Groovebelly stingray
A stingray with a W-shaped belly furrow and smooth skin.
The groovebelly stingray (Dasyatis hypostigma), called the butter stingray by fishers, belongs to the family Dasyatidae. It lives over sandy or muddy seafloors in shallow coastal waters off southern Brazil, and likely also off Uruguay and Argentina. Its most distinctive feature is a prominent W-shaped groove on its belly behind the last gill slits, and its skin is completely smooth except in the very largest individuals. This ray reaches a maximum width of about 65 cm. It reproduces through aplacental viviparity; one observed female was carrying two young. The main threat to this species is being caught as bycatch in shrimp trawls, though habitat loss also poses a risk.
The species was formally described in 2004 by Hugo Santos and Marcelo de Carvalho in *Boletim do Museu Nacional*, under the name *Dasyatis hypostigma*—from the Greek *hypo* ("ventral") and *stigma* ("mark"). The original paper sometimes used the spelling *hipostigma*, but the authors later corrected this under the Principle of the First Reviser. The type specimen is an adult male 76 cm long, trawled off the Brazilian state of Paraná. Before this description, groovebelly stingrays caught off Brazil were mistaken for the bluntnose stingray (*D. say*) or the common stingray (*D. pastinaca*), neither of which actually live in the area.
This ray occurs along southern Brazil from Espírito Santo to Rio Grande do Sul, and probably extends north to Bahia and south to Mar del Plata, Argentina. It inhabits inshore waters 5–40 m deep, though it has been reported as deep as 80 m. It prefers sandy or muddy bottoms and may enter estuaries.
The pectoral fin disk is diamond-shaped, slightly wider than long, with nearly straight front edges and a barely projecting snout. The eyes are large and protruding, followed by wide, angular spiracles. A flap of skin between the nostrils has rounded corners and a fringed rear edge. The mouth is small, with a strongly bow-shaped lower jaw. Tooth rows number 37–46 in the upper jaw and 43–50 in the lower, arranged in a quincunx pattern. Teeth are blunt in juveniles and females, but adult males have slender, sharp central teeth. Adults have 3, 5, or 7 papillae in a row across the mouth floor. The underside has a unique W-shaped furrow behind the fifth gill slits—only one other stingray, the pitted stingray (*D. matsubarai*), shares this trait.
Quick Facts
- Genus
- Dasyatis
- Species
- hypostigma
Facts from the source article.
Lore & Background
Hugo Santos and Marcelo de Carvalho formally described the groovebelly stingray in a 2004 volume of Boletim do Museu Nacional, giving it the name Dasyatis hypostigma, from the Greek hypo ('ventral') and stigma ('mark'). The original publication sometimes used the spelling hipostigma, which was subsequently struck as incorrect by the authors under the Principle of the First Reviser. The type specimen is a 76 cm long adult male trawled from off the Brazilian state of Paraná. Prior to its description, specimens caught off Brazil were misidentified as either the bluntnose stingray (D. say) or the common stingray (D. pastinaca), neither of which occur in the region.
The groovebelly stingray has a diamond-shaped pectoral fin disk slightly wider than long, with large protruding eyes and a whip-like tail up to one and a half times the disk length. It bears 1 (occasionally 2) serrated stinging spines. The skin is completely smooth in most individuals, though the largest known female has tiny denticles atop the disk around the tail base. Its dorsal coloration is yellowish to greenish brown, becoming reddish toward the disk margins, with a white underside and black tail fin folds. The only pregnant female examined contained two embryos 55–56 mm long in an early developmental stage.
Reader's Guide
The groovebelly stingray is significant as one of the most common stingrays caught unintentionally by artisanal and commercial shrimp bottom trawlers, mainly off Rio Grande do Sul, Santa Catarina, Paraná, São Paulo and Rio de Janeiro states. Its population faces a primary threat from bycatch mortality in shrimp trawl fisheries, with habitat degradation from coastal development and water pollution also posing concerns. The species is listed as Endangered. Its historical confusion with other stingrays complicates older biological data, but its distinctive W-shaped ventral furrow and smooth skin now allow reliable identification. The groovebelly stingray's aplacental viviparous reproduction, with embryos sustained by yolk and later histotroph delivered via trophonemata, is typical of stingrays. As a benthic inhabitant of sandy or muddy substrates in shallow coastal waters, it plays a role in the ecosystem of southern Brazil and potentially adjacent areas, though its full ecological impact remains understudied due to past misidentification.
Did You Know?
- The groovebelly stingray is distinguished by a prominent W-shaped furrow on its underside behind the last pair of gill slits.
- Prior to its description, specimens were misidentified as the bluntnose stingray or common stingray, which do not occur in the region.
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