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Fontitrygon geijskesi ist eine Stechrochenart und lebt im äquatorialen Westatlantik zwischen den Küsten Venezuelas und des nördlichen Brasilien (Bundesstaat Amapá). Möglicherweise ist die Art auch in der Karibik verbreitet.
Fontitrygon geijskesi hat eine runde Brustflossen-Scheibe, die etwa so breit wie lang ist, und erreicht meist eine Scheibenbreite von 70 cm (Maximum 1,50 Meter). Das spitze Rostrum ragt weit über die Scheibe hinaus und ist etwa halb so lang wie diese. Der peitschenähnliche Schwanz ist mehr als doppelt so lang wie die Scheibe und trägt einen oder zwei Giftstachel. Die Oberseite ist dunkelbraun. Die Unterseite ist weiß, an den Rändern grau. Die Zähne sind gelblich weiß.
Der Rochen lebt küstennah im Flachwasser zwischen 5 und 80 Metern und geht auch in Brackwasser. Einen Nachweis gibt es auch aus einer Tiefe von 810 Metern. Während der äquatorialen Trockenzeiten hält er sich näher, während der Regenzeiten etwas weiter entfernt von der Küste auf. Er ernährt sich von Wirbellosen wie Würmern, Krebstieren und Weichtieren, die er meist aus dem Meeresboden ausgräbt. Die Art ist ovovivipar mit Würfen von ein bis drei Jungtieren. Im Uterus ernähren sich die Embryos zunächst vom Eidotter, dann von einer schleimigen, vom Uterus ausgeschiedenen, schleimigen Flüssigkeit die mit Fett und Proteinen angereichert ist.
Die Rochenart wurde im Jahr 2004 durch den niederländischen Ichthyologen Marinus Boeseman unter der wissenschaftlichen Bezeichnung Dasyatis geijskesi beschrieben. Bei einer Mitte 2016 erfolgten Revision der Dasyatidae wurde die Art in die neu eingeführte Gattung Fontitrygon gestellt.[1]
Fontitrygon geijskesi ist eine Stechrochenart und lebt im äquatorialen Westatlantik zwischen den Küsten Venezuelas und des nördlichen Brasilien (Bundesstaat Amapá). Möglicherweise ist die Art auch in der Karibik verbreitet.
The sharpsnout stingray or wingfin stingray (Dasyatis geijskesi) is a species of stingray in the family Dasyatidae, found from off Venezuela to northern Brazil. It inhabits shallow, brackish water, shifting towards the coast in the dry season and away from it in the rainy season. Typically measuring 70 cm (28 in) across, this dark brown ray is easily identifiable by its long, projecting snout and elongated, acutely pointed pelvic fins. Its diet consists of bottom-dwelling invertebrates. Reproduction is aplacental viviparous, with females bearing one to three pups annually. Naturally uncommon and slow-reproducing, the sharpnose stingray is under pressure by both artisanal and commercial fisheries, leading the International Union for Conservation of Nature (IUCN) to assess it as critically endangered.
