Deuterodon sazimai
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Characiformes
Family: Characidae
Genus: Deuterodon
Species:
D. sazimai
Binomial name
Deuterodon sazimai
Santos & Castro, 2014
Synonyms[1]

Probolodus sazimai (Santos & Castro, 2014)

Deuterodon sazimai is a small freshwater fish endemic to a handful of river basins in southeastern Brazil. Upon being first described, it was considered a member of genus Probolodus; Probolodus is now considered obsolete, synonymized with Deuterodon. Much like other members of Deuterodon, and like some species in related genera like Astyanax or Jupiaba, D. oyakawai is a silvery fish with fins in some combination of red and clear. It sports a wedge-shaped humeral spot, and an oval-shaped blotch on its tail joint.

This species demonstrates lepidophagy, or scale-eating, which is not uncommon in closely related congeners. Its most likely targets include other members of Deuterodon. Its diet is occasionally supplemented by leaves and insects, though these are rare additions. Further details, regarding aspects such as behavior and biotope preferences, are sparse.

Taxonomy

Deuterodon sazimai was originally described as Probolodus sazimai upon nomination by a Brazilian research team in 2014. Some databases, such as GBIF[2] and the Encyclopedia of Life,[3] still list it as a member of Probolodus. However, the genera Probolodus and Myxiops were synonymized with Deuterodon as part of a 2020 study that closely examined the phylogeny of Astyanax and related groups, such as Psalidodon, Andromakhe, Makunaima, and Deuterodon itself.[4] This updated classification is reflected in databases like FishBase,[5] the World Register of Marine Species,[6] and Eschmeyer's Catalog of Fishes.[7]

Etymology

The genus name "Deuterodon" is Greek. It comes from "deuteros", which means "second" or "repeated", and "odon", which means "tooth"; this is in reference to the similarity of all teeth in the lower jaw. The specific name "sazimai" honors Ivan Sazima, an ichthyologist from the Museu de Zoologia, Universidade Estadual de Campinas of São Paulo, Brazil. Sazima is notable for contributions to the knowledge of neotropical lepidophagous characiform fishes.[8]

Description

Deuterodon sazimai is a small fish, reaching a maximum of 5.7 cm (2.2 in) SL (standard length, with the tail fin left out of the measurement).[5] The body is somewhat compressed and deep; this is more evident in smaller specimens, and body depth can vary between populations, though there is significant overlap between those located near each other. The lateral line has 36–43 pored scales, which can be used to differentiate it from congeners; D. heterostomus, for instance, has 45–56 scales therein.[9] There are 11 dorsal-fin rays, 26–32 anal-fin rays, 12–13 pectoral-fin rays, 7–8 ventral-fin rays, and 19 caudal-fin rays.[10]

The coloration in life is generally similar to relatives such as Deuterodon heterostomus and Deuterodon oyakawai, with a base silver and fins that are reddish or clear. When preserved in alcohol, the base color changes to a yellowish-brown, with some remaining silver due to guanine. The back darkens to a brownish color because of the chromatophores concentrated in the middle and base of the scales (lacking at the margins), and the body remains pale below the lateral line. There is a large, wedge-shaped humeral spot, and a dark lateral stripe that leads to another blotch of pigment on the caudal peduncle, shaped like a horizontal oval.[11]

Sexual dimorphism

Large, mature males may develop backwards-facing bony hooks on some rays of the anal fin.[11]

Distribution and ecology

Deuterodon sazimai is known to occur in the basins of the Itapemirim and Doce rivers, which are located in the Espírito Santo and Minas Gerais states of southeastern Brazil, respectively.[10]

The Itapemirim river flows from west to east for roughly 320 km (200 mi), encompassing a drainage area of about 6,014 km2.[12] The Doce river basin is located further north along the Atlantic coastline, and flows for about 853 km (530 mi); the ecosystem therein is considered sensitive to climate variability.[13]

Diet

The diet of D. sazimai is almost entirely made up of scales from other fish, which have been found extensively in the stomach contents of examined specimens. This is a specialized feeding behavior known as lepidophagy. Other dietary contributors, much less prevalent than scales, have been found in the mouths of preserved specimens on occasion; these include leaf fragments and insects.[11]

Conservation status

Deuterodon sazimai does not have a conservation status from the IUCN.[5] It is a widespread species, which increases survivability, but it currently inhabits regions known to be the subject of pollution; for example, the Doce River suffered the Mariana dam disaster, a catastrophic dam collapse, in 2015. This event released 43.7 million cubic meters of mine tailings into the Doce River, and the resultant toxic mudflow polluted the river and beaches for years afterwards.[14] The Itapemirim also faces anthropogenic survival pressures, including contamination by aluminum and copper. Fish and plants near the river have been recorded in notably worse health as a result of metal toxicity, and the water quality of the river overall is considered to be suboptimal.[15]

