Common names
Bullseye Round Stingray, Reef Stingray.
Binomial
Urobatis concentricus.
Synonyms
Urolophus concentricus, Urotrygon concentricus.
Identification
A medium-sized round stingray with a sub-circular disc that is slightly longer than or equal to width; disc width 0.9-1.0 x disc length. Snout obtusely angular. Anterior margins of disc almost straight towards snout tip, apices evenly rounded. Disc completely smooth. Pelvic fins broadly triangular with rounded posterior margins, length slightly exceeding width.
Eyes medium-sized; orbit length 0.32-0.34 x snout length. Mouth weakly arched. Nasal curtain skirt-shaped. Nostrils slit-like.
Tail short and broad based, with lateral skin folds that are most prominent anterior to caudal sting. Tail length 47-48% of total length. Caudal sting short, length slightly shorter than caudal fin, origin posterior to mid tail. Caudal fin relatively long and deep, with a high upper lobe and a slightly indented posterior margin.
Colour
Dorsum beige to greyish-brown with concentric dark rings, thin saddles, and a dark stripe along midline. Eye yellowish-orange. Ventrum and lateral skin-folds on tail uniformly white.
Size
Total length 48cm. Length at birth unknown.
Conservation Status
LEAST CONCERN
The bullseye Round Stingray inhabits sandy inshore habitas where it is bycatch component of shrimp trawl fisheries and in artisanal gillnet fisheries. However, it appears to be able to withstand this level of fishing pressure as the overall popultion is relatively stable.
Habitat
Tropical/subtropical seas. Found on soft substrates in shallow bays, lagoons, and estuaries. From close inshore to 30m.
Distribution
Eastern Pacific. The bullseye round stingray is found from Isla Cedros on the west coast of southern Baja, and throughout the Sea of Cortez, southward to Bahía Huatulco in Oaxaca State.
Reproduction
Aplacental viviparous. Litter size unknown.
Diet
Probably small benthic invertebrates.
Behavior
Poorly known.
Reaction to divers
Skittish. Generally moves away once discovered but sometimes tolerant if approached carefully.
Diving logistics
The bullseye round stingray is commonly encountered while diving and snorkelling over sand or near rocky reefs in the southern Sea of Cortez. During March at Cabo Pulmo in southern Baja, I encountered numerous Bullseye stingrays on every dive at ~50ft. On a previous trip during the summer months, none were present implying that this ray has at least a minor migration, perhaps into slightly deeper water when inshore temperatures increase.
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Similar species
Haller’s Round Stingray Distinguished by longer tail and dorsum with small dense light and dark spots overlying a dark honeycomb pattern.
Spotted/Cortez Round Stingray Distinguished by more subtle or absent concentric rings, eye-sized dark spots, and small brown flecks.