A New Blind Cave Loach of Paracobitis With Comment on Its Characters Evolution

During February and March 1995,a Slovenian caving expedition led by Andrej Miheve in association with the Institute of Karst Geology from Guilin explored the karst region in Libo County,south of Guizhou,a province in China.During the expedition,3 blind loach specimens were collected by Gregor Aljancic,They have been recognized as a new species of the genus Paracobitis:P.longibarbatus sp.nov.The new species possesses the following characters:adipose keel is present along the dorsal and ventral edge of caudal peduncle,depth of adipose keel less than half of depth of caudal peduncle;nostrils are situated closely together,the anterior nostril formed into a tube with a long nostral barbel.These characters indicate that it belongs to the genus Paracobitis,regardless of the presence of a nostral barbel at the terminal of nostral tube.Similar nostral tube was observed also in P.variegatus longidorsalis Yang et al.The eyes and pigment are disappeared as the result of convergent evolution adapting to the lightless habitat.The same convergent phenomena are prevalent in the cavefishes of Cobitidae and Cyprinidae.This new species is the first blind loach in the genus Paracobitis,representing a specialized lineage of the genus.It is related to epigean P.variegatus longidorsalis which occurs in the same basin,Xijiang Basin.The new species can be easily distinguished from all congeneric species by the following characters:eyes and pigment disappeared,anterior nostril tube-like with a nostral barbel at the terminal;barbels,pectoral and pelvic fins well elongated;posterior margin of caudal fin strongly concave.