Chalceus epakros

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Chalceus epakros
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Characiformes
Family: Chalceidae
Genus: Chalceus
Species:
C. epakros
Binomial name
Chalceus epakros

Chalceus epakros is a species of freshwater fish in the family Chalceidae, found in northern South America. It is a fairly recent addition to its genus, alongside the species C. guaporensis and C. spilogyros.

Description[edit]

Chalceus epakros bears visual similarities to other members of the genus Chalceus, like metallic scales and a vivid red or pink caudal fin, though several differences help separate it from its congeners. It has a thin stripe laterally that reaches the caudal peduncle, as well as a longer and more pointed snout.[1] It may occasionally bear humeral spots (a spot above each pectoral fin), but they are rather indistinct, especially compared to the humeral spots of C. spilogyros.[2] Its fins are a mixture of hyaline and reddish-pink, as opposed to the bright-yellow pelvic fins of C. erythrurus.[3]

Chalceus erythrurus and C. macrolepidotus may occasionally bear a similar lateral stripe to C. epakros, but theirs are broader and more indistinct.[2] It is hypothesized to be related to mating habits, and may be more prominent around mating season.[4] C. epakros' stripe is composed of chromatophores closer to the surface than that of C. erythrurus and others.[1]

Chalceus epakros is incredibly visually similar to C. guaporensis, including a thin lateral stripe, a pointed snout, and the occasional indistinct humeral patch.[4] C. epakros and C. guaporensis are also alike in that they lack a fontanel (soft, membranous spot) on the head, while the other three species have one between the frontal and parietal bone.[4] However, C. guaporensis is slightly larger, and it has 7 pelvic fin rays as opposed to eight on C. epakros.[2] C. epakros is the smallest Chalceus species, reaching 17.4 cm TL (with the caudal fin included); C. guaporensis reaches that same length in SL (without the caudal fin).[5]

Etymology[edit]

The specific name epakros is from Greek, and means "pointed at the end", in reference to the longer and more pointed snout;[1] compare Cryptocentrus epakros, the pointedfin shrimpgoby,

The genus name Chalceus comes from "chalkos", which is the Greek word for copper.[6] French biologist Georges Cuvier, who named the first member of Chalceus (C. macrolepidotus), named it this because the preserved specimen's scales were copper-colored ("sometimes golden") when preserved in alcohol, though its scales are silvery in life.[7][8]

Taxonomy[edit]

In the year 2004, Brazilian biologists Mônica Toledo-Piza and Angela M. Zanata performed a re-examination of the genus Chalceus, resulting in the nomination of not only C. epakros but its congeners C. guaporensis and C. spilogyros.[1] Upon study in 2005, C. epakros and C. guaporensis were determined to form a clade, accounting for their visual similarities, while C. spilogyros, C. erythrurus, and C. macrolepidotus share another.[4]

Previously, specimens of C. epakros had been misidentified as specimens of C. macrolepidotus and C. erythrurus; C. macrolepidotus (Cuvier) and C. erythrurus (Cope) are long-established members of the genus, having been named in 1818 and 1870, respectively.[9]

Habitat[edit]

Like the rest of its genus, C. epakros is a freshwater fish from northern South America.[10] C. epakros has the widest distribution of all Chalceus species, inhabiting the Amazon basin, the Orinoco river, and the Essequibo river.[1][6] Despite sharing a clade, C. epakros and C. guaporensis are not found in the same areas; this could either be due to competition between the species, or due to slight differences in environmental needs.[11]

Chalceus epakros and C. macrolepidotus are the only two Chalceus species known to occur in Guyana.[2]

Diet and behavior[edit]

Chalceus epakros seems to largely be an insectivore, targeting ants and wasps. In one study (Torrente-Vilara et al.), very few examined specimens had food material in their stomachs, making diet-mapping difficult.[11] This lines up with other, more thoroughly-studied Chalceus species, which target similar invertebrate spreads.[12][13]

Behaviorally, C. epakros is lacking in data. Other members of the genus are active, fast-moving, and somewhat skittish.[14][15]

References[edit]

  1. ^ a b c d e Zanata, A.M.; M. Toledo-Piza (2004). "Taxonomic revision of the South American fish genus Chalceus Cuvier (Teleostei: Ostariophysi: Characiformes) with the description of three new species". Zoological Journal of the Linnean Society. 140 (11): 103–135. doi:10.1111/j.1096-3642.2004.00090.x.
  2. ^ a b c d "Chalceus, Cuvier, 1817". Plazi TreatmentBank. Retrieved 27 December 2021.
  3. ^ Froese, Rainer; Pauly, Daniel (eds.) (2022). "Chalceus erythrurus" in FishBase. January 2022 version.
  4. ^ a b c d Zanata, Angela M. and Vari, Richard P. The family Alestidae (Ostariophysi, Characiformes): a phylogenetic analysis of a trans-Atlantic clade. Zoological Journal of the Linnean Society (2005).
  5. ^ Froese, Rainer and Pauly, Daniel, eds. (2021). Species of Chalceus in FishBase. December 2021 version.
  6. ^ a b Froese, Rainer; Pauly, Daniel (eds.) (2021). "Chalceus epakros" in FishBase. December 2021 version.
  7. ^ Scharpf, Christopher; Lazara, Kenneth J. (15 September 2020). "Order CHARACIFORMES: Families IGUANODECTIDAE, TRIPORTHEIDAE, BRYCONIDAE, CHALCEIDAE and GASTEROPELECIDAE". The ETYFish Project. Retrieved 31 December 2021.
  8. ^ Cuvier, Georges (1818). "Sur les Poissons du sous-genre Myletes". Mémoires du Muséum d'histoire naturelle. 4: 454. Retrieved 1 January 2022.
  9. ^ Reis, Roberto; Toledo-piza Ragazzo, Monica; Harold, Antony; Pavanelli, Carla; Buckup, Paulo A. (2003). "Genera incertae sedis in Characidae". Retrieved 27 December 2021. {{cite journal}}: Cite journal requires |journal= (help)
  10. ^ Fricke, Ron; Eschmeyer, William N. (2020). "Chalceus epakros". Eschmeyer's Catalog of Fishes. California Academy of Sciences. Retrieved 27 December 2021.
  11. ^ a b Torrente-Vilara, Gislene; Cella-Ribeiro, Ariana; Hauser, Marília; Röpke, Cristhiana; Freitas, Maria Helena; Doria, Carolina Rodrigues da Costa; Zuanon, Jansen (10 May 2018). "Spatial segregation between Chalceus guaporensis and Chalceus epakros (Osteichthyes: Characiformes) in the Madeira River, Amazon Basin". Acta Amazonica. 48 (3): 239–247. doi:10.1590/1809-4392201703022. ISSN 0044-5967. S2CID 91368802.
  12. ^ "Chalceus erythrurus (Tucanfish)". Seriously Fish. Retrieved 27 December 2021.
  13. ^ Froese, Rainer; Pauly, Daniel (eds.) (2021). "Chalceus macrolepidotus" in FishBase. December 2021 version.
  14. ^ "Pink-tail Chalceus Species Profile". Maidenhead Aquatics. Retrieved 27 December 2021.
  15. ^ "Yellowfin Chalceus (Chalceus erythrurus)". Aqua-Imports. Retrieved 27 December 2021.
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