Bryconops colanegra

Bryconops colanegra is a small, slender-bodied species of freshwater fish from South America, about 3.5 in (8.8 cm) long. It has a black tail fin that bears hints of red, and its scales are dark along the back, transitioning to a silver belly. It is native to a single river system in Venezuela, the Rio Caroní.

Bryconops colanegra
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Characiformes
Family: Iguanodectidae
Genus: Bryconops
Species:
B. colanegra
Binomial name
Bryconops colanegra
Chernoff & Machado-Allison, 1999

Description

Bryconops colanegra is one of the smaller members of the genus Bryconops, at 8.8 cm (3.5 in) standard length.[1] It has dark back scales that fade to a silvery belly, aside from a patch in the opercular and cheek region that bears definite pigmentation (something that also appears in congener B. melanurus).[2] The anal fin has a broad band of black along the base, which is a feature that B. colanegra does not share with any other members of the genus.[3]

The distinct black caudal fin that Bryconops colanegra has is the origin of its scientific name: "cola-" means "tail", and "negra" means "black".[4] This is one way to differentiate it from several congeners. B. colaroja, for example, has a red caudal fin, and the tailspot tetra (B. caudomaculatus) has a large, distinct spot on its tail. Though its pigmentation is its main feature, there is usually a hint of red in the caudal fin nonetheless.[2]

The teeth are multicuspid, and the fish is equipped with a set of gill rakers that are notably denticulated - that is, covered in tooth-like protrusions.[2] The higher denticulation level is in contrast with congener B. colaroja, whose gill rakers have fewer protrusions. Multicuspid teeth are a feature that the genus Bryconops shares with sister clade Iguanodectinae.[5]

Taxonomy

Described in 1999,[6] Bryconops colanegra belongs to the subgenus Creatochanes, making its full scientific name Bryconops (Creatochanes) colanegra.[2] In the same study that elevated it to species status, its congener B. colaroja was also named.[2] Though it has a scientific name that means "black tail", B. colanegra does not have an accepted common name.[7] The name "black-tailed tetra" has been suggested.

Bryconops colanegra used to be considered a characin, or a member of the family Characidae. However, research in 2011 prompted that the genus Bryconops, along with the genera Iguanodectes and Piabucus, be moved to the family Iguanodectidae.[8] Subsequently, B. colanegra's current accepted classification is as an Iguanodectid fish.[9] It remains a member of the order Characiformes.

Habitat and ecology

Bryconops colanegra is found largely in the Caroní River, which stretches across Venezuela (not to be confused with the Caroni River in Trinidad and Tobago).[10][11] The Caroní, as a blackwater river, has a high concentration of humic substances. Because microbial activity is what causes blackwater conditions, blackwater rivers are poorly oxygenated (with microbes taking up whatever oxygen they can), indicating that B. colanegra does not need oxygen-rich water to survive.[12]

Conservation status

Because the Caroní River is facing construction of several hydroelectric dams and already provides 70% of Venezuela's hydroelectric power, the ecology of the region faces repercussions, possibly severe.[13] The local ecosystems are also threatened by current mining projects, various types of which have been occurring in the region since the 1990s.[14] As it currently stands, however, B. colanegra is considered a species of least concern on the IUCN Red List, based upon a wide native range - the Caroní is the longest single river in Venezuela.[15]

Bryconops colanegra is known to be taken from the wild for the aquarium industry. Its trade is not restricted nor blocked in any country, and it is not in widespread use as a captive animal.[16] Capture from the wild is also not considered a threat to its population numbers; its greatest threat is perhaps habitat disruption by way of human activity.[15] This is something it shares with other members of the genus that have been evaluated.[17]

Diet

Though little of B. colanegra's diet specifically has been studied, other members of the genus are known to be insectivorous, displaying differing preferences for invertebrates from various habitats. For example, the tailspot tetra (B. caudomaculatus) is known to jump out of the water to catch flying insects, while B. alburnoides demonstrates a taste for terrestrial insects.[18][19] The orangefin tetra, B. affinis, makes plants a more prominent part of its diet.[20] It can reasonably be assumed that B. colanegra's diet is similar to those of its congeners.

