Hortle's whipray
A little-known stingray with a bright yellow underside from southern New Guinea.
The Hortle's whipray (Pateobatis hortlei) is a stingray from the family Dasyatidae that lives in the shallow, brackish estuaries and muddy tidal flats off southern New Guinea. Not much is known about this species. It gets its name from Kent Hortle, a biological consultant who gave scientists the first photographs and fresh specimens of the ray. The species was formally described in 2006 in the journal *Zootaxa*, based on an adult male 71 cm (28 in) across caught in the Minajerwi River estuary. This ray is part of the 'uarnacoides' species complex, which also includes *H. chaophraya*, *H. granulata*, *H. lobistoma*, *H. pastinacoides*, and *H. uarnacoides*.
The ray’s range is limited to southern Papua province, and possibly neighboring Papua New Guinea. It stays in water no deeper than 10 m (33 ft), preferring brackish estuaries and intertidal mud flats.
Its pectoral fin disc is heart-shaped and slightly longer than wide, with concave front edges that meet at a long, narrow, pointed snout. The eyes are tiny and set far apart, with large, teardrop-shaped spiracles right behind them. Between the nostrils is a broad, roughly rectangular flap of skin with a finely fringed rear edge. The mouth is strongly curved like a bow and lacks papillae. The small, blunt teeth are arranged in a quincunx pattern and are stained orange to brown in adults, with 21–25 rows in the upper jaw and 24–28 in the lower. The five pairs of gill slits are distinctively S-shaped. The pelvic fins are short and broad. The tail is very thin, 2.6 to 3.4 times as long as the body, and has no fin folds. One or two stinging tail spines sit on the upper surface about one-third of a disc width from the tail base. A wide band of flattened dermal denticles—including larger heart-shaped ones and smaller, irregularly shaped interstitial ones—runs along the back from in front of the eyes to the tail. Small, sharp denticles are scattered over the snout, concentrated at the tip. The tail past the sting is fully covered with denticles. The lateral line system is well-developed on both the upper and lower surfaces. Smaller rays are plain greenish gray above, while larger ones are yellowish brown; the tail is uniformly brown and lighter in front of the sting.
Quick Facts
- Genus
- Pateobatis
- Species
- hortlei
Facts from the source article.
Lore & Background
The Hortle's whipray was formally described by Peter Last, Mabel Manjaji-Matsumoto, and Patricia Kailola in a 2006 issue of the scientific journal Zootaxa. An adult male 71 cm across, collected from the estuary of the Minajerwi River, was designated as the type specimen. This ray belongs to the 'uarnacoides' species complex, along with H. chaophraya, H. granulata, H. lobistoma, H. pastinacoides, and H. uarnacoides.
The pectoral fin disc is heart-shaped and slightly longer than wide, with a highly elongated, narrowly triangular snout and tiny eyes. The underside is distinctively bright yellow, sometimes with darker markings around the nostrils, mouth, and gill slits. A wide band of dermal denticles runs from before the eyes to the tail, and small sharp denticles are scattered on the snout. The tail is very thin, 2.6–3.4 times as long as the body, and lacks fin folds.
Little is known of its natural history. It is presumed to be a predator of crustaceans, molluscs, and small fishes. Reproduction is aplacental viviparous, with females supplying histotroph to developing embryos; young are born at under 20 cm across.
Reader's Guide
The Hortle's whipray is significant as a little-known species restricted to a small range off southern Papua province, and perhaps also neighboring Papua New Guinea. It inhabits brackish water estuaries and intertidal mud flats in water no deeper than 10 m. The species is threatened by extensive seine fisheries, which take it regularly as bycatch, and by habitat degradation from mangrove destruction, intensive mining activity, and river pollution. The meat, and possibly also the skin and cartilage, is utilized. Although it remains common within its small range, the International Union for Conservation of Nature (IUCN) has assessed it as Near Threatened due to these pressures. Its legacy lies in highlighting the vulnerability of poorly known coastal stingrays to cumulative human impacts, and in the taxonomic contribution of its description to the 'uarnacoides' species complex.
Did You Know?
- The Hortle's whipray was named after Kent Hortle, a biological consultant at the Freeport mine in Indonesian Papua.
- The largest known male is 71 cm across, and the largest female 65 cm across.
- It is threatened by beach seine fisheries, mangrove destruction, mining, and river pollution.
More in Reef Sharks and Rays, Part 3 1-24
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