Hortle's whipray

habitat degradation, leading the International Union for Conservation of Nature

H. uarnacoides.^[2]

mud flats, in water no deeper than 10 m (33 ft).^[1]

pectoral fin disc of the Hortle's whipray is heart-shaped and slightly longer than wide; the anterior margins are concave and converge on a highly elongated, narrowly triangular snout. The eyes are tiny and spaced wide apart, and immediately followed by large, teardrop-shaped spiracles. There is a broad, roughly rectangular curtain of skin between the nostrils with a finely fringed posterior margin. The mouth is strongly bow-shaped and does not contain papillae (nipple-shaped structures). The small, blunt teeth are set closely with a quincunx pattern, and stained orange to brown in adults. There are 21–25 upper and 24–28 lower tooth rows. The five pairs of gill slits are distinctively S-shaped.^[2]

dermal denticles, composed of larger heart-shaped denticles and smaller variably-shaped interstitial denticles, runs along the dorsal surface of the disc from before the eyes to the tail. Small, sharp denticles are scattered over the snout and concentrated at the tip. The tail past the sting is uniformly covered by denticles. The lateral line network is well-developed both over and beneath the disc. Smaller rays are plain greenish gray above, while larger rays are yellowish brown; the tail is uniformly brown and lighter in front of the sting. The underside is distinctively bright yellow, with a thin dark border around the disc margin and sometimes darker blotches around the nostrils, mouth, and gill slits.^[2] The largest known male is 71 cm (28 in) across, and the largest female 65 cm (26 in) across.^[3]

aplacental viviparous, with the females supplying their developing embryos with histotroph ("uterine milk"); the young are born at under 20 cm (7.9 in) across.^[1]

habitat degradation, from the large-scale destruction of mangroves, intensive mining activity, and river pollution. While the Hortle's whipray remains common within its small range, the International Union for Conservation of Nature (IUCN) believes these factors have led to a population decline, and has assessed it as Near Threatened.^[1]