Roughback whipray
A rare freshwater stingray with a pearl organ on its back.
The roughback whipray (*Fluvitrygon kittipongi*) is a small freshwater stingray, reaching a maximum width of 29 cm (11 in). It lives over sandy bottoms in Thailand’s Mae Klong and Chao Phraya Rivers. Its oval pectoral fin disc and whip-like tail (which lacks fin folds) resemble those of the white-edge freshwater whipray (*F. signifer*), but it can be told apart by its coloring: the upper side ranges from light gray to dark orange-brown, while the underside is white with a dark band along the edges. A key feature present in all ages is a “pearl organ”—an enlarged dermal denticle—at the center of the back. Every original specimen collected had extensive healed wounds on its fins and tail. The International Union for Conservation of Nature (IUCN) lists this species as Endangered due to heavy habitat damage and fishing pressure within its small range.
**Taxonomy** In 2005, WWF Thailand Senior Freshwater Biologist Chavalit Vidthayanon and Smithsonian Research Associate Tyson Roberts described the roughback whipray in the *Natural History Bulletin of the Siam Society*. They named it after Bangkok aquarium dealer and fish expert Khun Jarutanin Kittipong, who had provided the five original specimens the year before. A female 26 cm (10 in) across was chosen as the type specimen. Based on physical form, *F. kittipongi* appears most closely related to *F. signifer*, which shares its range.
**Distribution and habitat** The five original specimens were all caught in the Mae Klong River in Kanchanaburi Province, Thailand, in freshwater above tidal influence. Additional records come from the Chao Phraya River, and possibly the Penang River in Peninsular Malaysia. The total range is estimated at less than 5,000 km² (1,900 mi²). This bottom-dwelling ray lives in main river channels at depths of 5–20 m (16–66 ft). Unlike *F. signifer*, which prefers muddy bottoms, it seems to favor sandy to silty substrates.
**Description** The disc is thin, oval, and slightly longer than wide, with front edges meeting at a broad angle to the snout tip, which ends in a small, protruding knob (larger than in *F. signifer*). The eyes are small, followed by larger, teardrop-shaped spiracles. A skin curtain between the nostrils has a gently concave or lobed rear edge. The small mouth has 4–5 papillae (nipple-like structures) across its floor.
Quick Facts
- Genus
- Fluvitrygon
- Species
- kittipongi
Facts from the source article.
Lore & Background
The roughback whipray was described in 2005 by WWF Thailand Senior Freshwater Biologist Chavalit Vidthayanon and Smithsonian Research Associate Tyson Roberts in the journal Natural History Bulletin of the Siam Society. They named the ray after Bangkok aquarium fish dealer and fish expert Khun Jarutanin Kittipong, who provided the original five specimens. A female 26 cm (10 in) across was designated as the type specimen. Based on morphology, it appears most closely related to the white-edge freshwater whipray (F. signifer), which shares its range.
The original five specimens were all caught from the Mae Klong River in Kanchanaburi Province, Thailand, in fresh water above the tide. Additional records exist from the Chao Phraya River, and perhaps the Penang River in Peninsular Malaysia. This bottom-dwelling species inhabits main river channels at depths of 5–20 m, favoring sandy to silty substrates, unlike F. signifer which prefers muddy bottoms.
All five original specimens bore extensive, healed wounds to the disc and/or pelvic fins, and had much of their tails bitten off, leaving a remnant only 1.3–1.8 times longer than the disc width. Kittipong proposed these wounds are inflicted by pufferfishes (Monotrete cf. leiurus and M. cf. nigroviridis), though why such wounds are seldom found on F. signifer remains a mystery. Another possibility is that the tail truncation is self-inflicted.
Reader's Guide
The roughback whipray is significant as a rare and recently described freshwater stingray with a very limited range estimated at less than 5,000 km². Its Endangered status, assessed by the IUCN, stems from intensive fishing pressure—incidental capture in demersal tangle nets, fish traps, and on hook-and-line—and extensive habitat degradation from deforestation, dam construction, land development, and water pollution. The species may be sold as food or to the aquarium trade. Its legacy is tied to the mystery of the extensive wounds found on all original specimens, which are seldom seen on related species like F. signifer. The ray's small size, distinctive pearl organ, and dark marginal band on the underside help distinguish it from its close relative. The species was named after a local fish expert, highlighting the role of regional knowledge in its discovery.
Did You Know?
- The roughback whipray grows no more than 29 cm (11 in) across.
- It has a 'pearl organ' (enlarged dermal denticle) at the center of the back present throughout life.
- All five original specimens had extensive wounds to the fins and tail, possibly from pufferfish bites.
- The species was named after Bangkok aquarium fish dealer Khun Jarutanin Kittipong.
More in Reef Sharks and Rays, Part 2 1-24
Spotted an error? Know more?
Reader corrections go straight into our review queue. Suggest an edit · How this site is sourced