Sinocyclocheilus xichouensis, a new species of golden-line fish from the Red River drainage in Yunnan, China (Teleostei: Cypriniformes)

In the present study, a new species of the genus Sinocyclocheilus Fang 1936, Sinocyclocheilus xichouensis, was described from the Ganhaizi tributary of Chouyang River, Red River drainage, located in southeast Yunnan, China. This species has normal eyes and a strong dorsal spine with serrations on the lower 3/5 part. In general, this species is similar in morphology to S. macrophthalmus, S. guishanensis, S. angustiporus, S. lateristritus, S. qiubeiensis, S. grahami, S. qujingensis, S. maculatus and S. purpureus distributed in the Nanpanjiang River, and S. qiubeiensis distributed in the Red River. It is distinguished from S. macrophthalmus by possessing fewer than 9 gill rakers. However, S. xichouensis can be distinguished from S. guishanensis by its interorbital width/SL of 8.1~9.9%, rostral barbels extended to posterior margin of eye and maxillary barbels extended to posterior preopercular. It is distinct from S. lateristritus by dorsal-fin origin opposite of pelvic fin origin, with no a black stripe along the lateral line. It is distinguished from S. grahami by 74~88 lateral-line scales, 20 scale rows above the lateral line, and 16 scale rows below the lateral line. It is distinguished from S. qujingensis by a curved lateral line, 74-88 lateral-line scales, 48 circumpeduncular scales. It can be distinguished from S. yimenensis by the ratio of predorsal length, dorsal-fin base length, preanal length, anal fin length, prepectoral length, caudal-peduncle length and lower jaw length to SL, 47.1%-53.7%, 12.8%-15.8%, 66.0%-71.0%, 13.7%-17.1%, 26.0%-29.5%, 19.3%-24.7%, 4.7%-7.0%, respectively. It is distinguished from S. maculatus and S. purpureus by possession of lateral line and scaled body and distinguished from S. angustiporus and S. qiubeiensis by 35~39 predorsal scales, 6 gill rakers, and interorbital width/SL of 8.1%-9.9%.