Bryconops humeralis
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Characiformes
Family: Iguanodectidae
Genus: Bryconops
Species:
B. humeralis
Binomial name
Bryconops humeralis
Chernoff & Machado-Allison, 1996

Bryconops humeralis is a small freshwater fish distributed across northern South America. The name "humeralis" means "relating to the shoulder" (to the humerus), in reference to the distinct humeral patches that the fish sports. It is slightly longer than average in terms of the genus Bryconops, though still firmly within the standard range, and is slightly more slender than is usual for its congeners.

Along with Bryconops vibex, B. humeralis was described by Barry Chernoff & Antonio Machado-Allison in 1996 from the Orinoco River Basin in Venezuela. It is known to be an invertivore - that is, primarily consuming invertebrates (largely insects).

Description

Bryconops humeralis reaches a maximum of roughly 8.6 cm (3.4 in) in standard length,[1] though averages closer to 7.5 cm (3.0 in).[2] In comparison to other members of Bryconops, it is close to the middle of the size range, if slightly above in larger specimens.[3] Its body is on the shallow side, which can help differentiate it from several of its congeners.[4] Its scales are largely silvery in color, its fins are dark-tinted but translucent, and the dorsal half of its caudal fin sports an orange or yellowish ocellus (eyespot).[5]

The specific epithet originates from the presence of a distinct humeral patch near each of B. humeralis's pectoral fins, which are its main distinguishing trait.[6] This is a marking it shares with a few of its congeners, but other features can be used to tell them apart; for instance, B. inpai and B. munduruku have a pair of humeral marks by each fin as opposed to just one in B. humeralis.[7] B. vibex and B. marabaixo have single humeral patches (as opposed to paired), but other features distinguish them from B. humeralis, such as number of scales beneath the lateral line (B. humeralis has fewer than B. vibex)[5] and body shape (B. marabaixo has a deeper body than B. humeralis, more reminiscent of B. inpai).[4]

Classification

Bryconops humeralis has retained its designation as a member of Bryconops since its description in 1996.[8] The genus Bryconops has two subgenera, Bryconops and Creatochanes, and B. humeralis is considered a member of Creatochanes, which makes its full name Bryconops (Creatochanes) humeralis.[7] This sub-classification is based on the fact that it has at least one maxillary tooth on both sides of the mouth, which is the main characterizing facet of Creatochanes.[9]

Bryconops and its sister genera Piabucus and Iguanodectes are considered members of the relatively recent family Iguanodectidae, which was named in research by Oliveria et al. (2011).[10] As a result, some resources (such as ITIS and ADW)[11][12] still list B. humeralis as a member of the family Characidae, which is where Bryconops was previously classified. Nonetheless, its modern placement is with the rest of Bryconops (under Iguanodectidae).[13][14]

Distribution and ecology

Like other members of its genus, B. humeralis is found solely in northern South America. It was first recognized from the Orinoco Basin in Venezuela, and its range has since been established as encompassing the Orinoco, Negro, and Casiquiare rivers.[1][8] Its affinity for blackwater habitats, such as the Rio Negro, indicates that it does not have high-oxygen needs; this is because blackwater habitats are low in oxygen, as microbes consume all available dissolved oxygen in the water.[15] (Microbial decay is responsible for blackwater conditions; the breakdown of organic material releases trapped tannins into the environment.)[16]

Though extensive research has not been performed on B. humeralis's diet, it is known to prey on invertebrates. This is a similarity it shares with most other species of Bryconops (though some are documented herbivores).[2]

Bryconops humeralis has not been evaluated by the IUCN.[1]

