''Chalceus spilogyros'', sometimes misspelled as ''Chalceus spilogyrus'', is a species of freshwater fish in the family

Chalceidae Chalceidae, the tucanfishes, is a family of freshwater fish first described by Henry Weed Fowler in the year 1958. It is a monotypic family, home only to the genus ''incertae sedis'' ''Chalceus''. All members of the family inhabit areas of nort ...

that inhabits northern South America. It is a relatively new member of the genus ''Chalceus'', along with '' C. epakros'' and '' C. guaporensis''.

Description

''Chalceus spilogyros'' bears many visual similarities to other ''Chalceus'' species, including metallic scales and a vividly-colored caudal fin (usually red or pink); the rest of its fins are hyaline. Its scales also bear a reticulate (net-like) pattern, which is often uniform across the whole body. It has a comparatively rounded snout, and lacks the thin lateral stripe of ''C. guaporensis'' and ''C. epakros'', but it bears a small-yet-distinct humeral patch (a patch above each of the pectoral fins) to differentiate it from ''C. macrolepidotus'' and ''C. erythrurus''. Its hyaline fins further separate it from ''C. erythrurus'', whose pelvic fins are bright yellow. ''C. erythrurus'' may bear a

humeral spot Humeral spot (from Latin ''humerus'', pertaining to the shoulder) is a mark or pattern found on several species of fish, typically above the pectoral fin Fins are distinctive anatomical features composed of bony spines or rays protruding fro ...

somewhat similar to that of ''C. spilogyros'', but it is less conspicuous, and also has a notch on the upper side. ''C. spilogyros'' may have a lateral stripe on some occasions (likely relating to the mating cycle), but it is much broader and less distinct than those of ''C. epakros'' and ''C. guaporensis''. ''C. spilogyros'' also has a

fontanel A fontanelle (or fontanel) (colloquially, soft spot) is an anatomical feature of the infant human skull comprising soft membranous gaps ( sutures) between the cranial bones that make up the calvaria of a fetus or an infant. Fontanelles allow f ...

(soft, membranous spot) between the frontal and parietal bones of the head to further differentiate it from ''C. epakros'' and ''C. guaporensis'', which have none.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). The longest documented ''C. spilogyros'' specimen was 22.3 cm SL. This makes it one of the larger species of the genus ''Chalceus'', competing with ''C. erythrurus'' (21.4 cm SL) and outsized only by ''C. macrolepidotus'' (24.5 cm SL). In specimens more than 12 cm in length, the head is more robust in comparison to the body, suggesting that 12 cm may be the point of some kind of maturation.

Etymology

The specific name ''spilogyros'' is Greek in origin. "Spilos" means "spot", and "gyros" means "circle" or "round", in reference to the distinct and un-notched humeral spot. As of 2022, it has no widely accepted common name. The genus name ''Chalceus'' comes from the Greek word "chalkos", which means "copper".

Georges Cuvier Jean Léopold Nicolas Frédéric, Baron Cuvier (; 23 August 1769 – 13 May 1832), known as Georges Cuvier, was a French natural history, naturalist and zoology, zoologist, sometimes referred to as the "founding father of paleontology". Cuvier ...

, who originally described the genus, named it so because he observed that the original specimen's scales were copper-colored ("sometimes golden") when preserved in alcohol. This is an observation replicated by modern researchers.

Taxonomy

''Chalceus spilogyros'' is a modern addition to the genus ''Chalceus'', named by Angela M. Zanata and Mônica Toledo-Piza in 2004. the same redescription of ''Chalceus'' also resulted in the recognition of ''C. spilogyros''' congeners '' C. epakros'' and ''C. guaporensis''. While ''C. epakros'' and ''C. guaporensis'' form a

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

of their own, ''C. spilogyros'' shares a clade with the other two recognized species in the genus - the

pinktail chalceus The pinktail chalceus (''Chalceus macrolepidotus''),U.S. Fish and Wildlife Service. Pinktail Chalceus (Chalceus macrolepidotus) Ecological Risk Screening Summary'. 2018. also called the pinktail characin, is a species of freshwater fish of the fa ...

, ''C. macrolepidotus'', and the tucan fish or yellowfin chalceus, ''C. erythrurus''. ''C. macrolepidotus'' is the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

of the genus.

Habitat

''Chalceus spilogyros'' lives in rivers spanning northern

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

, like the other Chalceus species. It largely inhabits the Trompetas,

Tapajós The Tapajós ( pt, Rio Tapajós ) is a river in Brazil. It runs through the Amazon Rainforest and is a major tributary of the Amazon River. When combined with the Juruena River, the Tapajós is approximately long. It is one of the largest clearw ...

, and

Madeira ) , anthem = ( en, "Anthem of the Autonomous Region of Madeira") , song_type = Regional anthem , image_map=EU-Portugal_with_Madeira_circled.svg , map_alt=Location of Madeira , map_caption=Location of Madeira , subdivision_type=Sovereign st ...

rivers, occurring in the lower drainages of the latter two. This puts it as an inhabitant of inland wetland areas. ''C. guaporensis'' is also known to occur in the Madeira river. As of 2022, ''C. spilogyros'' is considered a species of

least concern A least-concern species is a species that has been categorized by the International Union for Conservation of Nature (IUCN) as evaluated as not being a focus of species conservation because the specific species is still plentiful in the wild. T ...

by the

International Union for the Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natura ...

(IUCN).

Diet and behavior

''Chalceus spilogyros''' diet and behavior have not been the subject of intensive study on their own. Other members of the genus have been observed to largely be insectivores, taking occasional plant material as well. The study of behavior is much the same; the pinktail and yellowfin chalceuses in particular have been observed to be active, fast-moving, and somewhat skittish.

References

{{Taxonbar, from=Q6420960 Chalceidae Fish of South America Freshwater animals of South America Fish described in 2004