Sharpsnout stingray

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Sharpsnout stingray
Dasyatis geijskesi SI.jpg
Dasyatis geijskesi SI2.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Superorder: Batoidea
Order: Myliobatiformes
Family: Dasyatidae
Genus: Fontitrygon
Species:
F. geijskesi
Binomial name
Fontitrygon geijskesi
Boeseman, 1948
Dasyatis geijskesi range.png
Synonyms

Dasyatis geijskesi

The sharpsnout stingray or wingfin stingray (Fontitygon 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.

Contents

Taxonomy and phylogeny

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 (Hypanus guttata) is the sister species of the sharpsnout stingray, and that the two form a clade with the pale-edged stingray (Telatrygon zugei), the pearl stingray (Fontitrygon margaritella), the sharpnose stingray (Maculabatis 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]

Distribution and habitat

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]

Description

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 3954% 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 5668 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 12 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]

Biology and ecology

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 13 young every year. Similarly to the Colares stingray (Fontitrygon 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]

Human interactions

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]

Related Research Articles

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<span class="mw-page-title-main">Atlantic stingray</span> Species of cartilaginous fish

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<i>Telatrygon acutirostra</i> Species of cartilaginous fish

The sharpnose stingray is a little-known species of stingray in the family Dasyatidae, found off southern Japan and in the East China Sea. With a rounded pectoral fin disc and a long, projecting snout, T. acutirostra resembles the smaller pale-edged stingray. A number of characteristics differentiate this species from T. zugei, including larger eyes and the absence of a dorsal fin fold on the tail. The International Union for Conservation of Nature (IUCN) has assessed this species as Near Threatened, as its restricted distribution renders it vulnerable to increases in fishing pressure.

The Colares stingray, Fontitrygon colarensis, is a species of stingray in the family Dasyatidae, native to the shallow brackish waters of the Amazon River estuary in northern Brazil. This species inhabits inshore bays during the dry season and moves away from the coast in the rainy season. It is characterized by a rhomboid pectoral fin disk, elongated snout, and a dark band on the lower lip. A fairly large species, males and females attain disk widths of 63 cm (25 in) and 91 cm (36 in) respectively. Females give birth to 1–4 young, possibly annually. Colares stingrays are both targeted and caught as bycatch by Brazilian artisanal and commercial fisheries; these pressures coupled with its small range and slow reproductive rate has led the International Union for Conservation of Nature (IUCN) to list this species as critically endangered.

<span class="mw-page-title-main">Longnose stingray</span> Species of cartilaginous fish

The longnose stingray is a species of stingray in the family Dasyatidae, native to the western Atlantic Ocean from the southern Gulf of Mexico to Brazil. Found in coastal waters no deeper than 36 m (118 ft), this demersal species favors muddy or sandy habitats. The longnose stingray is characterized by its angular, rhomboid pectoral fin disc, moderately projecting snout, and whip-like tail with a dorsal keel and ventral fin fold. It typically grows to 1.25 m (4.1 ft) across and is brownish above and light-colored below.

The groovebelly stingray, referred to as the butter stingray by fishery workers, is a species of stingray in the family Dasyatidae. It is found over sandy or muddy bottoms in shallow coastal waters off southern Brazil, and probably Uruguay and Argentina. The groovebelly stingray can be distinguished by a prominent W-shaped furrow on its underside behind the last pair of gill slits, as well as completely smooth skin in all but the largest individuals. It reaches a maximum known width of 65 cm (26 in). This species is aplacental viviparous, with one observed female gestating two young. The main threat to its population is likely bycatch mortality from shrimp trawlers, although habitat degradation is also a concern.

<span class="mw-page-title-main">Mekong freshwater stingray</span> Species of cartilaginous fish

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The Brazilian large-eyed stingray, Hypanus marianae, is a species of stingray in the family Dasyatidae. Endemic to northeastern Brazil, adults of this species inhabit shallow coral and sandstone reefs while the young are also found near beaches and in estuaries. This stingray measures up to 40 cm (16 in) across and can be identified by its large eyes, equally long fin folds above and below the tail, and distinctive coloration consisting of various dark brown markings on a yellowish-brown background above, and two pairs of dark brown blotches on a white background below. Reproduction is aplacental viviparous, with females giving birth to one young at a time, twice a year, and using sandbanks as nursery areas. The Brazilian large-eyed stingray is collected by artisanal fisheries and for the ornamental fish trade.