References

  1. 1 2 3 Froese, Rainer; Pauly, Daniel (eds.) (2022). "Bryconops humeralis" in FishBase. October 2022 version.
  2. 1 2 Echevarría, Gabriela; González, Nirson (November 2018). "Fish taxonomic and functional diversity in mesohabitats of the River Kakada, Caura National Park, Venezuela". Nature Conservation Research. 3 (Suppl. 2). doi:10.24189/ncr.2018.048. Retrieved 4 October 2022.
  3. ↑ Froese, Rainer and Pauly, Daniel, eds. (2022). Species of Bryconops in FishBase. October 2022 version.
  4. 1 2 Silva‐Oliveira, Cárlison; Moreira, Cristiano R.; Lima, Flávio C. T.; Py‐Daniel, Lúcia Rapp (September 2020). "The true identity of Bryconops cyrtogaster ( Norman ), and description of a new species of Bryconops Kner ( Characiformes: Iguanodectidae ) from the Rio Jari , lower Amazon basin". Journal of Fish Biology. 97 (3): 860–868. doi:10.1111/jfb.14445. PMID 32584438. S2CID 220060299. Retrieved 5 October 2022.
  5. 1 2 Chernoff, Barry; Machado-Allison, Antonio (31 December 2005). "Bryconops". doi:10.5281/zenodo.6265593. {{cite journal}}: Cite journal requires |journal= (help)
  6. ↑ Scharpf, Christopher; Lazara, Kenneth J. (15 September 2020). "Order CHARACIFORMES: Families IGUANODECTIDAE, TRIPORTHEIDAE, BRYCONIDAE, CHALCEIDAE and GASTEROPELECIDAE". The ETYFish Project. Retrieved 4 October 2022.
  7. 1 2 Silva-Oliveira, Cárlison; Canto, André Luiz C.; Ribeiro, Frank Raynner V. (30 July 2015). "Bryconops munduruku (Characiformes: Characidae), a new species of fish from the lower Tapajós River basin, Brazil". Zootaxa. 3994 (1): 133–141. doi:10.11646/zootaxa.3994.1.7. PMID 26250264 – via Biotaxa.
  8. 1 2 Machado Allison, Antonio; Chernoff, Barry; Buckup, Paulo (1996). "Bryconops humeralis y B.vibex, dos nuevas especies del genero bryconops kner (1858) para Venezuela". Acta Biologica Venezuela (in Spanish). 16 (2): 45–58. Retrieved 5 October 2022.
  9. ↑ 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 4 October 2022.
  10. ↑ Oliveira, Claudio; Avelino, Gleisy S.; Abe, Kelly T.; Mariguela, Tatiane C.; Benine, Ricardo C.; Ortí, Guillermo; Vari, Richard P.; Corrêa e Castro, Ricardo M. (December 2011). "Phylogenetic relationships within the speciose family Characidae (Teleostei: Ostariophysi: Characiformes) based on multilocus analysis and extensive ingroup sampling". BMC Evolutionary Biology. 11 (1): 275. doi:10.1186/1471-2148-11-275. PMC 3190395. PMID 21943181.
  11. ↑ "Bryconops humeralis Machado-Allison, Chernoff and Buckup, 1996". Integrated Taxonomic Information System. Retrieved 5 October 2022.
  12. ↑ Myers, P.; Espinosa, R.; Parr, C. S.; Jones, T.; Hammond, G. S.; Dewey, T. A. "Bryconops humeralis Classification". Animal Diversity Web. University of Michigan Museum of Zoology. Retrieved 5 October 2022.
  13. ↑ Rees, Tony (31 December 2011). "IRMNG - Bryconops humeralis Machado-Allison, Chernoff & Buckup, 1996". International Register of Marine and Nonmarine Genera. Retrieved 4 October 2022.
  14. ↑ Bailly, Nicolas (6 July 2017). "WoRMS taxon details - Bryconops humeralis Machado-Allison, Chernoff & Buckup, 1996". World Register of Marine Species. Retrieved 5 October 2022.
  15. ↑ Mehring, Andrew S.; Kuehn, Kevin A.; Tant, Cynthia J.; Pringle, Catherine M.; Lowrance, R. Richard; Vellidis, George (2014). "Contribution of surface leaf-litter breakdown and forest composition to benthic oxygen demand and ecosystem respiration in a South Georgia blackwater river". Freshwater Science. 33 (2): 377–389. doi:10.1086/675507. S2CID 85315129. Retrieved 18 May 2022.
  16. ↑ "Hypoxic blackwater events and water quality". Department of Agriculture, Water and the Environment. Australian Government. 2016. Retrieved 18 May 2022.
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