Sinocyclocheilus longicornus, a fish found in a cave in southwestern China’s Guizhou Province, has a mysterious horn-like structure on the back of its head.

Catfish is a genus of freshwater fish endemic to China. First described in 1936, it includes 76 valid species, 71 of which are grouped into five species groups.

Catfish is a genus of freshwater fish endemic to China.
Most members of the genus live in or around caves, and most have adaptations typical of cavefish, such as lack of fins, lack of pigmentation, and impaired vision. Some species have “horns” on the back of their heads, but what these horns do no one can quite say.

In contrast, species that live on land, and some that are found underground, do not show significant adaptations to cavefish.

Perhaps Sinocyclocheilus has adapted to the cave habitat
Perhaps Sinocyclocheilus has adapted to the cave habitat

There are multiple theories that Sinocyclocheilus adapted cave habitats in response to the aridity of Late Miocene and Paleocene China.
Dr. Zhou Jiang from Guizhou Normal University and his colleagues said: “The genus Aurinosaurus is endemic to my country, mainly distributed in the karst regions of southwest China, including Guangxi, Guizhou, Yunnan, Hubei and other provinces.”

“The narrow distribution, morphological similarities and adaptations to cave environments, such as degeneration or loss of eye and body scales, make the classification of this genus difficult and often controversial. Debate”.

“Almost all Sinocyclocheilus species have differently developed horn-like eyes and structures at the back of the brain,” the scientists said.

“Eye Morphology Including Normal, Microphthalmia, and Ophthalmic Diseases”.

“Normal-eyed and small-eyed species are distributed in eastern Guangxi through southern Guizhou to eastern Yunnan, while aophthalmic species are mainly distributed in the Honghe River Basin in northern Guangxi and the Nanpanjiang River Basin in eastern Yunnan.”

“Angular structures are mainly found in the species Sinocyclocheilus angleis and Sinocyclocheilus microphthalmus”.

“These horned species are distributed in the Nanbanjiang, Beipanjiang and Hongshui river basins in the upper reaches of the Pearl River.”

Strange new fish species with mysterious horn-like structure found on the back of its head 2

Adaptive traits such as eye degeneration and horn evolution were found in cave system-related clades in Guangxi and Guizhou provinces. Studies combining multiple methods of morphology, phylogeny, rate analysis, molecular dating and distribution revealed unique patterns and outliers in the Sinocclocheilus population, making it a valuable model for discovering evolutionary novelties.
The newly described species Sinocyclocheilus longicornus was found in only one location, a vertical cave at an altitude of 2,276 m from Hongguo Town, Guizhou Province, China.

“There was no light inside the cave. Individuals of the species Sinocyclocheilus longicornus were lying in small puddles about 25 meters from the entrance of the cave,” the researchers said.

“The puddle is about 1.8 meters wide and about 80 centimeters deep. The water temperature at the time of sampling was 16 degrees Celsius and the pH of the water was 7.4.”

Sinocyclocheilus longicornus has an albino fish-like body with no scales, no pigment, and small, degenerated eyes. It also has a relatively long, unbranched horn-like structure on the back of its head.

The scientists added: “Sinocyclocheilus longicornus clustered together with eight species of the Sinocyclocheilus angularis group on the phylogenetic tree and can be subdivided into Clade I and Clade II. Angular structures of variable length are present in Clade I and Clade II, respectively. middle. .

“Based on the current study and previous phylogenetic trees, we hypothesize that the evolution of such horns may have occurred in at least two separate forms, a waning event and a loss event”.

“For the eye, this may be related to the reduction in eye size during evolution or the abundance and lack of food during growth and development and related genetic mutations.”

An article in the journal ZooKes reports the discovery of this new fish – Sinocyclocheilus longicornus.

Strange new fish species with mysterious horn-like structure found on the back of the head

By using ƊNA barcoding technology for morphological analysis and comparison, scientists identified it as a new species and named it a new species.