3.3 | Species delimitation
At present, Sinocyclocheilus grahami is the onlySinocyclocheilus species described from Dianchi Lake (Regan, 1904). This species is distributed in the upper reaches of the Pudu River and in a tributary on the right of the Jinsha River. In addition to the S. grahami , three other Sinocyclocheilus species,S. guanduensis , S. huanglongdongensis and S. heiare known from (Xiao et al., 2004). Based on our examination of type specimens of these three species, it is believed that the DNA sequence results show that they are very different from each other, which is due to the high genetic diversity of S. grahami . As the fourSinocyclocheilus species are not clearly differentiated in morphology, S. guanduensis , S. huanglongdongensis andS. hei are considered to be synonyms of S. grahami (Zhao & Zhang, 2009). The maximum likelihood (ML) tree revealed that theSinocyclocheilus populations from the Chenglong vauclusian spring (C) and the Fuming vauclusian spring (F) in Dianchi Lake are clustered within Sinocyclocheilus tingi . Furthermore, the morphological characteristics of individuals from these populations were clearly distinct from those of S. grahami and the synonymized taxaS. guanduensis , S. huanglongdongensis and S. hei . We therefore propose that individuals from the Chenglong vauclusian spring (C) and Fuming vauclusian spring (F) populations constitute an undescribed Sinocyclocheilus species, which we intend to formally describe at a later stage.
3.4 | Divergence times estimates
Based on the RAD-seq data, we estimated the age of the most recent common ancestor (MRCA) of Sinocyclocheilus in the central Yunnan Basin at approximately 3.75~3.11 Ma. The earliest differentiation event occurred at 2.54~2.15 Ma, between the Mile (YN-ML) and Qujing (YN-QJ) populations. This was followed by the differentiation of the Dianchi and Fuxian lake population (YN-DF) and the Qujing population (YN-QJ) 1.43~1.18 Ma(Fig. 3) . The relatively late tectonic uplift of the Tibetan Plateau 3.6 Ma (Qingzang movement: 3.6~1.7 Ma, Kunhuang movement: 1.1~0.6 Ma) may have affected the population dynamics of Sinocyclocheilus in the central Yunnan Basin.