A review of the Nemacheilinae genus Oreonectes Gunther with descriptions of two new species (Teleostei: Balitoridae)

The loach genus Oreonectes is reviewed in this study. Six valid species are recognized, including two new species. Oreonectes polystigmus sp. nov., and Oreonectes microphthalmus sp. nov. are described from the Guangxi Zhuang Autonomous Region, China. Among its congeners, O. polystigmus is most similar to O. platycephalus in morphology. It can be distinguished from all its congeners by an incomplete lateral line with 6–8 pores; a cephalic lateral-line system with 7 supraorbital and 4+7 infraorbital pores; sexual dimorphism (males have a genital papilla located immediately posterior of the anus, and the gonad is opened at the end of a fleshy prominence); and a body with many differently shaped spots. Oreonectes microphthalmus is most similar to O. furcocaudalis in morphology. It can be distinguished from all congeners by its degenerate eyes, which only have black pigment; a cephalic lateral-line system with 2+2 supratemporal, 7 supraorbital, 3+0 infraorbital and 8 preoperculomandibular pores; and an incomplete lateral line with 3 pores. A key to all valid Oreonectes species is provided. The validity of some related species is discussed. Nemacheilus liboensis, Oreonectes liboensis and Oreonectes translucens are all proved to be synonyms of Paracobitis longibarbatus, and Paracobitis longibarbatus is actually a species of Triplophysa.