Bryconops durbinae explained

Bryconops durbinae, sometimes listed under the name Bryconops durbini, is a small species of freshwater fish in the family Iguanodectidae. It is the smallest species of the genus Bryconops, and is endemic to the Tapajós river basin in Brazil.

Description

Bryconops durbinae is small and slender, with a large mouth in comparison to the body.[1] It is the smallest member of the genus Bryconops at 3.1 cm (1.2 in) in standard length; the second-smallest is Bryconops disruptus, at 6.4 cm (2.5 in). Its fins are generally hyaline (transparent), though it does bear a caudal ocellus (eyespot on the tail) that is transparent when preserved in alcohol, but ranges from red to yellow in life.[2] Its caudal fin is darker than the rest, which makes said ocellus more obvious upon examination.

In terms of body coloration, Bryconops durbinae is generally an iridescent silver, with a black lateral stripe down each side underlined by a silver stripe. The lateral line, however, is regularly incomplete;[3] this is a similarity it shares with congener Bryconops disruptus. They are relatively easy to tell apart because the lateral line of B. disruptus has fewer pored scales, ranging wildly from 9 to 23,[4] whereas B. durbinae has around 30 pored lateral line scales at a minimum.

Reportedly, the small size and incomplete lateral line give Bryconops durbinae an incredibly similar appearance to the juveniles of congener Bryconops caudomaculatus. One of the only ways to tell the two apart is that juvenile specimens of B. caudomaculatus have not developed teeth on their maxillaries. This is in contrast to adult specimens of B. durbinae, which have maxillaries equipped with at least two teeth on each side, the outer set multicuspid and the inner set conical.

Taxonomy

When first described by German-American ichthyologist Carl H. Eigenmann in 1908, Bryconops durbinae was named Brycochandus durbini. This established Brycochandus as a monotypic genus, but Brycochandus was later synonymized with Bryconops.[5] Knöppel et al. noted B. durbinae's similarity to members of the genus Creatochanes, which was also later synonymized with Bryconops (though now accepted as a subgenus).[6] [7]

There are two subgenera in the genus Bryconops, Bryconops and Creatochanes. Bryconops durbinae is one of eight species that belong to the subgenus Bryconops, making its full scientific name Bryconops (Bryconops) durbinae.[8] Other members are species that all share notable visual similarities, including B. caudomaculatus and B. disruptus (both mentioned prior).

Prior to 2011, Bryconops was considered a member of the family Characidae, but research in said year moved it to the family Iguanodectidae, along with the genera Piabucus and Iguanodectes.[9]

Etymology

Though Bryconops durbinae is listed under that name by many authorities,[10] and is referred to as such in most modern publications,[11] [12] it is also easily found under the name Bryconops durbini, a spelling that more closely resembles its baisonym.[13] [14] [15] The origin of the specific epithet in question is limnologist and environmental toxicologist Marion Durbin Ellis, a student of Eigenmann's.[16] B. durbinae lacks an accepted common name, but "Durbin's tetra" has been suggested as an etymological result of the specific epithet.

Habitat and ecology

Bryconops durbinae is known only from the Rio Tapajos in Brazil. This has been the case since it was described.[17] The Rio Tapajos is a somewhat acidic clearwater river, with a pH that ranges from 4.5 to 7.8.[18] Most of the time, the water carries very little sediment.[19]

This preference for an acidic environment is something shared with various members of the genus Bryconops, but several of them - like B. caudomaculatus,[20] B. disruptus, and B. colaroja[21] - are found in blackwater rather than clearwater habitats. Bryconops collettei is a congener that inhabits both black and clear waters.

Conservation status

Bryconops durbinae has not been evaluated by the IUCN. Nonetheless, it faces threats to its population, mostly in the form of human activity and environmental destruction (which is also the case for the species of Bryconops that have been evaluated).[22]

The Rio Tapajos has long been considered for possible infrastructure development and mining operations,[23] and there have been instances of illegal mining disturbing enough sediment to turn the water completely brown. The region is of great importance to not only ecological biodiversity but also to a population of roughly 1.4 million people, including various indigenous tribes,[24] and so legal plans and operations have been reconsidered in the context of having as little impact on the region as possible. Therefore, Bryconops durbinae (alongside the other Tapajos-endemic species) has a greater chance for survival.

