COI tree. Maximum likelihood tree of the genus Bryobia and four outgroup species of the genus Petrobia for part of the mitochondrial COI region. For each haplotype (branch tip) samples sharing that haplotype are given (see Additional file 1 and 2 for abbreviations and sample details). Clades are colored according to their host plant association (see legend in Figure 3). Clades are followed by their presumed species name. Clades of B. kissophila are coded as A-D. Numbers above the branches indicate the percentage bootstrap values based on 100 replicates, numbers below branches depict Bayesian posterior probabilities (only values larger than 50 (ML) and 0.50 (Bayesian) are indicated). The bar at the bottom indicates a branch length of 10% likelihood distance.