durbini

7 Humeral mark(s) present .............................................................................................. 8

- Humeral mark(s) absent ............................................................................................. 10

8 Two humeral marks. Dark to dusky pigment obscuring the caudal peduncle from over the middle of the anal-fin base onto the central part of the caudal fin. Caudal fin dusky without ocelli on either lobe. Body metallic blue in life ................................. B. inpai

- Single humeral mark. Caudal peduncle not obscured by pigment. Caudal fin with ocellus on dorsal lobe. Body silver to olivaceous in life ............................................ 9

9 Scales below lateral line 4-5. Gill rakers on the lower limb of first arch 10-11. Caudal peduncle least depth 6.6-10.2 % SL (mean 8.0 % SL). Upper jaw length 11.8-16.9 % SL (mean 14.5 % SL) ................................................................................. B. humeralis

- Scales below lateral line 6. Gill rakers on lower limb of first arch 9-10. Caudal peduncle least depth 9.2-11.1 % SL (mean 10.0 % SL). Upper jaw length 15.2-20.6 % SL (mean 16.9 % SL) .................................................................................. B. vibex

10 Caudal fin with well developed ocellus on dorsal lobe .............................................. 11

- Caudal fin pigmented but lacking a well formed ocellus ............................................ 12

11 Caudal fin with almost symmetrical well-formed ocelli on both lobes .......... B. affinis

- Caudal fin with only a single, well-formed ocellus on the dorsal lobe .... B. giacopinii

12 Caudal fin with prominent black stripe, width almost equal to the pupil, asymmetrically from the central fin rays onto the dorsal lobe; remainder of fin clear to lightly pigmented and with dusky margin. Outer teeth on premaxilla 3-6, modally 4. Precaudal vertebrae 17-18. Anal fin originates under 17th -18th centrum ........ B. melanurus

- Darkened central caudal rays not principal pigment pattern on fin; wide stripe absent. In life, caudal fin either completely blackened or carmine red with dusky posterior margin. In preservation, caudal fin with black striations along all fin rays. Outer teeth on premaxilla 4-6, modally 5. Precaudal vertebrae 18-20. Anal fin originates under 19th -20th centrum, rarely 18th centrum ..................................................................... 13

13 Caudal fin principally black with some red suffused among outer 3-4 principal rays of both lobes. Anal fin with broad prominent black stripe along entire base of fin. Cheek with conspicuous blotch of pigment. Lower lobe of caudal fin longer than upper lobe .................................................................................................................... B. colanegra

- Caudal fin completely carmine red. Anal fin with pigment along fin rays, not in membranes, not forming prominent wide stripe along entire length of fin. Cheek lacking conspicuous blotch of pigment. Upper lobe of caudal fin longer than lower lobe ... 14

14 Circumdorsal scales 14-16, modally 15. Maxilla reaching articulation of second and third infraorbitals. Third infraorbital contacting preopercle at angle.......... B. colaroja

- Circumdorsal scales 17-19, modally 17. Maxilla not reaching articulation of second and third infraorbitals. Third infraorbital not contacting preopercle at angle ............... ........................................................................................................................ B. imitator

  • Barry Chernoff, Antonio Machado-Allison (2005): Bryconops magoi and Bryconops collettei (Characiformes: Characidae), two new freshwater fish species from Venezuela, with comments on B. caudomaculatus (Gunther). Zootaxa 1094, 1-23: 20-22, URL:http://www.zoobank.org/urn:lsid:zoobank.org:pub:2847B8DC-ED42-4562-9EF6-A4E8DC5F59A0
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Ecology

Habitat

Depth range based on 7 specimens in 1 taxon.

Environmental ranges
  Depth range (m): 0.6 - 1.5

Graphical representation

Depth range (m): 0.6 - 1.5
 
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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage

Barcode of Life Data Systems (BOLD) Stats
Specimen Records: 29
Specimens with Sequences: 27
Specimens with Barcodes: 27
Species: 6
Species With Barcodes: 5
Public Records: 5
Public Species: 2
Public BINs: 2
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Barcode data

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Wikipedia

Bryconops

Bryconops is a genus of South American freshwater fish of the family Characidae. They are commonly known as saltadores ("jumpers"). They usually live in clear and acidic waters.

Species[edit]

References[edit]

Further reading[edit]

  • Chernoff, B. & A. Machado-Allison (1997). Bryconops disruptus (Characiformes-Characidae, una nueva especie de pez de la cuenca del Río Negro en Brasil y Venezuela. Acta Biologica Venezuelica, 17(2):67-75.
  • Chernoff, B. & A. Machado-Allison (1999). Bryconops colaroja and B. colanegra, two new species from the Cuyuni and Caroni drainages of South America. Ichth. Explor. Freshwaters, Vol. 10(4): 355-370.
  • Chernoff, Barry & Machado-Allison, Antonio (2005). "Bryconops magoi and Bryconops collettei (Characiformes: Characidae), two new freshwater fish species from Venezuela, with comments on B. caudomaculatus (Günther)". Zootaxa 1094: 1–23.  Includes a key.
  • Chernoff, B, A. Machado-Allison, P. Buckup & R. Royero (1994). Systematic status and neotype designation for Autanichthys giacopinni Fernandez-Yepez, with comments on the morphology of Bryconops melanurus (Bloch). Copeia, 1:238-242.
  • Chernoff,B. A. Machado-Allison, F. Provenzano, P. Willink & P. Petry (2002). Bryconops imitator a new species of freshwater fish from the Rio Caura, Venezuela. Icht. Explor. Freshwaters, 13 (3): 193-202
  • Machado-Allison, A., B. Chernoff, P. Buckup & R. Royero (1993). Las especies de Género Bryconops Kner, 1858 en Venezuela (Teleostei, Characiformes). Acta Biologica Venezuelica, 14(3):1-20.
  • Machado-Allison, A., B. Chernoff y P. Buckup (1996). Bryconops humeralis y B. vibex, dos nuevas especies del Género Bryconops Kner, 1858 para Venezuela. Acta Biologica Venezuelica, 16(2):43-58.


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