09-07-2025
‘Modest' creature found in remote stream in Laos. See the ‘humble' new species
In southern Laos, the Dakchung Plateau sticks out from the mountains of the Annamite Range.
The 24-by-37-mile area is drained by the Xe Kaman, a river dotted by hydropower projects. Access to the river is 'limited and dangerous.'
It's also the home of a newly discovered species.
Sewellia pudens, a species of loach, was found by researchers in a flowing tributary of the Xe Kaman in an area with cloudy and rippling water over sediment and stones, according to a study published June 24 in the peer-reviewed journal Raffles Bulletin of Zoology.
The 2-inch-long fish are different from other related species because of their generally boring coloration, researchers said.
'The Latin adjective 'pudens' means modest, humble, reserved, discreet. It refers to the absence of conspicuous pattern on the body and fins (compared to most other species of the genus) and the absence of ostentatious modification on (the rays of the fins),' according to the study.
The fish have an almost stingray-like body with wide fins on the side of their bodies that taper to a skinnier tail, photos show.
The modest loache's body is 'entirely covered by scales, except on belly from throat to base of the last pelvic-fin rays,' researchers said.
Their snouts are rounded, and larger males are covered with 'conspicuous' bumps around their mouths, according to the study.
The bumps are smaller in females, or in some cases non-existent, according to the study.
The fish's downward turned mouth also has pairs of 'fan-shaped' barbels in front of the opening and on the sides, researchers said.
The loaches are generally brown and yellow, with saddle-like blotches along their backs, according to the study.
Sewellia, the genus of loaches that now includes the new species, are found in 'fast to very fast current, rapids (and) waterfalls' in the southern slopes of the Annamite range, encompassing parts of Laos, Vietnam and likely Cambodia, researchers said.
They are specially adapted to this environment, researchers said, as their fins and tubercles create a kind of sucking disk that allows them to hold on to rocks or other hard surfaces in the water.
Loaches include a wide variety of fish, but are typically small and found in freshwater systems. They are typically nocturnal, according to Britannica, and use their barbels to sift through the bottom sediment for worms, insect larvae and other sources of food.
Xe Kaman is in southeastern Laos, near the northern border of Cambodia and the western border of Vietnam.
The study was published by Maurice Kottelat.
