Sharpsnout stingray

Lore & Background

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. 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.

The sharpsnout stingray is one of the less common stingrays within its range, 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. It favors muddy habitats 5–25 m (16–82 ft) deep, with low visibility. 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.

The pectoral fin disc 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. 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. The coloration is a uniform brown above, and white below darkening towards the disc margin.

Reader's Guide

The sharpsnout stingray is notable for its distinctive morphology, including a long projecting snout and elongated, acutely pointed pelvic fins that set it apart from other stingrays. Its biology includes feeding on small burrowing invertebrates such as worms, crustaceans, and molluscs, which it excavates from the substrate and grinds with pavement-like teeth. Reproduction is aplacental viviparous, with females giving birth to 1–3 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. Younger individuals have proportionately longer tails (measuring up to three times the disc width) than adults.

The species is under pressure from both artisanal and commercial fisheries. It is caught by hook-and-line or in nets, used for food by subsistence fishers, but is not favored because its flesh is a dark reddish color. 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 in the future. Because of these threats and its slow reproductive rate, the IUCN has assessed it as Critically Endangered. The sharp, venomous tail spines are potentially hazardous to humans.

Did You Know?

• The sharpsnout stingray was described by Dutch ichthyologist Marinus Boeseman in 1948 based on a juvenile male caught off Suriname.
• Its pelvic fins are over twice as long as wide and taper to an acute tip that sometimes extends past the disc.
• The species is one of the less common stingrays within its range, found from Venezuela to northern Brazil.
• Females give birth to 1–3 pups annually, and younger individuals have proportionately longer tails than adults.