Collection sites for Candidiopotamon rathbuni (De Man, 1914) (circles) and Candidiopotamon penglai sp. nov. (squares) in Taiwan, as well as other congeners from the Ryukyus, Japan. Different colors indicate sampling sites of clades. Dotted lines indicate the possible biogeographic boundaries between clades NW, W, SW, S, SE, E1, and E2, corresponding to the color in Fig. 2; as well as species. The red star and blue star indicate the type localities of C. rathbuni and C. penglai sp. nov., respectively. Three forms of male left G1 are shown for clades in C. rathbuni and two forms for clades in C. penglai sp. nov.