Cobitis xui, a new species of spined loach (Teleostei: Cobitidae) from the Pearl River drainage in southern China.

A new spined loach of the genus Cobitis Linnaeus is described from the Buquan River, located in Guangxi Zhuang Autonomous Region, China. The species differs from other members of Cobitis in China by a combination of morphological characters, none of them unique: body depth 14.3‒18.4% SL; lamina circularis long and knife-shaped; Gambetta zones present on the dorsolateral sides of the body (L1‒L5); 8‒11 large transverse elongated blotches on L5; 9‒12 large transverse elongated blotches on L1; maxillary barbels longer than eye diameter; 4‒5 narrow rows of dark spots on the caudal fin; caudal fin with 14 branched rays; a rectangular spot slightly smaller than eye diameter on the upper side of caudal fin base; and caudal-peduncle depth 79.5‒93.1% its length.

[Fish population structure in the fishway of Changzhou hydro-junction].

The fishway of Changzhou hydro-junction, located in the main stream of Xijiang River, is the biggest fishway in China up to now. Efficiency assessment of the Changzhou fishway is important for fish resource and ecosystem protection of the Pearl River, and can provide basic data for design, construction and management of other fishways in China. A total of 40 fish species in the Changzhou fishway were sampled on 11 occasions from April to June during 2011-2014 by using blocking method. Migratory species such as marbled eel, eel, Fugu ocellatus and the four domestic fish ( black carp, grass carp, silver carp and bighead carp) appeared in the fishway. The dominant species included Pelteobagrus vachelli (29.1%), Spualiobarbus' curriculus (16.8%), Hemiculter leucisculus (14.7%), Pseudolaubuca sinensis (12.0%), Squalidus argentatus (10.8%), Anguilla japonica (7.3%) and Cirrhinus molitorella (2.7%). Species accumulation curve indicated that up to 61 species would be monitored in the fishway with increasing the sampling frequency, indicating its good passage efficiency. Fish diversity in the Changzhou fishway was significantly lower than that in the downstream in Xijiang River, and two dominant species in the downstream of the Changzhou Dam, Megalobrama hoffmanni and Mystus guttatus, were not monitored in the fishway in this study, revealing that attraction efficiency of the fishway was different for different fish species. The canonical correspondence analysis showed that dam water level was the most important factor for the fishway effectiveness, it was necessary to adjust the operation mode of the Changzhou dam to instigate more fish migration by the fishway. According to the present situation of fishery resources of the Pearl River, it was suggested to include four domestic fish, M. hoffmanni, S. curriculus and C. molitorella as target species of the Changzhou fishway, and consider more about ecological characteristics of these species.