Triplophysa shannanensis, a New Species of Tibetan Stone Loach (Nemacheilidae) from the Yarlung Tsangpo-Brahmaputra River, Tibet

A new species, Triplophysa shannanensis sp. nov., is described from the Yarlung Tsangpo-Brahmaputra River based on morphological and genetic analyses. The new species is distinguished from its congeners by the following combination of characters: posterior chamber of swim bladder developed, ovoid, directly connects to the anterior chamber; intestine short, zigzag-shaped and with two loops; lower jaw spoon-like, blunt, and covered by lips; snout length shorter than postorbital length; dorsal fin origin anterior to the ventral fin origin, and it closer to caudal fin base than tip of snout; the pelvic origin is just below vertical from the second branched dorsal fin ray, and tips of ventral fin reaching to anus or close to anal fin origin; vertebrae 4 + 36–38; gill rakers 10–11. Molecular phylogenetic analysis indicated that the new species is situated in the most basal of the genus Triplophysa species distributed in the Himalayan region of China. The Kimura's 2-parameter interspecific genetic distance of the cytochrome b gene sequences of the new species differed from 5.6 to 20.3% with other Triplophysa species. Two non-native species, T. dalaica and T. scleroptera, were first found in the the Yarlung Tsangpo River, which would bring the number of Triplophysa in the Tibetan Himalaya of China to eleven species. A checklist of genus Triplophysa in Chinese Himalaya was further provided.