Morphological analyses
In order to explore the morphological variation among the different species and the various habitat types of Percocypris, the morphological analyses included both external morphological measurements and aspects of the skeletal system.
For the external morphological analysis, 38 individuals of Percocypris were measured for 34 morphological variables. These were recorded to the nearest 0.1 mm using digital calipers following the methods of Chu & Cui [5] and Zhao & Zhang [19]. The 34 morphological measurements are shown in Figure 2. Summary statistics for all the morphological characters were calculated with the statistical program SPSS 17.0 (SPSS for Windows, Chicago, IL, USA) for the Principal Component Analysis (PCA) after scaling according to standard length.