A NEW FISH OF SINOCYCLOCHEILUS FROM GUANGXI, CHINA WITH A COMMENT ON ITS SOME BIOLOGICAL ADAPTATION (CYPRINIFORMES:CYPRINIDAE)

Sinocyclocheilus macrophthalmus sp. nov. (Fig.1) Holotype No. 70907, 62?mm TL, 47?mm SL, collected from a cave in Xia'ao, Du'an County(23°55′,108°05′E), Guangxi, China,Nov. 1999. The location belongs to Hongshuihe basin of Pearl River. The type is deposited in Fish Collection Room of Institute of Zoology, Chinese Academy of Sciences, Beijing, China. D. iv 8; P. I 16; V. ii 7; A. iii 5. Vartebrae 39. Depth of body in standard body length 3.4, length of head 3.8, length of caudal peduncle 5.2, depth of caudal peduncle 8.3, distance from front origin of pectoral fin to snout 1.8, distance from rear origin of pectoral fin to base of caudal fin 2.7, distance from origin of ventral fin to origin of anal fin 5.5, length of caudal fin 4.1. Depth of head in length of head 1.9, width of head 1.7, length of snout 4.3,diameter of eye 2.8,width of interorbital space 2.9, width of mouth 3.3. Depth of head in width of head 0.9. Depth of caudal peduncle in length of caudal peduncle 1.6. Body elongate, front trunk columnar and caudal trunk compressd. Head large. Snout conical. Mouth terminal or weak subinferior, length of lower and upper jaws near equal; slit of mouth arced. Lips thin, upper and lower lips connected in corners of mouth, grooves of lower lip reached near chin but inconnected. Eyes very large and superlateral. 4 barbels, long but slender; length of them near equal. Gill membrane connected to isthmus. Origin of dorsal fin located about in middle of body. Origins of ventral fins opposite to second branched dorsal fin ray. Pectoral fin not reached backward origin of ventral fin. Ventral fin not reached backward anal fin. Caudal fin forked. Anus located just before origin of anal fin. Scales fine and observed under stereoscope. Lateral line complete. The specimen just caught from the cave was transparent and viscus could be observed clearly. Breeding in aquarium in lab over five months, the body of the fish became obscure, but the muscle is also somewhat transparent except venter and most vertebrae and brood in tail can be observed easily under the stereoscope. The peritoneum of the fish shows silvery and opaque, so the viscus can not be observed now. All fins are transparent. The new species differs from all other known species in Sinocyclocheilus but is similar to S. macrolepis and S. macroscalus in having no frontlet, scales, complete lateral line and distribution in Hongshuihe basin. But the fish differs from above two species in 1) the proportions of snout length and eye diameter in head length;2) the position of the pectoral and ventral fins is similar to S. macrolepis but different from S. macroscalus ; 3) the serration along the back edge of the last umbranched dorsal fin ray is present in S. macroscalus but absent in S. macrolepis ; 4) the new species is limited to live in cave and 5) the eye of the new species is the largest in the genus.