The last thing you might expect to find in a completely dark cave in China is a unicorn. But for researchers, that is exactly what happened. The new species belongs to the genus Sinocyclocheilus and has a rather unusual appearance – but, of course, the classic unicorn horn.
In southern China, 32 specimens were collected from a cave during a cavefish diversity survey. It turns out that 15 of these specimens represented a totally new species. The new species was carefully compared to known species within the same genus using morphological comparisons and phylogenetic analysis and was given the name Sinocyclocheilus longicornus sp. nov., from the Latin words "longus", meaning long, and "cornu", meaning horn.
This new discovery brings the number of species in that genus to 77, 13 of which are found in the same province – Guizhou – as the new species, and all of which are found in China.
The new species has an unforked horn-like structure on its forehead and small eyes that are degenerated, meaning it can’t see well. However, since it lives in total darkness, it doesn’t need them. Some species in the same genus lack the horn-like structure and these are found to live in more well-lit waters, leading researchers to believe that the horn could be related to the new species’ dark lifestyle.
Cavefish often have unusual morphological characteristics. In Mexico, cavefish are shedding light on human obesity by being particularly rotund. Meanwhile, in Thailand, they have learnt to walk and climb.
The cavefish is between 10.5 to 14.6 centimeters long (4.1 to 5.7 inches) and has a lack of pigmentation in it’s scales, giving it a ghostly whitish appearance. The pool in which it was found measures only 1.8 meters wide (5.9 feet) and less than a meter deep (2.6 feet). The team found that the new species was not closely related to other long horned species in the same genus and suggest that comparing the environmental conditions to these other species may reveal what the horn is used for.
The study is published in ZooKeys.