Notes and References

  1. Eigenmann . Carl H. . 1908 . Preliminary descriptions of new genera and species of tetragonopterid characins (Zoölogical Results of the Thayer Brazilian expedition.) . Bulletin of the Museum of Comparative Zoology . 52 . 6 . 91–106 . 10 May 2022.
  2. Book: Eigenmann . Carl H. . The American Characidae . Meyers . George S. . 1917–1929 . Cambridge . 433–434 . 10 May 2022.
  3. Knöppel . Hans-Armin . Junk . Wolfgang . Géry . Jacques . January 1968 . Bryconops (Creatochanes) inpai, a new characoid fish from the Central Amazon Region, with a review of the genus Bryconops . Amazoniana . 1 . 3 . 231–246 . 202183505 .
  4. Guedes . Tharles L. O. . Oliveira . Everton F. . Lucinda . Paulo H. F. . 14 March 2016 . A new species of Bryconops (Ostariophysi: Characiformes: Characidae) from the upper rio Tocantins drainage, Brazil . Neotropical Ichthyology . 14 . 2 . 10.1590/1982-0224-20150176 . free .
  5. Web site: Brycochandus Eigenmann, 1908 . 10 May 2022 . World Register of Marine Species.
  6. Web site: Creatochanes Günther, 1864 . 10 May 2022 . World Register of Marine Species.
  7. Wingert . Juliana Mariani . Malabarba . Luiz Roberto . 4 April 2011 . Descrição de duas novas espécies de Bryconops (Teleostei: Characidae) da Bacia do Rio Amazonas . 10183/28524 . 10 May 2022.
  8. 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 . 10.11646/zootaxa.3994.1.7 . 26250264 . 10 May 2022 . Biotaxa.
  9. 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 . 10.1186/1471-2148-11-275 . 21943181 . 3190395 . free .
  10. Web site: Bryconops durbinae (Eigenmann, 1908) . 10 May 2022 . World Register of Marine Species.
  11. Silva-Oliveira . Cárlison . Ota . Rafaela P. . Sabaj . Mark H. . Py-Daniel . Lúcia H. Rapp . 13 December 2021 . A new species of Bryconops (Characiformes: Iguanodectidae) from Atlantic coastal drainages of Suriname and French Guiana . Neotropical Ichthyology . en . 19 . 4 . 10.1590/1982-0224-2021-0113 . 245224953 . 1679-6225 . free .
  12. Silva-Oliveira . Cárlison . Ota . Rafaela P. . Lima . Flávio C. T. . Py-Daniel . Lúcia Rapp . 13 December 2021 . Rediscovering species: redescription of Bryconops gracilis (Characiformes: Iguanodectidae), an often-misidentified species . Neotropical Ichthyology . 19 . 4 . 10.1590/1982-0224-2021-0054 . 245251694 . free .
  13. Web site: Bryconops durbini (Eigenmann 1908) Names . 10 May 2022 . Encyclopedia of Life.
  14. Web site: Bryconops durbini (Eigenmann, 1908) . 10 May 2022 . Integrated Taxonomic Information System.
  15. Web site: Bryconops durbini (Eigenmann, 1908) . 10 May 2022 . GBIF . Global Biodiversity Information System.
  16. Web site: Scharpf . Christopher . Lazara . Kenneth J. . 15 September 2020 . Order CHARACIFORMES: Families IGUANODECTIDAE, TRIPORTHEIDAE, BRYCONIDAE, CHALCEIDAE and GASTEROPELECIDAE . 10 May 2022 . The ETYFish Project.
  17. Eigenmann . Carl H. . 1910 . Catalogue of the fresh-water fishes of tropical and south temperate America . Reports of the Princeton University Expeditions to Patagonia, 1896-1899 . 3 . 2 . 435 . 10 May 2022.
  18. Web site: Petry . Paulo . Hales . Jennifer . Tapajos - Juruena . 10 May 2022 . Freshwater Ecoregions of the World.
  19. Web site: Amazon, Tapajós, and Santarém . 10 May 2022 . Earth Observatory . 2 November 2015 . Nasa.
  20. Machado-Allison, Antonio . Buckup, Paulo . Chernoff, Barry . Royero, Ramiro . March 1993 . Las especies del genero Bryconops Kner, 1858 en Venezuela (Teleostei, Characiformes) . Acta Biologica Venezuelica . 14 . 3 . 1–20 . 10 May 2022.
  21. 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 . 10872/17856 . 10 May 2022.
  22. Web site: Search for "Bryconops" . 10 May 2022 . IUCN Red List . International Union for the Conservation of Nature.
  23. News: Bradford . Sue . 26 August 2016 . Planned Tapajós industrial waterway a potential environmental disaster . Mongabay News . 10 May 2022.
  24. News: 6 November 2018 . The Tapajos River: Hope for Sustainable Development . The Nature Conservancy . The Nature Conservancy . 10 May 2022.

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