The inferred phylogenetic relationships between the five helicid mitogenomes available. Branch supports are given for maximum likelihood analyses based on nucleotide data, amino acid data under homogeneous model, and amino acid data under site-heterogeneous model (in this order). The latter was run under alternative settings, see details in the text. Shimodaira–Hasegawa-like approximate likelihood ratio test (SH-aLRT) and standard bootstrap percentages (BP) are reported. Values of SH-aLRT >90 % and BP >75 % are considered positive support. Cylindrus is included as an outgroup.