Dutch ichthyologist Marinus Boeseman described the sharpsnout stingray in a 1948 issue of the scientific journal Zoologische Mededelingen, based on a juvenile male caught off Suriname with a disc length of 36 cm (14 in). The whereabouts of this type specimen is unknown.[2][3] In a 2001 phylogenetic analysis based on morphological characters, Lisa Rosenberger found that the longnose stingray (D. guttata) is the sister species of the sharpsnout stingray, and that the two form a clade with the pale-edged stingray (D. zugei), the pearl stingray (D. margaritella), the sharpnose stingray (Himantura gerrardi), and the smooth butterfly ray (Gymnura micrura, included in the study as an outgroup). These results support the growing consensus that neither Dasyatis nor Himantura are monophyletic.[4]
One of the less common stingrays within its range, the sharpsnout stingray is found in nearshore, brackish waters along the northeastern coast of South America, from Venezuela and Trinidad and Tobago to northern Brazil; many occur in the estuarine area affected by the freshwater discharge of the Amazon River.[1] It favors muddy habitats 5–25 m (16–82 ft) deep, with low visibility.[5][6] However, Uyeno et al. (1983) gave a depth of 810 m (2,660 ft) for this species. The sharpsnout stingray conducts annual movements that are affected by salinity, entering coastal bays such as Marajó Bay during the rainy season and shifting to offshore waters during the rainy season.[1]
The pectoral fin disc of the sharpsnout stingray is about as wide as long, with strongly concave leading margins and rounded corners. The snout is long and projecting, measuring 39–54% as long as the disc is wide. The eyes are minute and followed by much larger spiracles. There is a flap of skin between the nares, with a finely fringed posterior margin. The line of the mouth is slightly indented at the center. The upper and lower jaws both contain 56–68 tooth rows; the teeth are blunt and arranged with a quincunx pattern. A transverse row of 5 papillae are present on the floor of the mouth.[2][7]
The pelvic fins are distinctive, being over twice as long as wide with a gently sinuous trailing margin, and tapering to an acute tip that sometimes extends past the disc. The whip-like tail measures over twice the length of the disc and bears 1–2 serrated spines on top. Posterior to the spines are a subtle dorsal keel and a ventral fin fold about half as long as the disc. A band of small tubercles runs along the dorsal midline from behind the eyes to the base of the tail (excluding a posterior portion of the disc), with larger tubercles in a central row and on each "shoulder". More conical tubercles are scattered over the upper surface of the tail past the spines. The coloration is a uniform brown above, and white below darkening towards the disc margin.[2] This species typically attains a disc width of 70 cm (28 in), but individuals up to 1.5 m (4.9 ft) across have been recorded.[8]
The sharpsnout stingray feeds on small burrowing invertebrates such as worms, crustaceans, and molluscs, excavating them from the substrate and grinding them apart with its pavement-like teeth.[6] Like other stingrays, this species is aplacental viviparous, with females giving birth to 1–3 young every year. Similarly to the Colares stingray (D. colarensis), the annual movements of this ray may relate to reproduction as most females found near the coast are newly impregnated.[1] Younger individuals have proportionately longer tails (measuring up to three times the disc width) than adults.[6]
The sharp, venomous tail spines of the sharpsnout stingray are potentially hazardous to humans.[6] This species is caught by hook-and-line or in nets; it is used for food by subsistence fishers, but is not favored because its flesh is a dark reddish color.[1] Sharpsnout stingrays also form part of the bycatch of artisanal and commercial fisheries targeting large catfish in the Amazon estuary, while increasing interest in using stingrays for minced fish products may intensify fishing pressure on this species in the future. Because of these threats and the slow reproductive rate of this ray, the International Union for Conservation of Nature (IUCN) has assessed it as Critically Endangered.[1]
The sharpsnout stingray or wingfin stingray (Dasyatis geijskesi) is a species of stingray in the family Dasyatidae, found from off Venezuela to northern Brazil. It inhabits shallow, brackish water, shifting towards the coast in the dry season and away from it in the rainy season. Typically measuring 70 cm (28 in) across, this dark brown ray is easily identifiable by its long, projecting snout and elongated, acutely pointed pelvic fins. Its diet consists of bottom-dwelling invertebrates. Reproduction is aplacental viviparous, with females bearing one to three pups annually. Naturally uncommon and slow-reproducing, the sharpnose stingray is under pressure by both artisanal and commercial fisheries, leading the International Union for Conservation of Nature (IUCN) to assess it as critically endangered.
Fontitrygon geijskesi es una especie de pez de la familia Dasyatidae en el orden de los Rajiformes.
• Los machos pueden llegar alcanzar los 150 cm de longitud total.[2][3]
Es ovíparo.
Es un pez de mar y de clima tropical y demersal que vive entre 5-25 m de profundidad.
Se encuentra en el Océano Atlántico occidental: desde la costa septentrional de Venezuela hasta el Brasil.
Fontitrygon geijskesi es una especie de pez de la familia Dasyatidae en el orden de los Rajiformes.
Dasyatis geijskesi Dasyatis generoko animalia da. Arrainen barruko Dasyatidae familian sailkatzen da.
Dasyatis geijskesi Dasyatis generoko animalia da. Arrainen barruko Dasyatidae familian sailkatzen da.
Dasyatis geijskesi est une espèce de raie appartenant à la famille des Dasyatidés.
