Fluvitrygon oxyrhynchus

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Fluvitrygon oxyrhynchus
Specimen of Fluvitrygon oxyrhynchus in the Shedd Aquarium in Chicago.

Specimen of Fluvitrygon oxyrhynchus in the Shedd Aquarium in Chicago.

Systematics
Subclass : Plate gill (Elasmobranchii)
without rank: Stingray (batoidea)
Order : Myliobatiformes
Family : Stingrays (Dasyatidae)
Genre : Fluvitrygon
Type : Fluvitrygon oxyrhynchus
Scientific name
Fluvitrygon oxyrhynchus
( Sauvage , 1878)

Fluvitrygon oxyrhynchus is a small, little-researched and very rare stingray species that occurs in the freshwater and estuary areas of a few rivers in Cambodia , South Vietnam , Thailand , Sumatra and Borneo .

features

The body disc of Fluvitrygon oxyrhynchus is slightly longer than it is wide (the maximum measured width is 36 cm) the whip-like tail is very long, so that the total length of the animals is a maximum of 126 cm. The muzzle protrudes and forms a triangular tip. The back has a reticulate pattern with more or less pronounced hexagonal or irregular spots and is usually light brown. The drawing is less and less pronounced towards the edge of the pectoral fins. The ventral side is monochrome whitish or light brown. The entire back of the fish is densely covered with small placoid scales, the tips of which are flat and heart-shaped. Larger scales are mainly found in the middle of the back and in the shoulder area, where they are arranged in oval-shaped spots. The 26 to 45 scales in the middle of the back and on the tail are arranged in a row. The tail has a sting, but it can also be missing. At the edge of the pectoral fins, the scales, which have a star-shaped base there, become smaller and smaller. The ventral side is completely smooth. The eyes are small, the injection holes are twice the size of the eyes. The mouth is slightly angular. In the upper jaw, the animals have a total of 40 to 42 rows of teeth, only 6 to 7 of which are functional and the others consist of replacement teeth. In the lower jaw there are 10 or 11 functional rows of teeth from a total of 42 to 46. The teeth in both jaws are arranged in a quincunx pattern.

Systematics

The ray species was first scientifically described in 1878 by the French ichthyologist Henri-Émile Sauvage under the name Trygon oxyrhynchus . The American ichthyologist Samuel Garman synonymized the species with Dasybatus uarnak in 1913 and later authors adopted this decision. Pascal P. Deynat and Yves Fermon were able to determine clear differences between the two species and revalidated the species in 2001, giving it the scientific name Himantura oxyrhyncha . In 2016, the genus Fluvitrygon was introduced for three Southeast Asian freshwater ray species .

supporting documents

  1. ↑ Fluvitrygon oxyrhyncha in the endangered Red List species the IUCN 2016 Posted by: Compagno, Hunting Association, 2005. Retrieved on November 11 of 2019.
  2. ↑ a b c Pascal P. Deynat & Yves Fermon (2001). Resurrection of Himantura oxyrhyncha (Sauvage, 1878) from the synonymy of H. uarnak , a senior synonym of H. krempfi (Chabanaud, 1923) (Myliobatiformes: Dasyatidae) ( PDF ). Cybium. 25 (2): 161-176.
  3. ↑ Kent E. Carpenter & Volker H. Niem: The Living Marine Resources of the Western Central Pacific. Volume 3. Batoid fishes, chimaeras and Bony fishes part 1 (Elopidae to Linophrynidae). Rome, FAO. 1998, ISBN 92-5-104302-7 . Page 1503.
  4. ↑ Kottelat, M. (1984): A review of the species of Indochinese fresh-water fishes described by HE Sauvage. Bulletin du Museum National d'Histoire Naturelle, Série 4: Section A: Zoologie, Biologie et Écologie Animales v. 6 (no. 3)
  5. ↑ Last, PR, Naylor, GJP & Manjaji-Matsumoto, BM (2016): A revised classification of the family Dasyatidae (Chondrichthyes: Myliobatiformes) based on new morphological and molecular insights. Zootaxa , 4139 (3): 345-368. doi: 10.11646 / zootaxa.4139.3.2 , page 360.

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