References
  1. Froese, Rainer; Pauly, Daniel (eds.) (2022). "Bryconops colanegra" in FishBase. April 2022 version.
  2. Chernoff, Barry; Machado-Allison, Antonio (23 February 2018). "Bryconops colaroja and B. colanegra, two new species from the Cuyuni and Caroni drainages of South America (Teleostei: Characidae)". Ichthyological Exploration of Freshwaters. 10 (4): 355–370. hdl:10872/17856. Retrieved 10 April 2022.
  3. Chernoff, Barry; Machado-Allison, Antonio (13 December 2005). "Bryconops magoi and Bryconops collettei (Characiformes: Characidae), two new freshwater fish species from Venezuela, with comments on B. caudomaculatus (Günther)". Zootaxa. 1094 (1): 1. doi:10.11646/zootaxa.1094.1.1. Retrieved 10 April 2022.
  4. Scharpf, Christopher; Lazara, Kenneth J. (15 September 2020). "Order CHARACIFORMES: Families IGUANODECTIDAE, TRIPORTHEIDAE, BRYCONIDAE, CHALCEIDAE and GASTEROPELECIDAE". The ETYFish Project. Retrieved 6 April 2022.
  5. Vari, Richard P. (26 January 1977). "Notes on the characoid subfamily Iguanodectinae, with a description of a new species". American Museum Novitates (2612). hdl:2246/2012 – via AMNH Digital Repository.
  6. "Bryconops colanegra Chernoff & Machado-Allison, 1999". Global Biodiversity Information Facility. Retrieved 10 April 2022.
  7. "Bryconops colanegra Chernoff & Machado-Allison (1999) Names". Encyclopedia of Life. Retrieved 10 April 2022.
  8. Oliveira, C., Avelino, G.S., Abe, K.T. et al. ()26 September 2011). Phylogenetic relationships within the speciose family Characidae (Teleostei: Ostariophysi: Characiformes) based on multilocus analysis and extensive ingroup sampling. BMC Evol Biol. 11(275). https://doi.org/10.1186/1471-2148-11-275. Retrieved 10 April 2022.
  9. "Bryconops colanegra Chernoff & Machado-Allison, 1999". World Register of Marine Species. Retrieved 10 April 2022.
  10. Petry, Paulo; Hales, Jennifer. "Orinoco Guiana Shield". Freshwater Ecoregions of the World. Retrieved 10 April 2022.
  11. Reis, R.E.; Kullander, S.O.; Ferraris, C.J. (2003). Check List of the Freshwater Fishes of South and Central America. EDIPUCRS. p. 119. ISBN 8574303615. Retrieved 10 April 2022.
  12. "Hypoxic blackwater events and water quality". Department of Agriculture, Water and the Environment. Australian Government. 2016. Retrieved 10 April 2022.
  13. "South America: Southern Venezuela, northern Brazil, western Guyana, and eastern Colombia". World Wildlife Fund. Retrieved 10 April 2022.
  14. Leotaud, Valentina Ruiz (22 April 2020). "Venezuela allows gold mining in river basins". Mining.com. Glacier Media. Retrieved 10 April 2022.
  15. Echevarría, G. (18 April 2017). "Bryconops colanegra: Echevarría, G.: The IUCN Red List of Threatened Species 2019: e.T118038855A118038861". IUCN Red List. International Union for the Conservation of Nature. doi:10.2305/IUCN.UK.2019-3.RLTS.T118038855A118038861.en. Retrieved 10 April 2022.
  16. Fredberg, Joshua; McNeil, Dale (August 2010). Review of non-native ornamental fish species grey listed in Australia (PDF). West Beach, SA: SARDI Aquatic Sciences. ISBN 978-1-921563-35-5. Retrieved 10 April 2022.
  17. "Search for "Bryconops"". IUCN Red List. International Union for the Conservation of Nature. Retrieved 10 April 2022.
  18. Costa-Pereira, Raul; Severo-Neto, Francisco (June 2012). "Dining out: Bryconops caudomaculatus jumps out of water to catch flies". Revista chilena de historia natural. 85 (2): 241–244. doi:10.4067/S0716-078X2012000200012. ISSN 0716-078X.
  19. da Silva, Cylene C.; Ferreira, Efrem J. G.; de Deus, Cláudia P. (28 June 2008). "Diet of Bryconops alburnoides and B. caudomaculatus (Osteichthyes: Characiformes) in the region affected by Balbina Hydroelectric Dam (Amazon drainage, Brazil)". Neotropical Ichthyology. 6 (2): 237–242. doi:10.1590/S1679-62252008000200011. Retrieved 10 April 2022.
  20. Froese, Rainer; Pauly, Daniel (eds.) (2022). "Bryconops affinis" in FishBase. April 2022 version.
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