<span class="mw-page-title-main">Bluntnose stingray</span> Species of cartilaginous fish

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<span class="mw-page-title-main">Pale-edged stingray</span> Species of cartilaginous fish

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<span class="mw-page-title-main">Broad stingray</span> Species of cartilaginous fish

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<span class="mw-page-title-main">Common stingray</span> Species of cartilaginous fish

The common stingray is a species of stingray in the family Dasyatidae, found in the northeastern Atlantic Ocean and the Mediterranean and Black Seas. It typically inhabits sandy or muddy habitats in coastal waters shallower than 60 m (200 ft), often burying itself in sediment. Usually measuring 45 cm (18 in) across, the common stingray has a diamond-shaped pectoral fin disc slightly wider than long, and a whip-like tail with upper and lower fin folds. It can be identified by its plain coloration and mostly smooth skin, except for a row of tubercles along the midline of the back in the largest individuals.

<span class="mw-page-title-main">Roughtail stingray</span> Species of cartilaginous fish

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<span class="mw-page-title-main">Jenkins' whipray</span> Species of cartilaginous fish

The Jenkins' whipray is a species of stingray in the family Dasyatidae, with a wide distribution in the Indo-Pacific region from South Africa to the Malay Archipelago to northern Australia. This large species grows to 1.5 m (4.9 ft) across and has a broad, diamond-shaped pectoral fin disc and a whip-like tail without fin folds. It has a band of heart-shaped dermal denticles running from between the eyes to the tail on its upper surface, along with a characteristic row of large spear-like thorns along the midline. It is uniform yellowish brown above, becoming grayish on the tail past the stinging spine, and white below; there is apparently a spotted color variant that had previously been described as a different species, the dragon stingray.

<span class="mw-page-title-main">Pitted stingray</span> Species of cartilaginous fish

The pitted stingray is a species of stingray in the family Dasyatidae, endemic to the waters around Japan and the Sea of Japan. It typically found near the coast at depths of 40–60 m (130–200 ft), but may also venture into the open sea. Measuring up to 2 m (6.6 ft) across, the pitted stingray has a diamond-shaped pectoral fin disc with a characteristic W-shaped groove on the underside. The total length including the tail has a record of 2.8 m (9.2 ft). Other identifying characteristics of this species include its dark gray dorsal coloration with small white spots, and the presence of dorsal tubercles in adults. Pitted stingrays are caught as bycatch in coastal fisheries and brought to market. The International Union for Conservation of Nature (IUCN) does not yet have sufficient data to assess this species beyond Data Deficient. This species is now regarded as a population of the Short-tail stingray.

<span class="mw-page-title-main">Pearl stingray</span> Species of cartilaginous fish

The pearl stingray is a little-known species of stingray in the family Dasyatidae, found in shallow coastal waters from Mauritania to Angola, though fossils have been found in Portugal. Growing to 30 cm (12 in) across, this species has a rounded pectoral fin disc with a pointed snout, and a wide band of dermal denticles over the back in adults. It closely resembles and is often confused for the much larger daisy stingray ; both species are characterized by the presence of an enlarged, nacreous denticle in the middle of the back called a "pearl spine". The International Union for Conservation of Nature (IUCN) assesses the pearl stingray's conservation status as Near Threatened, but it is likely that most of the historically reported fishery catches of the daisy stingray were in fact of this species.

<span class="mw-page-title-main">Daisy stingray</span> Species of cartilaginous fish

The daisy stingray, Fontitrygon margarita, is a little-known species of stingray in the family Dasyatidae, found in shallow waters along the coast of West Africa. This species typically grows to 60 cm (24 in) across and has a rounded pectoral fin disc and a wide band of dermal denticles over its back. It is characterized by a greatly enlarged, nacreous denticle in the middle of its back called a "pearl spine"; this feature is shared with the similar but much smaller pearl stingray, which has often been confused with this species. The daisy stingray feeds mainly on crustaceans and exhibits aplacental viviparity, with litters of 1–4 young. Heavily pressured by fisheries and possibly habitat degradation, this once-common species is declining and has been assessed as Vulnerable by the International Union for Conservation of Nature (IUCN).

<span class="mw-page-title-main">Bennett's stingray</span> Species of cartilaginous fish

The Bennett's stingray or frilltailed stingray is a little-known species of stingray in the family Dasyatidae, with a wide but ill-defined distribution in the Indian and Pacific Oceans. This species is characterized by a rhomboid, yellow-brown pectoral fin disc with a fairly long snout, and an extremely long tail with a correspondingly long ventral fin fold. It measures up to 50 cm (20 in) across. It feeds on fish, and is aplacental viviparous. It is likely caught by demersal fisheries.

<i>Fontitrygon</i> Genus of cartilaginous fishes

Fontitrygon is a genus of stingrays in the family Dasyatidae found in coastal tropical Atlantic waters and rivers that drain into the Atlantic. Fontitrygon species were formerly contained within the genus Dasyatis.

References

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  7. Santos, H. & P. Charvet-Almeida (2007). "Description of females of the stingray Dasyatis colarensis Santos, Gomes & Charvet-Almeida, 2004 (Chondrichthyes: Myliobatiformes: Dasyatidae)". Arquivos do Museu Nacional, Rio de Janeiro. 65 (1): 19–25.
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