Garra jiulongi, a new labeonine species (Cypriniformes: Cyprinidae) from the upper Salween-Nujiang River basin, Yunnan, China, with remarks on the intraspecific variability of snout morphology.

Based on morphological comparisons and molecular evidence, a new species, Garra jiulongi is described from the upper reaches of the Salween-Nujiang River drainage in Baoshan City, Yunnan, China. It is the sixth Garra species known from the Salween-Nujiang River basin and, notably, the first Garra species whose type locality is situated in the Chinese section of the drainage. Garra jiulongisp. nov. is closely allied to G. gravelyi in sharing similar meristic counts, but can be distinguished from it by pulvinus enlarged and its width 53.5-64.2% of disc width, and head broader, its width 68.2-77.8% of head length. It can be further distinguished from all other Salween and Chinese congeners by the following combination of characteristics: proboscis unilobed, 12 circumpeduncular scales, 32-34 lateral-line scales, 3.5 transverse scale rows between dorsal-fin origin and lateral line, 9-10 predorsal scales, two pairs of barbels, and breast scaleless. Furthermore, this study critically assesses the intraspecific variability of snout morphology in Garra. We highlight that key snout structures exhibit significant and synchronised plasticity. Such variability renders simplistic, fixed categorisations unreliable. Consequently, we argue that snout morphology should be integrated with a broader suite of morphological characters and non-morphological evidence to ensure robust taxonomic results.