New pinkish eyeless creature is discovered in an underwater cave in China - and it could solve mysteries about evolution

A pinkish, eyeless creature has been discovered in an underwater cave in China that scientists have claimed could answer mysteries about evolution.

Researchers announced a new species of cave fish that lives deep in the Wujiang River System's underground streams, which is blind with its eyes appearing as black dots under its skin.

However, some of the fish appeared to have weak vision, which the team said  could offer 'exceptional cases for evolutionary studies.'

Now it is a race against time save the new species that is already deemed at risk of extinction due to pollution and invasive species. 

Seven specimens of a brand new species of eyeless cave fish (pictured) - each with a golden stripe on its back - have been discovered swimming in China 's subterranean river systems

Ecologists and conservationists identified their first sample of the new pink cave fish in 2019, but it has taken years more field surveys deep in the Wujiang River System's underground streams (pictured above) to catch enough of the fish to prove that it is a new species

The researchers named their cavefish the 'Guiyang Golden-line Barbel,' or more technically Sinocyclocheilus guiyang, after several closely related golden-line barbel species, as well as the city of Guiyang, which is near the new fish's cave river home.

'The fish diversity in the Yangtze River Basin of Guiyang City, the most urbanized area of Guizhou, has long been underestimated,' the researchers said.

As many as 66 related Sinocyclocheilus fish species have been found living in the Pearl River Basin to the south of Guizhou, but only six species have been found in Guizhou's Yangtze River Basin and its local Wujiang River tributary. 

The fish survey team has suspected that still more undiscovered fish will be found in the Wujiang system's vast river caves.

The geology of this Wujiang River System in central Guizhou Province, is mainly limestone and other carbonate rocks known as 'karst,' which dissolve easily in water creating drainages and sinkholes across this region of south-central China.

'Similar to the Pearl River Basin, the Wujiang River System also exhibits extensive and well-developed karst landforms,' the scientists wrote in their new study, 'which has provided good conditions for the formation of subterranean river systems.'

Some examples of the new fish are perfectly eyeless (A, top left) - but others have small 'highly reduced eyes, partially covered with skin,' (B, top right) the team said. This range of blind and weak-vision in one species offers 'exceptional cases for evolutionary studies,' they note

The 'Guiyang Golden-line Barbel' grows to about 5-inches long, with shorter-than-average 'barbels' — the whisker-like protuberances around a fish's face that cave-fish in particular rely on for navigation and finding food. 

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'Extended barbels in Sinocyclocheilus species is common,' the researchers wrote, 'as the long barbels better detect water flow and aid foraging in subterranean water systems which are marked by permanent darkness and food scarcity.'

Currently, it's still a mystery why this Guiyang cave fish did not evolve with these longer, more useful barbells, or why it is missing a 'horn-like' structure on its head common to its barbel cavefish cousins.

As the team reported in the journal Zoosystematics and Evolution this Tuesday, the new cave fish also has 'degenerated' scales, and a generally shorter snout and shorter fins than other Sinocyclocheilus species.

But the new cavefish does have a brilliant golden marking on its back between its head and its dorsal fin, similar to other, related barbel fish. 

'This species is presently only known from a subterranean stream flowing into the Wujiang River,' according to the scientists, which might suggest a smaller habitat.

The fish survey team suspect that still more undiscovered fish will be found in these vast river caves: 'Similar to the Pearl River Basin, the Wujiang River System also [...] has provided good conditions for the formation of subterranean river systems,' they wrote (species sighting map)

While there are over 200 documented species of 'obligate' (blind) and/or 'troglobiotic' (cave-dwelling) fish worldwide, and they are found on every continent except Antarctica, each individual species comes in limited numbers (above, the new cavefish out in the wild)

While there are over 200 scientifically documented species of 'obligate' (blind) and/or 'troglobiotic' (cave-dwelling) fish worldwide, and they are found on every continent except Antarctica, each individual species comes in limited numbers.

Many including America's own 'Hoosier Cavefish' (Amblyopsis hoosieri) and 'Alabama Cavefish' (Speoplatyrhinus poulsoni) exist only within their own closed-off cave networks, putting them at a higher risk for endangerment or extinction.

The fish survey team that discovered the new species — a collaboration between Huazhong University of Science and Technology, the Chinese Academy of Sciences, and several local wildlife agencies — hopes that further identification will help protect these cave-swimming creatures from human encroachment on their homes.

'The new species is the first described troglobiotic species of genus Sinocyclocheilus in the Wujiang River,' they noted.

'[It] faces a high risk of extinction,' they said, 'underscoring the urgency for habitat protection measures within its limited range.'