Eyeless river creature with ‘visible’ skull found lurking in cave. It’s a new species
In an underground cave of southern China, an eyeless river creature with an externally “visible” skull moved through the dark waters. Its hard-to-reach home helped it go largely unnoticed.
But when scientists eventually found the lurking animal, it turned out to be a new species.
Researchers ventured into the rocky karst caves of Guangxi Province several times in 2024 to survey subterranean river life, according to a study published Feb. 21 in the peer-reviewed journal ZooKeys. A photo shows one of these shadowy caves.
During their visits, the team found a few “extremely rare” cave fish, the study said. Intrigued, they took a closer look at the animals and quickly realized they’d discovered a new species: Protocobitis longibarba, or the long-barbel cave loach.
Long-barbel cave loaches have “elongate” bodies, reaching over 2 inches in length, the study said. Most of their body is “covered with sparse and minute scales, shallowly embedded in (the) skin surface.” Their “short” heads are “eyeless” with “thin” lips.
A photo shows the pale, slightly pinkish hue of the new species. Its “head and all fins (are) transparent” and the “outline of (its) skull (is) visible through (its) skin.”
Researchers said they named the new species after the Latin words “long” and “barba,” meaning “barbel,” because of the whisker-like features near its mouth.
Long-barbel cave loaches have other physical adaptations, such as “degenerate” ribs and “thick” walls on their chests and abdomen, the study said. They also lack an air bladder, suggesting they might engage in “mud-burrowing activities” where “reduced buoyancy” is helpful.
Researchers found long-barbel cave loaches in one underground river system with “clear and unpolluted” water and another which “acts as a conduit for surface water, domestic waste, and mud.” The fish likely feed on algae and other organic waste, but their environment generally has a “limited food supply.”
“Cavefish populations are extremely rare and highly sensitive to human disturbances due to their specialized habitats,” the study said. “Consequently, establishing effective protection measures is crucial.”
So far, the new species has only been found at two sites in neighboring Lingyun County and Fengshan County of Guangxi Province, a region of southern China bordering Vietnam, the study said.
The new species was identified by its scales, head size, fin shape and other subtle physical features, the study said. DNA found the new species had at least 6% genetic divergence from other related fish species.
The research team included Zhi-Xian Qin, Ye-Wei Liu, Si-Yu Zhang, Jing-Song Shi, Li-Na Du and Jia-Jun Zhou.
This story was originally published February 21, 2025 at 1:18 PM with the headline "Eyeless river creature with ‘visible’ skull found lurking in cave. It’s a new species."
