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| Clarias gracilentus | |
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| Species: | C. gracilentus
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Clarias gracilentus is a species of freshwater catfish. It was described from Phu Quoc Island (Vietnam), coast of south eastern Cambodia and mainland south eastern Cambodia. The species is a member of the C. nieuhofii species complex. Its name comes from Greek chlaros, meaning lively; in reference of ability to live for long periods out of water.
The species was first described by H. H. Ng, K. H. Dang and V. T. Nguyen in 2011[1].
The specific epithet is the Latin adjective gracilentus, meaning slender, in reference to the slimmer body comparing to Clarias nieuhofii.
Distribution
[edit]Clarias gracilentus is known from the Rach Tram and Rach Vem drainages on the northern part of Phú Quốc Island, Vietnam, and from the Kampot River drainage in southern Cambodia. This species is expected to occur elsewhere on Phú Quốc and in southern Cambodia, but further surveys are needed to verify this.[citation needed]
Description
[edit]Clarias species are characterized by having an elongated body; a soft rayed dorsal fin extending nearly to the caudal fin base; a soft rayed anal fin extending from just behind the anus to the caudal fin base; pectoral fins each with a serrated anterior bony spine; head depressed, covered largely by firmly sutured, surface sculptured bony plates forming a protective helmet; four pairs of flagellate barbels (nasals, maxillaries, inner and outer mandibulars); air-breathing organs derived from the 2nd and 4th epibranchials within a superbranchial chamber.
The new species is a member of the C.nieuhofii species complex. They can be distinguished from them in combination of : head width 11.9–12.9% SL, distance between the occipital process an d the base of the first dorsal-fin ray 5.3–8.4% SL, pecto- ral-fin length 8.5–10.1% SL, body depth at anus 8.2–11.7% SL, pelvic-fin length 4.3–5.5% SL, length of anal-fin base 60.0–63.9% SL, eye diameter 5.4–7.2% HL, interorbital distance 42.7–48.0% HL, occipital-process length 7.8–14.7% HL, 96–101 dorsal-fin rays, 84–89 anal-fin rays and 80–84 total vertebrae
The genital papilla, which is to the right of the anus as you look at the fish with its head to the left, is elongated and pointed in males while it is round and relatively larger (and larger than the anus) in females. In ventral view especially, females are much broader in the body than males of equal age and rearing practices.
Enviroment
[edit]On Phu Quoc C. gracilentus usually lives in forested mires and slowly flowing waters. In dry season fish hides in small holes under dead trees. Water has 24-27 °C , pH 4.5-5.5 and has good oxygenation(4-1).
In the area of their natural behaviour live other fishes: Monopterus albus (Synbranchidae) and Channasp.(Channidae).You can also recognize freshwater crabs , molluscs and arthropods .
References
[edit]- ^ Hee Ng, Heok; Khanh Hong, Dang; Van Tu, Nguyen (2011). "Clarias gracilentus, a new walking catfish (Teleostei: Clariidae) from Vietnam and Cambodia" (PDF). Zootaxa (2823): 61–68. ISSN 1175-5326.
{{cite journal}}: CS1 maint: postscript (link)
Bibliography
[edit]- [1] WIETNAM:ICHTHYOFAUNASTRUCTUREANDSOMEREMARKSONTHEMAJOR EVOLUTIONARYTRENDSINITSGENESIS EkaterinaD.VASIL’EVA andVictorP.VASIL’EV
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