References

  1. ↑ Bailly, Nicholas (2014). "Probolodus (Eigenmann, 1911)". WoRMS. World Register of Marine Species. Retrieved 24 Oct 2023.
  2. ↑ "Probolodus sazimai (Santos & Castro, 2014)". Global Biodiversity Information Facility. Retrieved 24 October 2023.
  3. ↑ "Probolodus sazimai (Santos & Castro, 2014)". Encyclopedia of Life. National Museum of Natural History. Retrieved 24 October 2023.
  4. ↑ Terán, Guillermo E; Benitez, Mauricio F; Mirande, J Marcos (11 April 2020). "Opening the Trojan horse: phylogeny of Astyanax, two new genera and resurrection of Psalidodon (Teleostei: Characidae)". Zoological Journal of the Linnean Society. doi:10.1093/zoolinnean/zlaa019.
  5. 1 2 3 Froese, Rainer; Pauly, Daniel (eds.) (2023). "Deuterodon sazimai" in FishBase. October 2023 version.
  6. ↑ Bailly, Nicholas (2022). "Deuterodon sazimai (Santos & Castro, 2014)". WoRMS. World Register of Marine Species.
  7. ↑ Eschmeyer, William N.; Fricke, Ron & van der Laan, Richard (eds.). "Species related to Probolodus sazimai". Catalog of Fishes. California Academy of Sciences. Retrieved 25 October 2023.
  8. ↑ Scharpf, Christopher; Lazara, Kenneth J. (29 December 2022). "Order CHARACIFORMES: Family CHARACIDAE: Subfamily STETHAPRIONINAE (a-g)". The ETYFish Project. Retrieved 25 October 2023.
  9. ↑ "Probolodus sazimai Santos & Castro, 2014". treatment.plazi.org. Plazi TreatmentBank. Retrieved 26 October 2023.
  10. 1 2 Santos, Osmar; Castro, Ricardo M. C. (30 June 2014). "Treatment for Probolodus sazimai Santos & Castro 2014, new species". doi:10.5281/zenodo.5137673. {{cite journal}}: Cite journal requires |journal= (help)
  11. 1 2 3 Santos, Osmar; Castro, Ricardo M. C. (June 2014). "Taxonomy of Probolodus Eigenmann, 1911 (Characiformes: Characidae) with description of two new species, and comments about the phylogenetic relationships and biogeography of the genus". Neotropical Ichthyology. 12 (2): 403–418. doi:10.1590/1982-0224-20130232.
  12. ↑ Gonçalves, José Augusto Costa; Almeida, Milena Stefany Lage; Vieira, Eliane Maria; Paiva, Brenda Luiza Ferreira; Ferreira, Mariana Araújo Mendes; Marcellino, Lázaro Correa (2 January 2023). "Interaction Between Surface and Underground Waters of the Itapemirim and Itabapoana River Basins in the Southern part of the State of Espírito Santo, Southeastern Brazil". Anuário do Instituto de Geociências. 46. doi:10.11137/1982-3908_2023_46_49992.
  13. ↑ Arndt, Iris; Voigt, Silke; Petschick, Rainer; Hou, Alicia; Raddatz, Jacek; Albuquerque, Ana Luiza S.; Bahr, André (6 June 2022). "Spatiotemporal Discharge Variability of the Doce River in SE Brazil During MIS 6 and 5". Frontiers in Earth Science. 10. doi:10.3389/feart.2022.864381.
  14. ↑ Gabriel, Fabrício Â.; Ferreira, Amanda D.; Queiroz, Hermano M.; Vasconcelos, Ana Luisa S.; Ferreira, Tiago O.; Bernardino, Angelo F. (October 2021). "Long-term contamination of the Rio Doce estuary as a result of Brazil's largest environmental disaster". Perspectives in Ecology and Conservation. 19 (4): 417–428. doi:10.1016/j.pecon.2021.09.001.
  15. ↑ Galter, Iasmini Nicoli; Duarte, Ian Drumond; Malini, Maressa; Aragão, Francielen Barroso; de Oliveira Martins, Ian; Rocha, Lívia Dorch; Carneiro, Maria Tereza Weitzel Dias; do Espírito Santo, Kamila Soares; de Oliveira David, José Augusto; Matsumoto, e Silvia Tamie (February 2021). "Water assessment of the Itapemirim River/Espírito Santo (Brazil): abiotic and toxicogenetic aspects". Environmental Science and Pollution Research. 28 (8): 10175–10191. doi:10.1007/s11356-020-11116-0.
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