Typhlobarbus nudiventris

Chu et Chen 1982.

English Name: Blind naked-belly barbel.

Classification:

Order: Cypriniformes;

Family: Cyprinidae.

Environment: Demersal; freshwater.

Climate: Subtropical.

History: On April 23, 1976, a little fish was found 100 meters deep in underground water in Jianshui County, Yunnan Province when the local people were digging to find a new water source. This specimen was 34 mm in total length, with a semitransparent body, so that the outline of its internal organs could be seen faintly. Its left eye was covered completely by tissue, and its right eye was black and as small as a needlepoint. After careful study, the experts elicited a conclusion: this is blindfish; it was not immediately described scientifically because there was only one specimen. In 1978, the news of „The discovery of the first blind fish from China” issued, confirming their existence*.

Description: D II,8; A II,5; P I,15; V II,8. Body elongated, small and slender, breast and belly flat and gradually compressed rearward; head medium-size. Abdomen rounded. Mouth is inferior and arched; snout rounded and blunt, slightly projected. Gill-membrane broadly joined to isthmus. Gill rakers are triangle-shaped. Lower pharyngeal teeth in two rows. Lips simple and smooth, adnate to maxillar and mandible respectively. Rostral fold covering part of upper lip, not fringed at its edge and not forming a preoral chamber. Rostral groove interrupted at the base of maxillary barbel. Upper lip connected with lower one. Postlabial groove short, only laterally developed and extending to mental groove, which is shallow and inconspicuous. Mental region pad-like, without free rim front nostril opening with a short tube and separated with rear nostril opening by a valve; eye sockets located in center of head, slightly caved-in, filled with adipose or with needle-tip small hole and bottom of hole black, eyeball extremely degenerated. Barbels 2 pairs and lenght of barbels equaled; rostral barbels reach posterior nostrils and maxillary ones extend as far as the vertical from orbit, which is filled by fat globules except a small opening showing the position of extremely regressed eye. Scales medium-sized but naked on center of front back and ventral. No enlarged scales on both sides of anal base. Lateral line complete, normally decurved, running in middle of caudal peduncle; lateral line scales 39-40. The cephalic lateral line appears to be in two series of pores. Dorsal and anal without osseous spine. Five branched anal rays. Last unbranched dorsal fin-ray soft and smooth, with distal margin truncate, orgin of dorsal fin opposite to front of origin of pelvic fin; pectoral and pelvic fins expanded flat and located lower; pectoral, pelvic and anal fins large, caudal fin forked and large. Air-bladder with two divisions not enclosed in leathery membrane or bony capusle. In life color of body semitransparent and faint reddish, grayish dark contents of intestine appeared in center of venter. The branchial region is very reddish due to the blood circulation in that area. Fins transparent but caudal fin grayish and with gray edge. Maximum standard lenght 45,5 mm. Monotypic genera.

Distribution: Asia. The fish is an endemic species of China and is distributed only in the underground karst cave at Yangjieba (ca. 23°39′ N, 102°46′ E) of Jianshui County, Yunnan Province.

Habitat and ecology: The underground water in the karst cave is about 100 m below the surface at an altitude of 1,450 m above sea level. The water moves slightly and surrounding is dark.

Food and feeding: Outer shells of chitinozoa have been found in faeces suggesting that plankton is at least part of their diet.

Reproduction and development: External, non-guarder.

Other behavior: Institute of Zoology, Kunming, Chinese Academy of Science (CAS), obtained two fish ot the species in 1981. These were observed for several days after putting them an earthenware container of water. When still, they often supported their bodies on the outer edge of pectoral and pelvic fins with the tip of the lower lobe of the caudal fin and the head raised upward. When swimming, they opened their nostrils, lift the valve of their noses with their snouts extending forward and their bellies against the wall of the container and they again became still after swimming several rounds. They are very sensitive to vibration but show no response to light.

Status: Rare.