Maximum likelihood (ML) phylogenetic tree of Ooceraea species based on COI + COII sequences, with Syscia augustae as the outgroup. Numbers above branches indicate bootstrap values, and nodes with bootstrap support < 75 have been collapsed. Phylogenetic branch lengths (black) measured as the number of substitutions per site (see scale bar). The focal species Ooceraea hainingensis sp. nov. is highlighted in bold.